Preliminary Requirements

Safety Requirements

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURER'S MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS. THESE CONTAIN INFORMATION SUCH AS, HAZARDOUS INGREDIENTS, PHYSICAL/CHEMICAL CHARACTERISTICS, FIRE, EXPLOSION, REACTIVITY, HEALTH HAZARD DATA, PRECAUTIONS FOR SAFE HANDLING, USE AND CONTROL MEASURES AND ALSO TO TAKE LOCAL REGULATIONS INTO CONSIDERATION.

Procedure

1. SUBTASK 70-31-13-310-001 The Definition of Fusion Welding

   1. The fusion welding procedure used in the repair of the engine parts is the fusion of metals to attach the adjacent areas of the parts. This can be done with or without filler metal and without the use of pressure. Also included in fusion welding is 'surfacing'. This is when more material is fused on the surface to 'build-up' or 'hard surface' the base metal.

   2. There are two classes of welds, as follows:

      1. Class 1 - high stress welds.

      2. Class 2 - moderate stress welds.

2. SUBTASK 70-31-13-310-002 Weld Preparation Data, .

   1. Refer to: Figure

   2. Prepare the joint (prepared groove welds).

      Prepare the material joint root face, bevel angle, radius and depth of penetration for the prepared groove welds and plug or slot welds. Refer to Figure.

   3. Make sure the root opening is made as small as possible. It must not be more than the value given, as follows:

      Weld type/Maximum root opening.

      Groove (Arc and Gas processes) /0.060in. (1.52 mm).

      Groove (Electron beam process) /0.003in. (0.08 mm).

      Arc spot and Arc-seam (All processes) /0.000in. (0.00 mm).

      Fillet/0.100in. T(0.254 mm T)*.

      *Maximum sheet separation as determined by the thickness of the thinner sheet (T).

3. SUBTASK 70-31-13-310-003 Material Group Definition

   1. Refer to: Figure

   2. IAE will specify the type of material to be welded. This is shown with the IAE specification number, then a dash and a suffix number, this identifies the material group, as follows:

      Weldment Material Suffix (Group)	Material Type
      -1	Carbon and low alloy steels
      -2	Corrosion resistant, non-precipitation hardenable steels
      -3	Nickel and non-precipitation hardenable nickel alloys
      -4	Aluminum alloys
      -5	Magnesium alloys (not used)
      -6	Commercially pure titanium
      -7	Cobalt alloys
      -8	Copper and copper alloys
      -9	Refractory metals, refractory alloys (columbium, tantalum, tungsten, molybdenum and associated alloys) and oxide dispersion strengthened metals
      -11	Maraging steels
      -22	Corrosion resistant, precipitation hardenable steels
      -33	Precipitation hardenable nickel alloys
      -66	Titanium alloys

   3. When a Repair includes material from two weldment groups, the suffix number has two or more numbers (these are the applicable group numbers). The lower number is shown before the higher, as in the IAE 16 material code examples, as follows:

      Materials to be Welded	Weld Code
      Group 1 to Group 1	IAE 16-1
      Group 1 to Group 11	IAE 16-111
      Group 2 to Group 2	IAE 16-2
      Group 2 to Group 3	IAE 16-23
      Group 2 to Group 22	IAE 16-222
      Group 2 to Group 33	IAE 16-233
      Group 3 to Group 7	IAE 16-37
      Group 3 to Group 22	IAE 16-322
      Group 7 to Group 33	IAE 16-733
      Group 66 to Group 66	IAE 16-66

   4. If the letters HF follow the applicable suffix number for the base metal, it shows the base metal has a hard facing.

   5. For the given filler metal tables, refer to the material groups. This will help during the selection of the correct filler metal. Each suffix group has the specific metal types in it, for example, material Groups 2 and 22, Groups 3 and 33, Groups 7 and 9. Refer to Step for the necessary data for the selection of the filler metal.

   6. The symbol "X" after suffix 66 specifies a special alloy filler is necessary.

4. SUBTASK 70-31-13-310-004 Process Definition

   1. If a letter is added to the tail of the welding symbol (on the Repair illustration), it identifies that a particular weld process is to be used. Optional processes are shown with two or more letters. Refer to Fusion Weld Process letter designations below.

   2. If no reference is made to a particular process (and no letter given in the tail symbol) when you weld the materials below, do as follows:

      For titanium, titanium alloy, refractory metal or refractory alloy joints, weld with the manual or machine gas tungsten-arc, electron beam or plasma-arc process.

   3. Fusion weld process letter designations.

      IAE 16 letter/Fusion weld process/AWS letter:

      A/Manual gas tungsten arc /GTAW-MA.

      J/Machine gas tungsten arc /GTAW-ME.

      K/Manual gas metal arc /GMAW-MA.

      L/Machine gas metal arc /GMAW-ME.

      M/Electron beam/EBW.

      N/Machine plasma-arc (Transferred-arc)/PAW-ME.

      P/Manual plasma-arc (Transferred-arc)/PAW-MA.

   4. Weld symbols.

      NOTE

      AWS publications, AWS A2.4 Symbols for Welding and Nondestructive Testing and AWS A3.0 Welding Terms and Definitions, are available from:

      1. Weld symbols agree with those specified by the American Welding Society (AWS) publication A2.4, except as follows.

         American Welding Society 550 NW LeJeune Road P.O. BOX 351040 Miami, FL 33135-7040 USA Tel: 1-305-443-9353 Fax: 1-305-443-7559

         1. The melt-through symbol will not be used; melt-through is to be controlled by penetration and tolerance requirements specified herein.

         2. When the back or backing weld symbol is shown without the groove weld symbol, it is a flange weld. Size of weld will be as specified.

         3. The location of individual arc spot welds can be shown by centerlines or by the graphic symbol.

         4. For bevel, U, V and J groove welds, where incomplete penetration is permitted, the minimum acceptable penetration can be specified as the sum of two dimensions located to the left of the weld symbol. The first dimension specifies the minimum depth of weld preparation, and the sum of the two dimensions specifies the total minimum depth of penetration.

   5. Weld size.

      1. Weld sizes shown in the repair illustrations will be the minimum requirements for fillet welds, arc spot, arc seam, and groove and flange welds that do not need full penetration, and for plug and slot welds not fully filled.

      2. The size of the plug or slot weld used for joining must be measured from the joint interface.

   6. Finish definition.

      1. The letter "F" specifies that a mechanically smoothed finish is necessary.

      2. To specify a maximum roughness of the finished weld, a standard surface finish symbol with roughness number, lay, and/or waviness designation can be put in the location of the weld finish symbol.

      3. For more information on finishing, refer to Step.

5. SUBTASK 70-31-13-310-005 Filler Metal Data

   
   CAUTION
   THE NECESSARY WELD FILLER WIRE DATA GIVEN DOES NOT PERMIT ITS USE FOR A REPAIR WITHOUT CORRECT APPROVAL OF THE PROCESS TO BE USED.
   YOU MUST NOT USE FLUX WHEN YOU WELD TITANIUM, TITANIUM ALLOYS, REFRACTORY METALS AND REFRACTORY ALLOYS. YOU CAN USE FLUX WHEN YOU WELD OTHER METALS AND METAL ALLOYS BY ALL PROCESSES BUT THESE DO NOT INCLUDE ELECTRON BEAM, LASER BEAM, PLASMA-ARC, GAS TUNGSTEN-ARC, GAS METAL-ARC AND INERTIA-FRICTION PROCEDURES.
   THE FLUX USED MUST NOT BE HARMFUL TO THE COMPOSITION OR PHYSICAL PROPERTIES OF THE WELDED JOINT.

   1. General.

      1. The Repair TASK or the applicable SPM TASK will usually give the weld filler wire necessary for a weld repair.

      2. It is possible that field weld repairs to parts are approved before the Repair is given in the Engine Manual. The selection of the filler metal can be made with reference to this procedure.

      3. The weld filler metal data is only given as general data. You must not use this data as an alternative to the specified instructions given for the applicable parts.

      4. When you make a selection of filler metal, make sure the part (weld member) material is correctly identified.

      5. Unless it is specified in Repair text and/or illustration, you must use filler metal in all weld repairs. Although, these do not include the procedures which follow:

         1. Filler metal is not necessary when you make flange welds where full penetration is necessary.

         2. It is not always necessary to use filler metal when you weld with the electron beam procedure. If filler metal is used, it must be as specified in Step. The filler metal is attached to the joint with resistance-tack or fusion-tack welds before the electron beam weld is made.

   2. The necessary filler metal data.

      1. If filler metal is necessary, as given in Step, you must refer to Step thru 027.

         Welding Filler Metal for Carbon and Low Alloy Steels (Group 1) and Maraging Steels (Group 11)		Step
         Welding filler metal for corrosion resistant steels - non-precipitation hardenable (Group 2) and precipitation hardenable (Group 22)		Step
         Welding Filler Metal for Nickel and Non-precipitation Hardenable Nickel Alloys (Group 3) and Precipitation Hardenable Nickel Alloys (Group 33)		Step
         Welding Filler Metal for Aluminium Alloys (Group 4)		Step
         Welding Filler Metal for Commercially Pure Titanium (Group 6) and Titanium alloys (Group 66) and (Group 66X)		Step
         Welding Filler Metal for Cobalt Alloys (Group 7)		Step
         Welding Filler Metal for Refractory Metals and Refractory Alloys and Oxide Dispersion - Strengthened Metals (Group 9)		Step

         This use of the filler metal does not include the procedures which follow:

         1. The filler metal for welding copper and copper alloys (Group 8) and for other alloys not given, must be as specified in the applicable Repair.

         2. When different alloys are to be welded, the filler metal used must be as specified for one of the two alloys. This is not applicable if there is a specified metal given in Step thru 027 or the Repair.

         3. Loose strips of base metal can be used as an alternative to the specified filler metal. This is not applicable if there is a specified metal given in Step thru 027 or the Repair.

         4. Excess metal given at the edge of a joint or groove can be used as filler metal for lap joint fillet welds and square groove welds.

      2. Carbon and low alloy steels (Group 1) and maraging steels (Group 11). The filler metal must be as given in Step.

      3. Corrosion resistant steels - non-precipitation hardenable (Group 2) and precipitation hardenable (Group 22). The filler metal must be as given in Step.

      4. Nickel and non-precipitation hardenable nickel alloys (Group 3) and precipitation hardenable nickel alloys (Group 33). The filler metal must be as given in Step.

      5. Aluminum alloys (Group 4). The filler metal must be as given in Step.

      6. Commercially pure titanium (Group 6) and titanium alloys (Group 66 and Group 66X). The filler metal must be given in Step.

      7. Cobalt alloys (Group 7). The filler metal must be as given in Step.

      8. Refractory metals and refractory alloys and oxide dispersion-strengthened metals (Group 9). The filler metal must be as given in SUBTASK 70-31-310-027.

6. SUBTASK 70-31-13-310-021 Welding Filler Metal for Carbon and Low Alloy Steels (Group 1) and Maraging Steels (Group 11)

   	PARENT METAL		FILLER METAL NECESSARY
   CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
   1.1	5040 5042 5050 5053 5060 5062 5069 5070 5075 5080 5082	1006 thru 1035	03-133 03-385	AWS70S-2 502 bare
   1.2	5335 5336 6280 6281 6355*	8630	03-385	502 bare
   1.3	6350 6360 6370 6371 6373	4130	03-385	502 bare
   1.4	6437 6485 6487 6488	H-11	03-383	6130
   1.5	6265	9310	03-385	502 bare
   11.1	6512 6520	250 Maraging	03-386	250 Maraging
   11.2	6514 6521	300 Maraging	03-384	300 Maraging
   Notes for Material Group 1 and Group 11:
   * Superseded by AMS 6350. Refer to Category No. 1.3.
   (1) This is general data only. The filler metal must be as in the given specifications.
   (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.

7. SUBTASK 70-31-13-310-022 Welding Filler Metal for Corrosion Resistant Steels - Non-Precipitation Hardenable (Group 2) and Precipitation Hardenable (Group 22)

   	PARENT METAL		FILLER METAL NECESSARY
   CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
   2.1	5350 5351 5504 5591 5613	410	03-392 (3)(7)	410
   2.2	5354 5508 5616 (1464)	Greek Ascoloy	03-378 (3)(7)	Greek Ascoloy
   2.3	5503 5627	430	03-286 (3)	347
   2.4	5548 5554 5745	AM-350	03-371 (3)	AM-350
   2.5	5547 5743	AM-355	03-372 (3)	AM-355
   2.6	5510 5557 5559 5570 5576 5645	321	03-286 (3)(7) 03-463 (3)(7)	347 321
   2.7	5362 5363 5512 5556 5558 5571 5575 5646 5654 (767) (770)	347	03-286 (3)(7)	347
   2.8	5360 5361 5524 5573 5648	316	03-369 (3)(7)	316
   2.9	5365 5366 5521 5572 5577 5651	310	03-370 (7)	310
   2.10	(798) (1079)	AM-363	03-109	AM-363
   2.11	(1091) (1478) (36170)	H-46	03-181	M190
   22.1	5525 5731 5858 5895	A-286	03-209 (6) 03-376	Hastelloy W A286 (Premium)
   22.2	5528 5529 5568	17-7PH	03-286 (5) 03-380 (4)	347 17-7PH
   22.3	5342 5343 5344 5355 5398 5604 5622 5643	17-4PH	03-381 03-375	17-4PH 17-4PH
   22.4	5357 5659 5862	15-5PH	03-381	17-4PH
   Notes for Material Group 2 and Group 22:
   (1) This is general data only. The filler metal must be as in the given specifications.
   (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.
   (3) CoMat 03-209 WELDING FILLER WIRE, NiBASE 5% Cr can be used to weld category 2.1 thru 2.8 to category 3.1 and 3.2.
   (4) Must be used where no other catagory is included.
   (5) Must be used for welding this category to other categories.
   (6) Must be used for all welding of this category, unless specified differently.
   (7) CoMat 03-209 WELDING FILLER WIRE, NiBASE 5% Cr or CoMat 03-287 WELDING FILLER WIRE can be used for welding categories 2.1 or 2.2 to categories 2.6, 2.7, 2.8, or 2.9.

8. SUBTASK 70-31-13-310-023 Welding Filler Metal for Nickel and Non-precipitation Hardenable Nickel Alloys (Group 3) and Precipitation Hardenable Nickel Alloys (Group 33)

   	PARENT METAL		FILLER METAL NECESSARY
   CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
   3.1	5540 5580 5665 (661) (1060)* (1062)** (1070)*	Inconel 600	03-245 (3)(5)	Inconel 62
   3.2	(673)	Nimonic 75	03-203 (3) 03-245 (3)(5)	Nichrome V Inconel 62
   3.3	5390 5536 5587 5588 5754 (1038)	Hastelloy X	03-197	Hastelloy X
   3.4	5388 5389 5530	Hastelloy C	03-367	Hastelloy C
   3.5	5553 (6000) (6005) (6015)	Nickel 200	03-111	Nickels 200
   3.6	5607 5771	Hastelloy N	03-209 (4)(7)	Hastelloy W
   3.7	5401 5581*** 5599 5666 (1468) 5879 (1069) (1072)	Inconel 625	03-287 (6)	Inconel 625
   3.8	5887 5889 (1128) (1165)	Inconel 617	03-390	Inconel 617
   3.9	5711 5873	Hastelloy S	03-382	Hastelloy S
   3.10	5878 (1163) (1127)	Haynes 230	03-464	Haynes 230
   33.1	5660 5661 (1003)	Incoloy 901	03-209 (4)(7)	Hastelloy W
   33.2	5542 5582 5598 5667 5670 5671	Inconel X-750	03-199 (8)	Inconel 69
   33.3	5544 5586 5706 (625) (1471)	Waspaloy	03-244 03-389	Waspaloy
   33.4	5383 5589 5596 5662 (649) (1009) (1065) (1469) (1477)	Inconel 718	03-284	Inconel 718
   33.5	5391 (655)	Inconel 713	03-245 (5)(6)(9) 03-287 (6)	Inconel 62 Inconel 625
   33.6	5606 5702 5703 (1025) (1026)	Inconel 706	03-284	Inconel 718
   33.7	(659)	MAR M 002	03-287 (6)	Inconel 625
   33.8	(1422) (1426)	MAR M 200 +Hf	03-287 (6)	Inconel 625
   33.9	(663) (1445)	B1900 B1900 +Hf	03-287 (6)	Inconel 625
   33.10	(1451)	IN-738	03-287 (6)	Inconel 625
   33.11	(1456) (1467)	IN-792	03-287 (6)	Inconel 625
   33.12	(1447)	MAR M-247	03-287 (6)	Inconel 625
   33.13	(1480) (1484)	454	03-287 (6)	Inconel 625
   33.14	5872	C-263	03-387	C-263
   33.15	(1198)	Haynes 242	03-209	Hastelloy W
   Notes for Material Group 3 and Group 33:
   * Superseded by AMS 5580.
   ** Superseded by AMS 5581, Type 1.
   *** AMS 5581, Type 1 is for tubing with diameters less than 1.00 inch (25.4 mm). AMS 5581, Type 2 is for tubing with diameters 1.00 inch (25.4 mm) or greater.
   (1) This is general data only. The filler metal must be as in the given specifications.
   (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.
   (3) CoMat 03-209 WELDING FILLER WIRE, NiBASE 5% Cr can be used to weld category 2.1 thru 2.8 to category 3.1 and 3.2.
   (4) Must be used for all welding of this category, unless specified differently.
   (5) Must be used for welding by gas metal-arc (GMAW-MA and GMAW-ME), gas tungsten-arc (GTAW-MA and GTAW-ME), plasma-arc, electron beam or laser beam process only.
   (6) Must not be used for welding the airfoils of blades and vanes.
   (7) You must not use parent metal (from all the types available) as filler metal.
   (8) CoMat 03-284 WELDING FILLER WIRE, NiBASE can be used as an alternative to CoMat 03-199 WELDING FILLER WIRE.
   (9) This filler must not be used on parts that will be coated with IAE 73 or other diffused aluminide coatings.

9. SUBTASK 70-31-13-310-024 Welding Filler Metal for Aluminium Alloys (Group 4)

   	PARENT METAL		FILLER METAL NECESSARY
   CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
   4.1	4031 4143 4313	2219	03-393	2319
   4.2	4225	203.OP	03-393	2319
   4.3	All alloys which are welded; this does not include those above.		03-206	4043
   Notes for Material Group 4:
   (1) This is general data only. The filler metal must be as in the given specifications.
   (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.

10. SUBTASK 70-31-13-310-025 Welding Filler Metal for Commercially Pure Titanium (Group 6) and Titanium alloys (Group 66) and (Group 66X)

    	PARENT METAL		FILLER METAL NECESSARY
    CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
    6.1	4900 4901 4902 4921 4941 4942	Comm. Pure Ti	03-214	Comm. Pure Ti
    66.1	4943 4944	3Al-2.5V	03-214	Comm. Pure Ti
    66.2	4909 4910 4924 4926 4966	5Al-2.5Sn	03-483 (3)	5Al-2.5Sn
    66.3	4915 4916 4972 4973 (1202) (1217-2)	8Al-1Mo-1V	03-365	8Al-1Mo-1V
    66.4	4919 4975 4976 (1209) (1214) (1223) (1224) (1225) (1231) (1265) (1267)	6Al-2Sn- 4Zr-2Mo	03-348	6Al-2Sn- 4Zr-2Mo
    66.5	4911 4928 4935 (1217-1) (1232) (1264)	6Al-4V	03-214 03-364 (4) 03-366 (4)	Comm.Pure Ti 6Al-4V 6Al-4V (ELI)
    66.6	4914	15V-3Cr- 3Sn-3Al	03-391	15V-3Cr- 3Sn-3Al
    66.7	(1272) (1274) (1276)	35V-15Cr (Alloy C)	03-394	35V-15Cr (Alloy C)
    66X.1	4911 4928 4935 (1217-1) (1232) (1262) (1264)	6Al-4V	03-195 03-364 (4) 03-366 (4)	6Al-4V 6Al-4V 6Al-4V (ELI)
    66X.2	4943 (1260)	3Al-2.5V	03-195 03-364 (4) 03-366 (4)	6Al-4V 6Al-4V 6Al-4V (ELI)
    Notes for Material Group 6 and Group 66:
    (1) This is general data only. The filler metal must be as in the given specifications.
    (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.
    (3) CoMat 03-214 WELDING FILLER WIRE, TiC.G. PURE can be used as an alternative to CoMat 03-483 WIRE - WELDING, TITANIUMALLOY.
    (4) When a repair specifies CoMat 03-364 WELDING FILLER WIRE, it is always permitted to use CoMat 03-366 WELDING FILLER WIRE, which is a better grade of titanium weld wire. But it is not permitted to use CoMat 03-364 WELDING FILLER WIRE when CoMat 03-366 WELDING FILLER WIRE is specified.

11. SUBTASK 70-31-13-310-026 Welding Filler Metal for Cobalt Alloys (Group 7)

    	PARENT METAL		FILLER METAL NECESSARY
    CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
    7.1	5382	Stellite 31 (X-40)	03-186 03-187	Stellite 31 (X-40)
    7.2	(653)	WI-52	03-243 (3)	Haynes 188
    7.3	5537 5759 (1064)	Haynes 25 (L-605)	03-243 (3)	Haynes 188
    7.4	(657)	MAR M-302	03-243 (3)	Haynes 188
    7.5	5608 5772 (1042) (1088)	Haynes 188	03-243 (3)	Haynes 188
    7.6	(647)	MAR M-509	03-243 (3)	Haynes 188
    Notes for Material Group 7:
    (1) This is general data only. The filler metal must be as in the given specifications.
    (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.
    (3) Any parts that had used CoMat 03-185 WELDING FILLER WIRE (L-605) before June 15, 1993 can continue, but the use of CoMat 03-243 WELDING FILLER WIRE is recommended.

12. SUBTASK 70-31-13-310-027 Welding Filler Metal for Refractory Metals and Refractory Alloys and Oxide Dispersion - Strengthened Metals (Group 9)

    	PARENT METAL		FILLER METAL NECESSARY
    CATEGORY No. (2)	SPEC. AMS (IAE)	TRADE NAME OR TYPE	CoMat NUMBER (NOTES)	TRADE NAME OR TYPE (1)
    9.1	5865 5890	DS Nickel	03-203 (3) 03-368 (3) 03-197 (5) 03-244 (4) 03-389 (4) 03-287 (3) 03-192	Nichrome V Nichrome V Hastelloy X Waspalloy Waspalloy Inconel 625 Waspalloy
    9.2	(1095)	C-103	03-395	C-103
    Notes for Material Group 9:
    (1) This is general data only. The filler metal must be as in the given specifications.
    (2) The category number has the material group number, refer to Step. This number is followed by a decimal number, to make it easier to add subsequent notes.
    (3) Must be used where no other category is included.
    (4) Must be used for welding category 9.1 to category 2.6, 2.7 and 7.1.
    (5) Must be used for welding category 9.1 to 3.3.

13. SUBTASK 70-31-13-310-017 Shielding Gas

    1. The shielding gas must meet the conditions specified in Step as delivered. Monitors are an important aid and must be available to measure the shielding gas oxygen and moisture content.

    2. The shielding gas must flow at a rate that will prevent oxidation of the joint during welding by the processes that follow:

       1. Gas metal-arc.

       2. Gas tungsten-arc, or.

       3. Plasma-arc.

    3. In welding titanium or titanium alloys, and refractory metals or refractory alloys, the shielding gas must fully surround the area to be welded.

14. SUBTASK 70-31-13-310-006 Fusion/Penetration Data

    1. Groove and flange welds must have the penetration completed through the joint and to the point of tangency in flange-groove welds. Refer to Figure and step G.

    2. Fillet welds must have fusion of the component parts at the root of the joint and along each leg of the weld. There is no limit to the depth of penetration. Although, the weld metal build-up must be kept at a minimum on a base metal surface opposite the weld deposit side.

       EXCEPTIONS.

       For aluminum and for other alloys when the included angle between the pieces joined is less than 80 degrees, the fusion of the component parts at the root of the joint is not necessary.

       For aluminum alloys, the maximum dimension of any unfused area, measured from the root, must not be more than 20 percent of the actual weld throat.

       For titanium and titanium alloys, the fusion of the component parts at the root of the joint is not necessary for fillet welds that are less than 0.5 inch (12.7 mm) in length.

    3. Surface welds must show fusion at the interface.

    4. Back or backing welds must have fusion at the root of the joint.

    5. Plug and slot welds must have fusion at all interfaces. There must be a completed depth of filler metal.

    6. Arc-spot and arc-seam welds must have fusion of the component parts at the root of the joint. The penetration depth of arc-spot or arc-seam welds (when specified) must be measured from the root of the joint at the last interface which is welded.

    7. Numbers in parentheses in Figure.

       1. Back or backing weld symbols are always used together with other weld symbols.

       2. The illustrated weld symbols only show the fusion weld (arc-spot and arc-seam) nuggets. The spot or projection weld symbols and seam weld symbols are used to show fusion or resistance welds.

       3. The symbol for a flash or upset weld is the same as the symbol for a square groove weld made from both sides. A weld process code letter added in the welding symbol tail shows which process is to be used to make the weld.

15. SUBTASK 70-31-13-310-007 Dimensions and Tolerances

    1. Unless other instructions are specified, the standard dimensions and tolerances which follow must control all fusion welding on jet engine parts.

    2. For the thickness of weld metal in groove, flange, plug, slot, arc-spot and arc-seam welds, refer to Figure and Figure. Views show square groove welds but apply to all groove flange, plug, slot, arc-spot and arc-seam welds. Views show only that part of the weld involved.

       1. The height of the weld above the base metal face for groove welds (when the weld is made from one side only) and flange welds (where full penetration is necessary) must agree with the instructions in steps (a) thru (f). Also, refer to these instructions for plug, slot, arc-spot and arc-seam welds for the weld height. When no finish element appears in the welding symbol, these requirements must apply to the metal as welded, but when a finish element appears in the welding symbol, the requirements of step (d) apply. When the surfaces adjacent to the weld bead contain surface alignment variations, the weld metal height measurement must be set from the uppermost surface. Underfill or undercut measurement must be set at each adjacent surface. Refer to Figure.

          1. Some welding symbols have no contour or finish symbol in them. For these, in hand welding, the weld height (above the base metal) must not be more than 100 percent of the base metal thickness. Although, in machine welding it must not be more than 50 percent of base metal thickness. For both types of welding, the undercut or underfill below the surface must not be more than five percent of the base metal thickness. Refer to Figure, View A.

          2. Other welding symbols have a convex contour but no finish symbol. For these, in hand welding, the maximum weld height (above the base metal) must not be more than 100 percent of the base metal thickness. In machine welding it must not be more than 50 percent of base metal thickness. For both types of welding, the maximum weld height must not be less than ten percent. Refer to Figure, View C.

          3. A weld can have a flush contour symbol with no finish symbol. For these, the maximum and minimum weld height above the base metal must be as given in the illustration or the applicable text. Refer to Figure, View E.

          4. A weld symbol can include both the flush contour and finish symbols. For these, the weld height above the base metal must be not more than 0.010in. (0.25 mm) after the weld is finished. The welded joint thickness (this does not include melt-through) after the weld is finished must be not less than the minimum thickness specified for the base metal. Refer to Figure, View G.

          5. When groove welds are made at both faces of the base metal, the requirements of step (1) apply to the weld made on each face of the base metal.

          6. When a groove weld is made at one face of the base metal and a back or backing weld at the opposite face, the requirements of step (1) must apply to the groove weld. The requirements of paragraph D. must apply to the back or backing weld when no finishing is specified. The requirements of step (d) will apply to the back or backing weld when finishing is specified.

             NOTE

             Melt-through is a condition that must be kept to a minimum.

       2. Melt-through is the weld metal on the rear side of the base metal (the opposite side to where the weld is made). The requirements that follow apply to the melt-through for groove welds (this does not include flare groove welds) and flange welds (this does not include welds where complete penetration is not necessary). When no finish is specified for melt-through, these requirements will apply to the metal as welded. The data is also applicable after the weld is finished (if this is necessary).

          1. When no contour or finish symbol is shown in the welding symbol for melt-through, the underfill or undercut must not be more than 5 percent and the height of the melt-through must be not more than 50 percent of the base metal thickness. Refer to Figure, View B.

             However, the maximum melt-through thickness of 75 percent of the base metal thickness is permitted as follows:

             * For hand welding of aluminum.

             * For hand welding of all materials with a maximum thickness of 0.040in. (1.016 mm).

          2. Undercut and underfill must be as specified on an illustration for Class 1 welds.

          3. For a welding symbol with a convex contour element (but no finish symbol given for melt-through) the height of the melt-through must not be more than 50 percent of the base metal thickness. The melt-through must have a convex contour. Refer to Figure, View D.

          4. For a welding symbol with a flush contour symbol (but no finish symbol given for melt through) the minimum and maximum melt-through height must be as given in an illustration or text. Refer to Figure, View F.

          5. When the weld symbol has flush contour and finish symbols given for melt-through, the height of the melt-through must be not more than 0.010in. (0.25 mm) after it is finished. The welded joint thickness (this does not include the weld from the welded side) must be not less than the minimum thickness of the base metal after the finish procedure is completed.

          6. Melt-through on corner-joint square-groove welds are acceptable if the height of the melt-through, measured from each member, is not greater than 150 percent of the thickness of the thinner member.

          7. In flange-groove welds, the weld metal build-up on a base metal surface opposite that from which the weld was deposited must be kept to a minimum.

       3. Corner joint welds. Refer to Figure, View I.

          1. Melt-through of corner-joint welds is permitted, if weld thickness is not less than the thickness of the thinner side that you join together.

          2. The corner joint must not be concave.

       4. Total thickness of welds. Refer to Figure, View J.

          1. Total thickness of the welded joint must not be less than the thickness of the thinnest piece.

          2. When a weld is specified to be made by machine and no finish element is specified, the total thickness of the welded joint must not be more than 175 percent of the base metal thickness as welded.

       5. Dissimilar thickness. Refer to Figure, View K.

          1. When you join two different thicknesses of metal, tolerances must be based on the thickness of the thinner piece when a percentage of base metal thickness is involved and must be measured from the plane of the thinner piece.

    3. The size of fillets in fillet welds.

       1. The length of the fillet weld legs must not be less than the size given on Figure. It must not be more than the factor multiplied by the specified size, as follows:

          1. Specified size for aluminum alloys:

             0.080in. (2.03 mm) maximum - a factor of 4.

             More than 0.080in. (2.03 mm) but less than 0.188in. (4.78 mm) - a factor of 2.

             0.188in. (4.78 mm) minimum - a factor of 1.5.

          2. Specified size for all other alloys:

             0.030 in. (0.76 mm) maximum - a factor of 5 (for Lap Joint Fillets).

             0.063in. (1.60 mm) maximum - a factor of 3.

             More than 0.063in. (1.60 mm) but less than 0.188in. (4.78 mm) - a factor of 2. (A factor of 3 for Lap Joint Fillets).

             0.188in. (4.78 mm) minimum - a factor of 1.5.

          3. Measure the leg length from the root of the joint. For the lap joint fillet welds, measure the leg length from the root of the weld.

       2. The throat (theoretical) of fillet welds for titanium and titanium alloys must not be less than half the fillet leg size specified on Figure. For other materials it must not be less than 0.7, multiplied by the fillet leg dimension given. If the fillet leg dimensions given are of not equal lengths, always use the shorter leg dimension, to find the throat dimension.

       3. The convexity in a lap joint fillet weld must not extend above the base metal surface more than 25 percent of base metal thickness. This is necessary for thicknesses of more than 0.050in. (1.27 mm). If the base metal thickness is 0.050in. (1.27 mm) or less, then the convexity must not extend more than 40 percent. Refer to Figure.

    4. The dimension of flange, back or backing welds.

       1. The minimum dimension of the weld must be as given in the illustration or text for each part.

       2. The maximum dimension must be two times the dimension given in the illustration or text. This is applicable for the weld with a dimension of less than 0.188in. (4.78 mm). It must be 1.5 times the dimension if it is 0.188in. (4.78 mm) or more.

    5. The length of welds.

       1. The length of welds must not be more than 30 percent or less than 30 percent from the value given in text or illustration This is applicable when the length given is 0.500in. (12.70 mm) or less.

       2. For specified weld lengths more than 0.500in. (12.70 mm), the tolerances must be a minimum of 0.000 to a maximum of 0.250in. (6.35 mm).

    6. The pitch of intermittent welds.

       1. Pitch (center-to-center distance) of intermittent welds must not be more than 0.060in. (1.52 mm) or less than 0.060in. (1.52 mm) from the value specified in the text or illustration.

    7. The position of fusion arc-spot and arc-seam welds and electron beam spot and seam welds.

       1. The weld centers must be in the center on the overlap or in the correct position given on the Repair illustration. The tolerance must not be more than 0.040in. (1.02 mm) or less than 0.040in. (1.02 mm) from the given position. The weld center must be one half the weld width from the edge of the weld.

       2. The distance from edge(s) or piece(s) which are at a 90 degree angle to the end of the welding line is as follows. It must be not more than or less than 0.040in. (1.02 mm) of the distance necessary on the Repair illustration.

          NOTE

          In welding, the term "alignment variation" replaces the term "mismatch" because:

          - Alignment variation assumes a post-weld condition.

          - Mismatch assumes a pre-weld condition.

    8. Alignment variation. Refer to Figure and Figure.

       1. Alignment variation limits must be Class 2, except for diffuser and combustion case welds and unless specified differently on the illustration or in the text to be Class 1. (Refer to Step.).

          1. Measure as close to the weld bead as possible.

          2. Do not exceed more than one weld width.

       2. Alignment variation (Figure) must not exceed the limits given in Figure as a percentage of the nominal material thickness.

          1. For parts with unequal material thickness, the limits apply to the nominal thickness of the thinner component.

          2. Dimensional inspection of Class 1 welds for alignment variation must be in the post-weld condition.

          3. Dimensional inspection of Class 2 welds for alignment variation must be in the post-weld condition, when possible. For welds which post-weld inspection is not possible, fixturing conditions must be as agreed upon by an IAE Quality Engineer or equivalent Quality Representative.

    9. Finishing.

       1. Finish welds as specified by the applicable welding symbols or instructions given.

       2. Finishing must be by machining or grinding except as permitted in Step (4).

          1. Finished weld must blend smoothly into the surfaces of the pieces joined with no gouging or undercutting of the base metal.

          2. Runout radius must not be less than 0.250in. (6.35 mm) for welds dressed below the base metal.

          3. If a weld in a curved surface is specified to be finished, finishing must be to a contour that has the same contour as the curved surface.

       3. A weld can be finished when finishing is not specified, but the base metal thickness must not be reduced.

          1. When the weld is finished, measure the base metal thickness. This thickness must be within specified limits.

          2. If inspection of base metal thickness is not possible, do not finish weld.

       4. Finishing of weld by rolling or press-forming is permitted.

          1. Such finishing must not cause mushrooming of the weld metal.

          2. Do not use any finishing method in which you hit the weld with a blunt object.

          3. Remove surface defects by machining or grinding before rolling or press-forming.

          4. If rolling or press-forming is used to correct alignment variation, then there must be a subsequent stress-relief at some point in the repair cycle.

16. SUBTASK 70-31-13-310-008 Inert Gas Fusion Welding

    1. General.

       1. Inert gas fusion welding is a gas arc welding process. It uses an inert gas to give protection to the weld area from the atmosphere.

       2. One type of fusion welding is gas metal arc welding (GMAW), formerly called MIG (metallic inert gas) welding. In this type of welding the electrode is consumed, this then becomes the filler material. The electrode wire is usually made of the same material which is to be welded. GMAW welding must only be used when specified in the Repair instructions.

          1. The electrode wire is usually made of the same material which is to be welded.

          2. GMAW welding must only be used when specified in the Repair instructions.

       3. Another type of welding is gas tungsten arc welding (GTAW), formerly called TIG (tungsten inert gas) welding. In GTAW welding, the filler metal is supplied into the weld area. The torch electrode is not used up (non-consumable) and it is made of tungsten. Pure tungsten is used with alternating or direct current to weld aluminum. Thoriated tungsten (tungsten with two percent thorium oxide) is used with direct current for all other alloys.

          1. Pure tungsten is used with alternating or direct current to weld aluminum.

             1. Tungsten-Zirconia (Zirtung, tungsten with 0.25 percent zirconia) is also used with alternating or direct curent to weld aluminium.

          2. Thoriated tungsten (tungsten with two percent thorium oxide) is used with direct current for all other alloys.

             1. Ceriated tungsten (tungsten with one or two percent cerium oxide) is also used with direct current for all other alloys.

    2. Welding atmospheres.

       1. For materials other than titanium, titanium alloys, refractory metals, and refractory alloys:

          1. Gas must be argon of not less than 99.995 percent purity and/or helium of double charcoal refined grade.

          2. In the gas metal-arc process, use of mixtures up to 5 percent oxygen with argon is permitted except for welding precipation-hardenable iron or nickel-base alloys.

          3. In the plasma-arc process and gas tungsten-arc process,the use of mixtures up to 2.5 percent hydrogen with argon is permitted for welding cobalt alloys, and up to 7.5 percent hydrogen with argon is permitted for welding nickel alloys.

       2. For titanium and titanium alloys:

          1. Refer to Step.

       3. For refractory metals and refractory alloys:

          1. Gas must be argon and/or helium of not less than 99.998 percent purity.

          2. This gas must contain not more than 5 ppm free oxygen and not more than 10 ppm moisture.

       4. GTAW Welding.

          1. When welding is done in an open area (that is, not in a building), argon is recommended. Argon has a lower rate of diffusion because of its greater density.

          2. When an enclosed welding chamber or durable clear plastic envelope is used, either argon or helium is satisfactory.

       5. GMAW Welding.

          1. Carbon dioxide is sometimes used for low alloy steel.

          2. Welding is usually not done in an enclosed chamber or envelope.

       6. The high temperatures necessary for fusion welding and the subsequent air cooling give higher hardness and lower ductility in many materials. This can cause cracks in the weld zone. If correct stress-relief is done after welding (this is usually necessary for most materials), it can cause a large decrease in cracks.

       7. GTAW welding is usually used for repair of cracks in jet engine parts. Electron beam welding can be used, usually when a part is replaced or when it is necessary to add a piece of material.

          NOTE

          Welding machines must control the speed and direction of feed of the work in relation to the welding head of the machine and must control the rate of feed of the filler metal used.

    3. Equipment necessary for inert gas fusion welding.

    4. 
       WARNING
       IF AN OXYGEN REGULATOR IS USED WITH ARGON GAS, IT MUST NOT BE USED AGAIN WITH AN OXYGEN CYLINDER. ARGON GAS CAN HAVE OIL IN IT WHICH CAN CAUSE AN EXPLOSION BECAUSE OF OIL IN THE OXYGEN REGULATOR.
       
       CAUTION
       TO PREVENT CONTAMINATION, ALL WELD TOOLING MADE OF COPPER (BACKUP BARS, EXPANDABLE BACKUP SHOES AND HOLD-DOWN CLAMPS) USED FOR THE WELDING OF COBALT, COBALT ALLOYS AND REFRACTORY ALLOYS MUST BE CHROMIUM OR NICKEL PLATED. THE PLATING MUST BE ON ALL AREAS OF THE TOOL THAT CAN TOUCH THE PART DURING ASSEMBLY OR WELDING.

       Inert gas enclosure fixtures, in some cases , a durable clear plastic envelope can be used.

       Fixtures and chills

       Applicable gas regulators and flowmeters

       Ventilation equipment, as necessary

       NOTE

       ESAB bought out Praxair's welding equipment line. Welding equipment specified (or use units with equivalent features and safeguards) is available from the sources that follow:

       6S493.

       96073.

       Refer to the OPCI for names and addresses of these sources.

       1. GMAW welding.

          Airco DC Aircomatic welder or equivalent.

          Aircomatic AH20 or AH35 gun or equivalent.

          Airco wire feeder or equivalent.

          ESAB ST-12 or equivalent machine GMAW torch.

          NOTE

          ESAB bought out Praxair's welding equipment line. Welding equipment specified (or use units with equivalent features and safeguards) is available from the sources that follow:

          40608.

          6S493.

          96073.

          Refer to the OPCI for names and addresses of these sources.

       2. GTAW welding.

          Miller SR-200 DC or AC/DC welder or Airco DC or AC/DC 200 ampere Bumblebee welder or equivalent.

          ESAB HW-9 (pencil type) or equivalent manual GTAW gas-cooled torch.

          ESAB HW-20, with water circulating equipment and ceramic cups with a range from No. 5 to No. 8 or equivalent manual GTAW water-cooled torch.

          ESAB HW-13 or equivalent GTAW water-cooled torch.

    5. Prepare the part for inert gas fusion welding.

       1. 
          CAUTION
          UNWANTED MATERIAL/CONTAMINATION WILL MAKE THE WELDS WEAK.

          1. Clean the part to remove the grease. Refer to the SPM TASK 70-11-03-300-503.

          2. 

             CAUTION

             WIRE BRUSHES WHICH ARE USED TO CLEAN CORROSION AND HEAT RESISTANT STEELS AND ALLOYS MUST HAVE THEIR BRISTLES MADE OF AUSTENITIC CORROSION RESISTANT STEEL. WHEN YOU USE THE WIRE BRUSHES, MAKE SURE ALL THE UNWANTED MATERIAL IS REMOVED FROM THE SURFACE; IT IS NOT SATISFACTORY TO ONLY POLISH THE SURFACE.

             Use wire brushes or silicon carbide abrasives for rough removal of the protective coatings, unwanted material and surface scale.

          3. Cobalt and cobalt alloys must be cleaned so there is no copper contamination on the surface. Copper contamination can occur if a metalwork operation is done to the part with copper or brass tools/fixtures.

          4. 

             CAUTION

             DO NOT USE CHLORINATED SOLVENTS ON TITANIUM OR TITANIUM ALLOYS.

             Clean areas to be welded. Refer to the SPM TASK 70-11-26-300-503.

          5. Remove all flame plate, plasma spray or other coating or plating in the weld area, which can make the weld weak. This is important when welding because of overspray in the area, applied (with approval) during manufacture or repair.

          6. No unwanted or remaining material must be on the part after it is cleaned.

          7. Prepare the joints as specified by the given welding symbol. Refer to the welding symbol data, dimensions and tolerances for the correct procedure to apply these symbols and the joint preparation.

    6. 
       WARNING
       DURING ALL THESE PROCEDURES YOU MUST OBEY THE SAFETY PRECAUTIONS AND USE APPROVED WELDING PROCEDURES. THERE MUST BE SUFFICIENT VENTILATION AND YOU MUST USE THE NECESSARY PROTECTIVE EQUIPMENT. DO NOT WELD IN CLOSED AREAS UNLESS THERE IS SUFFICIENT EXHAUST VENTILATION.
       
       CAUTION
       DURING GTAW WELDING OF ENGINE PARTS, IT IS MOST IMPORTANT THAT THE WELDING EQUIPMENT GROUND CONNECTION IS ATTACHED DIRECTLY TO THE PART. THE GROUND CONNECTION MUST NOT BE ATTACHED SO CURRENT FLOWS THROUGH THE ENGINE FROM A PART TO A DIFFERENT PART.

       General inert gas fusion welding procedures.

       NOTE

       In GTAW welding, if a sealed welding chamber is used (this can be rigid or flexible), it is not necessary to use cups around the electrode. Also backup fixtures are not necessary. This is only applicable if the air atmosphere is removed from the chamber and it contains only inert gas.

       1. Connect the applicable gas flowmeters to the torch and backup shield, as necessary.

       2. For GTAW welding, install the applicable diameter electrode in the torch. Let approximately 0.31in. (8.0 mm) of the electrode point extend out of the ceramic cup. The dimensions of the ceramic cup control the quantity of inert gas flow to the weld area.

       3. For GTAW welding, gas backing is necessary for the bottom of the weld (this is the opposite side from where the weld is applied) if it is open to the atmosphere. If this is not done, it will result in the usual types of contamination, porosity and welds of unsatisfactory quality.

          1. When this gas protection is necessary, attach an argon gas line to the rear of the crack to be welded.

          2. This can be done if you make a small fixture in the shape of a box. The edges of which have a shape, so the fit between the fixture and the contour agree. Use a Victor 50-20 argon connector or equivalent to hold the line.

          3. Seal the fixture to the part to keep as much inert gas as possible to give protection.

          4. For some parts with internal empty spaces (such as inlet guide vane assemblies or diffuser cases), seal the openings and remove the atmosphere (from all the inner areas) and replace it with inert gas.

          5. You must make a decision on the quantity of pressure to give sufficient backup. This pressure must not permit gas to mix the weld puddle. A vent can help remove the atmosphere from the internal area of the fixture to prevent weld contamination.

       4. In GTAW welding, you must keep a needle point on the electrode, to make sure the arc can be started much easier. This is applicable when there are no high frequency controls available. Also use the procedures which follow:

          1. If it is possible, always keep the electrode clean and make sure there is no material pickup on it.

          2. If necessary, start the arc on a copper plate adjacent to the weld area to prevent arc damage to the part.

          3. Hold the tip of the electrode approximately 0.125 to 0.250in. (3.20 to 6.40 mm) above the surface to be welded until a puddle is made. Add welding wire and weld the part.

          4. You must always use test welds to get the best adjustment of the equipment. The test welds will be made of similar materials of the same thickness and joint design.

       5. In manual GTAW welding with high frequency controls, it is not necessary to hit the electrode on the surface to start the arc. Hold the torch in a vertical position to the workpiece so the shielding gas gives protection on all sides of the weld area. It is better to have the area to be welded in a horizontal (flat) position.

       6. Do not use flux when welding in an inert atmosphere.

       7. If a particular weld Repair tells you to put wet asbestos in the weld area (to keep it cool), the recommended alternative is bulk ceramic fiber. Bulk ceramic fiber (Fiberfrax) can be supplied from:

          Unifrax Corp. (Was The Carborundum Company,Fibers Division,) 2351 Whirlpool Street Niagara Falls, New York 14305, USA Tel: 1-716-278-3800 Fax: 1-716-278-3904

    7. Clean the part after inert gas fusion welding.

       1. Use a rotary file to clean the holes in the part. Polish the holes with No. 180 abrasive cloth.

       2. Clean the part to remove the oxides and discolorations, use the procedure given before in this TASK.

17. SUBTASK 70-31-13-310-009 Plasma Arc Welding

    1. Plasma arc welding (PAW) is a process similar to GTAW. The arc is changed because, as it goes through a constricted orifice, it tightens the arc. This makes a gas stream of straight, highly energized gas or plasma. It is this columnar arc which makes the type of bead related to this process. This bead is of small width and the penetration of more depth.

       When plasma arc welding is used in the 'keyhole' configuration, the intense heat of the high velocity gas goes through the workpiece. As the 'keyhole' is moved along the joint, surface tension of the melted material causes the hole to close. The hole becomes solid (with material) behind the direction of travel.

       The advantages of plasma arc welding compared with GTAW welding include:

       Much better penetration.

       Smaller width of weld bead.

       Decreased shrinkage.

       Decreased joint preparation.

       Decreased amount of filler wire.

       Single pass in machine operation.

       Decrease in passes in manual operation, thus, better weld quality, decreased surface/subsurface defects.

       Decrease width of zone of composition gradient in the weld metal (this can be applicable when the filler wire is not the same as the base metal composition).

       Plasma arc welding is not an interchangeable alternative to GTAW welding. Use only when specified by the Engine Manual.

       NOTE

       ESAB bought out Praxair's welding equipment line. Welding equipment specified (or use units with equivalent features and safeguards) is available from the sources that follow:

       17514.

       40608.

       96073.

       Refer to the OPCI for names and addresses of these sources.

    2. Equipment for plasma arc welding.

       1. The machine plasma arc equipment is as follows:

          ESAB PWC-2 plasma arc welding control.

          ESAB PT-8 plasma arc welding torch.

          Pendant box.

          Junction box.

          Miller analog 300.

          Cold wire feeder.

          Trailing gas shield.

          Positioner or manipulator.

       2. The manual plasma arc equipment is as follows:

          Thermal Dynamics WC-100 control with PWH/M-2A or PWH/M-3A torch or equivalent.

    3. Technical data necessary.

       1. The minimum thickness necessary to make constant keyhole welds in most materials is 0.090 inch (2.30 mm). Some materials can be satisfactorily welded by plasma arc welding when the dimensions are as small as 0.032 inch (0.81 mm).

       2. The maximum thickness of most alloys for machine operation is 0.375 inch (9.53 mm), although the maximum limit for titanium is nearer to 0.500 inch (12.70 mm). For manual operation, the maximum limit is approximately 0.250 inch (6.35 mm). The primary properties which usually limit a particular procedure are the density of the material and surface tension of the molten puddle.

       3. The plasma arc welding process is recommended for use with nickel and titanium base alloys and gives very satisfactory results.

       4. The specific things necessary for each process and plasma torch size must be included in the schedule when you make fixtures. For machine operation, sufficient clearance must be given at the weld joint. This clearance is for the shielding cup and trailing shield with more space to prevent double arcing.

    4. Preparation of plasma arc welding.

       1. 

          CAUTION

          CONTAMINATION AND UNWANTED MATERIAL WILL MAKE THE WELDS WEAK.

          Clean the part to remove the grease. Refer to the SPM TASK 70-11-03-300-503. The surfaces to be welded must not have protective coatings on them which can cause weakness in the weld. Make sure the surfaces have no dirt, grease, oil or other unwanted materials on them, and keep oxides from the part, as much as possible.

       2. 

          CAUTION

          WIRE BRUSHES WHICH ARE USED TO CLEAN CORROSION AND HEAT RESISTANT STEELS AND ALLOYS MUST HAVE THEIR BRISTLES MADE OF AUSTENITIC CORROSION RESISTANT STEEL. WHEN YOU USE THE WIRE BRUSHES, MAKE SURE ALL THE UNWANTED MATERIAL IS REMOVED FROM THE SURFACE. IT IS NOT SATISFACTORY TO ONLY POLISH THE SURFACE.

          Use wire brushes or silicon carbide abrasives for rough removal of the protective coatings, unwanted material and surface scale.

       3. 

          CAUTION

          DO NOT USE CHLORINATED SOLVENTS ON TITANIUM OR TITANIUM ALLOYS.

          Clean the areas to be welded. Refer to the SPM TASK 70-11-26-300-503.

       4. Remove all flame plate, plasma spray or other coating or plating in the weld area. These processes can make the weld weak. This is important when welding because of overspray in the area, applied (with approval) during manufacture or repair.

       5. No unwanted or remaining material must be on the part after it is cleaned.

       6. It is not usually necessary to machine prepare the joint for plasma arc welding, up to the thickness limits of each of the procedures.

    5. Plasma arc welding procedures (machine).

       1. Use the same instructions given for GTAW welding and include the procedures which follow.

       2. If the assemblies have one more surface below and near to the weld joint, they must be fully examined. This must be done before a decision is made to use the plasma arc welding process. The plasma jet has a large quantity of energy, which could melt or cut the adjacent surface (unless a heat shield is used to give protection).

       3. Orifice diameter, gas flow, power adjustment and welding speed must be set for each alloy material and thickness.

          1. The use of too large an orifice will usually make a quantity of extended holes in the weld. This can occur unless the gas flow is decreased until 'keyholing' stops and the arc changes into GTAW mode (then you would not get the properties of plasma arc welding).

          2. The use of too small an orifice will not permit full penetration unless power and gas flow are increased. For these conditions, an action which cuts results, and decrease in orifice life occurs.

          3. Each orifice diameter has an applicable range of thicknesses in which it has an effect. As an example, an orifice dimension of 0.094 inch (2.40 mm) is applicable for a titanium thickness of 0.145 inch (3.68 mm).

       4. Gas protection of the weld puddle and the heat-affected zone is very important with the plasma arc process.

          1. The high-velocity arc jet goes through the workpiece and can make the atmospheric contaminants go into the weld. A sufficient shield gas flow will prevent this.

          2. A trailing gas shield must also be attached to the torch assembly. This gives full protection to the workpiece so no contamination can change the new seam weld during the initial cooldown time.

          3. The gas groove below the joint must have a minimum depth of 0.500 inch (12.70 mm). The width must be sufficient to clear the width of the underbead, refer to Figure.

       5. A test piece of an equivalent material and thickness to the workpiece must be used to get the best gas flow adjustment. This is then used for backup, shield, low flow, high (slope) flow and trailer argon. The position of the workpiece is then adjusted but this must not change the flow adjustment.

       6. Although there is a greater alignment variation tolerance with plasma arc welding, than GTAW welding, the same instructions are applicable. Refer to Figure and Figure.

       7. The electrode must be set in the center of the orifice with a set-up arc (no plasma jet). After the workpiece is installed and set in the fixture, align the weld area visually. Do a test for correct center position of the orifice on the joint with a tackweld using low-flow mode.

       8. Initially the welding current will slope up from a set position on the starting slope current dial to the current value on the welder current dial. This occurs in the length of time set on the starting slope time dial. During this time, travel or wire feed can be started or can be started immediately after the main welding phase occurs. The gas slope system is also started (and stays stable from this time) when the welding arc becomes stable. The 'keyhole' is removed at the end of the finished joint by the gas slope automatic sequence programmer.

       9. The post-flow gas timer controls the flow of post-flow gas and backup gas over the specified area. Functions such as wire feed and carriage drive are controlled by each of the solid-state electronic governors.

       10. Double arcing is usually related to plasma arc, although it is possible on a GTAW torch with a metal gas cup.

           1. For some conditions the arc will not strike directly from the electrode to the work through the orifice. It can go from the electrode to the orifice insert. Then it goes to the workpiece from a different point on the front end of the torch assembly.

           2. The effect of the power decrease in the arc is a decrease in the penetration and an unsatisfactory weld area.

           3. Frequently the secondary arc will make burns in the torch components and the workpiece. There are a number of possible causes for this (these are easy to correct) as follows:

              Insufficient space between torch components and other parts of the work or fixture at ground potential.

              Too high a current for the orifice diameter.

              Too low a gas flow.

              Insufficient torch stand off.

              Incorrect tungsten electrode setback.

       11. Defects or undercuts do not occur frequently but can be repaired easily by machine or manual plasma arc. This is usually after the machine operation sequence is completed.

    6. Plasma arc welding procedures (manual).

       1. Follow the applicable instructions given for inert gas fusion welding and machine plasma arc welding. Also include the procedures which follow.

       2. The electrode is preset to a calibrated distance. The pilot arc is ignited by a high-frequency starting circuit. This heats the orifice argon to make the conductive gas plasma jet.

       3. For titanium, all of the fixture/workpiece must be contained in a durable clear plastic envelope filled with argon. This replaces the trailing and backup gas shields used in machine plasma arc welding.

       4. In welding titanium, use argon or helium for the torch shielding gas, which flows out around the plasma orifice. Refer to Step paragraph 17.A.

       5. For cobalt and nickel-base alloys, the use of mixtures of up to 2.5 percent hydrogen with argon is permitted.

       6. For all other alloys, the gas must be argon of not less than 99.995 percent purity and/or helium of double charcoal refined grade.

       7. Orifice gas (argon) is supplied from two flowmeters, the gas goes into a common hose and duct. One is used as a low flow, the other as a high flow for the 'keyhole' plasma mode. The low flow is only used in 'cosmetic' touchup and repair. The orifice gas can also be supplied from one flowmeter.

       8. Filler wire is optional.

       9. At the end of a manual weld operation, the 'keyhole' is finished by removal of the torch. This usually makes a defect hole which is then repaired with the melt-in (cosmetic) mode.

18. SUBTASK 70-31-13-310-010 Electron Beam Welding

    1. In an electron beam welding machine, the speed of the electrons is increased in an electron gun (to that greater than half the speed of light). The electron flow made is then formed, focused and bent by electrostatic and electromagnetic fields into a beam of small width. This beam hits the material to be welded, as a very small spot. When this occurs, the kinetic energy of the high speed electrons is changed into heat. This melts the material to make a fusion weld.

       The process is usually done in a high vacuum because gas molecules (such as air or a gas blanket) make the electron beam go in all directions.

       At this time there are two basic types of electron beam welders: The high voltage machines which use acceleration voltages of 70,000 to 150,000 volts and the low voltage machines which use from 15,000 to 30,000 volts. High voltage beams can give a beam of better focus with deeper penetration.

    2. A usual electron beam welder, has two basic systems. One system has the electron gun with its related high voltage equipment and controls. The other system has the vacuum chamber, with a number of stages in its pumpdown system.

       1. In the high voltage welders, the electron gun is installed and rigid on the top of the vacuum chamber. The workpiece moves below the beam, inside the chamber, on a controlled motion table.

       2. In the low voltage machine, the gun is moved around inside the chamber over the workpiece (which does not move).

       3. Rotary heads can be used with the low or high voltage machines.

    3. There are three important conditions which give good results with electron beam welding (as compared to the GTAW process).

       1. Low total energy (heat) input.

          This results in minimum distortion, minimum weld area, and minimum heat affected zone. Low heat input is possible because beam penetration is possible without the usual thermal conductivity effects of the weld material (for example in GTAW welding). The accurately focused beam results in a fusion zone with a cross section of small width.

       2. Good control.

          Beam voltage, beam current, spot size and position are all adjustable with precision. This gives control to a high degree of the weld heat input. Also beam deflection in one of two (or both) directions or in the shape of a variable diameter circle can change bead shape and height on some materials.

       3. Metallurgical purity.

          Welding occurs in a very high vacuum, with no oxygen or source of contamination. Also impurities contained in the metal can come out during the time they are changed to gas by weld heat.

    4. General data.

       1. The standards for electron beam welding are the same as for GTAW welding. Although, in electron beam welding, the most usual type of joint is the butt joint. The butt joint must have a close fit with no separation, to give a satisfactory joint. The maximum gap must not be more than 0.003 inch (0.076 mm). Plug welds can be made with this process.

       2. Filler metal is optional. The filler metal is base metal attached over or below the joint with good contact with the parts to be joined.

          1. Filler metal can be strip stock, wire or more material on the inside on one of the parts to be joined. This material can be a snap or pilot diameter on one part. This holds the parts in the correct relation and then is used up as filler material.

          2. Usually where a filler material is used it is necessary to remove material to finish the joint.

          3. The electron beam process must only be used when the Repair in the Engine Manual or the Service Bulletin tells you.

          4. You must be very careful to prevent joint conditions which are unsatisfactory. For example, penetration which is not complete, caused by defective beam alignment or focus. Also, if the beam does not go onto the joint in the correct position specified.

    5. 
       CAUTION
       SPECIAL PREPARATION PROCEDURES WHICH USE ACID CLEANING FOR TITANIUM AND TITANIUM ALLOYS OR THE USE OF CHEMICAL PROCEDURES WHICH REMOVE MATERIAL ARE ONLY PERMITTED IN PARTICULAR WELDING REPAIRS. THESE PREPARATION PROCEDURES MUST NOT BE USED UNLESS SPECIFIED IN THE APPLICABLE REPAIR PROCEDURES.
       CONTAMINATION AND UNWANTED MATERIAL WILL MAKE THE WELDS WEAK.

       Preparation for electron beam welding.

       1. Clean the part to remove the grease. Refer to the SPM TASK 70-11-03-300-503. The surfaces to be welded must not have protective coatings on the them which can cause weakness in the weld. Make sure the surfaces have no plasma spray, flame plate, plating, dirt, grease, oil or unwanted materials on them. Keep oxides from the part, as much as possible.

       2. 

          CAUTION

          WIRE BRUSHES WHICH ARE USED TO CLEAN CORROSION AND HEAT RESISTANT STEELS AND ALLOYS MUST HAVE THEIR BRISTLES MADE OF AUSTENITIC CORROSION RESISTANT STEEL. WHEN YOU USE THE WIRE BRUSHES, MAKE SURE ALL THE UNWANTED MATERIAL IS REMOVED FROM THE SURFACE, IT IS NOT SATISFACTORY TO ONLY POLISH THE SURFACE.

          DO NOT USE SOLVENTS WHICH CONTAIN CHLORIDE ON PARTS.

          Use wire brushes or silicon carbide abrasives for the rough removal of the protective coatings, unwanted material and surface scale.

       3. Clean the area to be welded. Refer to the SPM TASK 70-11-26-300-503, no unwanted or remaining material must be on the part after it is cleaned.

       4. Prepare the joints of the parts to be welded so you get a minimum gap. The gap must not be more than 0.003 inch (0.076 mm). If necessary, machine the parts before welding.

       5. Usually wire filler material can be put at the surface of the joint. When specified, it is necessary to use strip stock filler material of the correct composition to fill the joint. This filler material must be very thin and attached correctly to the joint.

       6. The last step in the preparation of aluminum parts must be an applicable chemical clean procedure before welding.

    6. Electron beam welding procedures.

       1. Install the parts in fixtures or clamp them together as necessary, with filler material if it is to be used. Parts can be carefully tack welded together with inert gas fusion welding with the correct filler wire. These tack welds must not cause defects in the electron beam weld, or base metal. Also the tack welds must be fully contained in the final weld, unless specified differently.

       2. Standard weld symbols and terms used in instructions for specific Repairs must agree with other fusion welding symbols, unless specified differently.

       3. Install a spatter shield (made of the same material as the part to be welded) behind the rear side of the weld. This shield will catch molten weld spatter when it occurs and give protection to the other areas of the parts and equipment.

       4. You must not use flux with electron beam welding.

       5. Adjust the welding machine to give the correct beam power, spot size and routing along the weld.

       6. Schedules of all Repairs made by electron beam welding must be kept available so they can be referred to. These schedules must be made with scrap parts or test parts of similar materials, shapes and thicknesses. This must be done before the welding of flight approved parts.

       7. Monitor the welding process during the operation of the machine. This must be done to find and make correct unsatisfactory defects as they occur. Always obey the manufacturer's instructions for the correct operation of the equipment.

       8. Remove the part from the vacuum chamber then make an inspection of the weld. Finish the weld surface as specified for the particular part. You must be careful to make sure that weld beads on parts in the engine's gas path are of minimum height. They must be correctly flared and if necessary made smooth to prevent an incorrect engine airflow. If these things are not done, it can cause problems in engine operation.

       9. Clean the weld area to remove discoloration. Use the same procedure as in step E. Preparation for electron beam welding.

       10. Stress-relieve the part as specified in the applicable procedure, refer to Step. Stress-relief is necessary because of high temperatures used in the fusion zone of electron beam welding and the subsequent procedure to make the part cool. These procedures can result in an increased material hardness and a decrease in ductility. Although a low total heat is used (in this process), parts can crack unless correctly stress-relieved.

19. SUBTASK 70-31-13-310-018 Powder Feed Weld Surfacing

    1. Powder Feed Weld Surfacing is a welding process used to fuse powder filler metal onto a surface. The filler material is in powder form and the energy source can be either a laser beam or plasma arc which melts the powder and substrate material to produce a correct metallurgical bond.

       The process is performed with an inert gas shield such as argon and/or helium. The nozzle can be either a coaxial or side-feed configuration.

       The advantage of this process over the usual welding process is that the heat input to the base material is kept to a minimum. The result is a very small fusion zone with a minimal heat-affected zone and minimal part distortion.

    2. General.

       1. The applications which do not require Source Qualifications, Power Feed Weld Surfacing can be used as an alternative to GTAW or Plasma to build up weld material if the source agrees to the quality control procedures, refer to para C. and D.

       2. For repairs that requires Source Qualification, contact the manager of IAE Repair Engineering for the requirements.

    3. Surface Preparation.

       1. Degrease the parts, refer to the SPM TASK 70-11-03-300-503.

       2. 

          CAUTION

          WIRE BRUSHES USED FOR CLEANING CORROSION AND HEAT RESISTANT STEELS AND ALLOYS MUST HAVE BRISTLES OF AUSTENITIC CORROSION RESISTANT STEEL. WHEN YOU USE WIRE BRUSHES, BE SURE TO REMOVE ALL THE UNWANTED SURFACE MATERIAL; DO NOT JUST POLISH OVER THEM.

          DO NOT USE SOLVENTS THAT CONTAIN CHLORIDES.

          To remove protective coatings, refer to the repair methods specified in the Engine Manual; then, remove any remaining surface scale by wire brush or silicon carbide abrasives.

       3. Clean the part, refer to the SPM TASK 70-11-26-300-503 solvent wipe method, before you weld.

       4. Make sure there is no remaining material or particles on the parts.

    4. Quality Control.

       1. For non-Source Qualification applications, Powder Feed Weld Surfacing can be used as an alternative to GTAW. You must follow the quality control processes as follows:

          1. Follow the procedures for the specific process control for items such as (but not limited to) those given in steps (b) thru (e).

          2. Powder acceptance testing for composition, purity, mesh size, and gas content.

          3. Welding equipment control and maintenance.

          4. Training and qualification of personnel.

          5. Weld schedule control and general operation.

          6. Destructive testing of test specimens must be done regularly to document weld quality.

          7. General operating procedures must include regular NDT testing (such as FPI and X-ray) of actual hardware.

       2. Guidelines for quality standards as follows:

          1. All quality standards for GTAW applications are specified in the Engine Manual for the specific applications apply.

          2. Cracks must not be more than the quantity permitted for GTAW and must be documented by a metallographic examination during the weld schedule development/review and kept on file.

          3. You can ignore small pores of less than 0.002in. (0.051 mm) when the material thickness is less than 0.063in. (1.60 mm).

             If there is no Engine Manual requirement, the maximum permitted size of pores is 0.020in. (0.51 mm) with 2/linear inch (25.4 mm) and the minimum distance of the indications is 0.080in. (2.03 mm). When applied to castings, the maximum pore size must be as specified in the applicable casting quality documents.

          4. Microcracks, grain boundary melting or other non-crack linear indications.

             Up to 10 indications less than 0.020in. (0.51 mm) in length are acceptable.

             Up to 2 indications greater than 0.020in. (0.51 mm) but less than 0.025in. (0.64 mm) in length are acceptable.

          5. Undercutting is not acceptable.

          6. Make a weld schedule. The welding parameters must not be adjusted more than the tolerances specified as follows:

             1. PLASMA ARC Non-Consumable Type of Inert-Arc Machine:

                Amperage		+/- 10 percent
                Voltage		+/- 2 volts
                Gas Flow		+/- 5 CFH
                Welding Speed		+/- 5 percent
                Powder Feed		+/- 15 percent
                Powder Carrier Gas		+/- 5 CFH

             2. LASER: Power Powder carrier gas 5 percent.

       3. For Source Qualified repairs, quality requirements will be specified in the applicable IAE Engineering documents.

20. SUBTASK 70-31-13-370-001 Stress-Relief After Welding

    1. Usually it is necessary to stress-relieve parts repaired by fusion welding. The cycles of stress-relief operations done in an oven with an air atmosphere are also applicable to local stress-relief operations. Refer to the SPM TASK 70-37-00-370-501.

       For some parts, stress-relief is not necessary. This is known from the satisfactory result of processes done before. The Engine Manual Repair will give the procedure for stress-relief, as necessary.

    2. 

       CAUTION

       THE NECESSARY STRESS-RELIEF (IAE CONTROL NO. 70-37-06, SPM TASK 70-37-06-370-501 AND IAE CONTROL NO. 70-37-07, SPM TASK 70-37-07-370-501) AFTER WELDING OR BRAZING TYPE 410 OR GREEK ASCOLOY MATERIALS REMOVES THE BRITTLENESS IN THE JOINT AREAS. YOU MUST BE CAREFUL WITH THE PARTS DURING THE STRESS-RELIEF PROCEDURE AND UNTIL IT IS COMPLETED. THIS IS TO PREVENT CRACKS IN THE PARTS.

       The stress-relief cycles given in below are for general information. The applicable Engine Manual, Repair or Service Bulletin will instruct the use of a particular stress-relief cycle (these will be identified by the cycle number). If a different stress-relief cycle is necessary (to those given in this procedure) it will be included in the particular procedure.

       Cycle No.		Materials		TASK
       1, 1A		Type 410, Greek Ascoloy, Titanium (Blades) Low Alloy Steels		SPM TASK 70-37-06-370-501 SPM TASK 70-37-07-370-501
       4*, 4A*		Inconel X		SPM TASK 70-37-08-370-501 SPM TASK 70-37-09-370-501
       5, 5A		B-1900/ IAE 633/IAE 1455, STELLITE 31/AMS 5382, Inconel 713/IAE 655, WI-52/IAE653, MAR-M-509/IAE 647, MAR-M-200/IAE 1422/IAE 1480		SPM TASK 70-37-10-370-501 SPM TASK 70-37-11-370-501
       6, 6A		Greek Ascoloy		SPM TASK 70-37-12-370-501 SPM TASK 70-37-13-370-501
       7, 7A		WASPALOY, Udimet 700		SPM TASK 70-37-14-370-501 SPM TASK 70-37-30-370-501
       9		Inconel 600, Nimonic 75/IAE 673		SPM TASK 70-37-15-370-501
       10**		HASTELLOY X, W, N, S Haynes 188/IAE 1042, Inconel 625, Types 310/316		SPM TASK 70-37-16-370-501
       11		Titanium and Titanium Alloys		SPM TASK 70-37-17-370-501
       12, 12A		Inconel 718 Short Cycle Precipitation Heat Treatment		SPM TASK 70-37-29-370-501 SPM TASK 70-37-01-370-501
       13		17-7PH Austenite Conditioning, Types 410/430 welded with 430 Rod		SPM TASK 70-37-18-370-501
       14		Type 430 with AMS 5776 or AMS 5680 Rod		SPM TASK 70-37-19-370-501
       15,*** 15A***		A-286 Tinidur Stress-Relief/Age		SPM TASK 70-37-20-370-501 SPM TASK 70-37-25-370-501
       16		Inconel 706 or 718 Simple Stress-Relief		SPM TASK 70-37-21-370-501
       17		Incoloy 901 (Structural Welds)		SPM TASK 70-37-22-370-501
       18		Cast Nickel and Cobalt Alloy Airfoil Materials		SPM TASK 70-37-26-370-501
       -		Martensitic Corrosion Resistant Steels		SPM TASK 70-37-28-370-501
       -		Types 321/347 (Partial Stress-Relief)		SPM TASK 70-37-31-370-501
       * Cycles 12, 12A and 16 can be used as alternatives to Cycle 4 and 4A.
       ** Cycle 22 (Refer to the SPM TASK 70-37-24-370-501) can be used as an alternative to Cycle 10 for Hastelloy X. Refer to the SPM TASK 70-37-24-370-501.
       *** Cycle 16 can be used as an alternative to Cycles 15 and 15A.

21. SUBTASK 70-31-13-310-012 Welding of Titanium

    1. For good quality GTAW welding on titanium and titanium alloys, it is necessary that no contamination occurs in the weld area, during welding. The inert gas used must be argon and/or helium of not less than 99.995 percent purity. It must not contain more than 5.0 ppm free oxygen and not more than 10 ppm moisture.

    2. Titanium can make oxides and nitrides quickly because it absorbs atmospheric gases/surface contamination at temperatures of 1500 deg F (816 deg C) or more. The result of this is a permanent decrease in fatigue life, tensile strength and ductility. Because the molten weld puddle temperature is approximately 2600 deg F (1427 deg C), the weld bead and some of the heat affected zone can get this contamination. Thus, it is most important that a satisfactory inert atmosphere gives protection on the front and back of the weld. As much as possible, no oxides, dirt, oil, contamination or unwanted material must be on the front or back surfaces (this includes fingerprints on the cleaned metal surface; fingerprints can cause weld contamination which can cause cracks).

    3. After the part is cleaned (in the specified procedure), make sure all the weld area is fully dry with no remaining solution on it. If not, when weld heat is applied, contamination of the gas shield occurs, as the solution changes to a vapor. Put the part in an oven at a temperature of 285 to 315 deg F (141 to 157 deg C) for one hour to dry the internal parts of case assemblies.

    4. Silcon carbide abrasives must only be used for the last surface clean procedure and to remove oxides. This must be followed with a solvent flush. Refer to the SPM TASK 70-11-26-300-503.

    5. It could be necessary to rout the defective area to be welded to make the smallest possible hole. This could be necessary if you cannot gain access to the back of the weld area to clean it. It is then possible to use a mechanical procedure to clean the bottom of the adjacent area. The access hole is then included in the area to be repaired. You can weld a small patch to fill the hole.

    6. It is recommended that the welding of titanium is done in a sealed chamber, pressurized with inert gas. Let a flow of the inert gas go through the hollow parts (such as inlet guide vane assemblies) so the atmosphere is removed. Refer to Step, Inert Gas Fusion Welding. Sufficient time must be given for the inert gas to replace all the air inside each part. You can use a vacuum pump to remove the existing atmosphere in the sealed chamber before the inert gas goes into the chamber. Use this procedure until the atmosphere is of the necessary purity in the chamber.

    7. If a sealed chamber is not available, you can seal the component case holes with plugs. Then, let a flow of inert gas go into the component so the flow goes through or out of the weld area. If necessary, put the gas in one side of the repair and make a small vent on the other side to do this. Always give sufficient time for the air to be replaced.

       NOTE

       The different shades of blue you can see on the welds and the case after this stress-relief are not important. They are caused by the heat of the stress-relief. The colors are not an indication of, pre-weld contamination.

    8. The inert gas purity level can be seen from the color made when the spot welds are made on titanium test pieces (in the sealed chamber). Put the test piece adjacent to the area to be welded so its sides are open to the inert atmosphere. You can bend the test pieces or use clamps or other applicable procedures to do this. The tack welds change in color as the oxygen content decreases and the inert atmosphere becomes more pure (slowly and continuously) as follows: blue, light blue, yellowish blue, yellow, straw, light straw and silver.

       These colors are only applicable to the center of the tack weld. The blue band of small width, which is usually in the heat affected zone, is to be ignored. It is important to get tack welds of a silver color, these must be made on the test piece, before the welding repair is started. You can have the color limit of light straw, refer to IAE 3P16233 and the permitted visual inspection limits. These limits are applicable before the post-weld stress-relief.

    9. When titanium welding with a local inert gas shield, make sure the weld area on both sides has protection. This is applicable until the temperature decreases to approximately 1100 deg F (593 deg C). This is below the temperature when impurities and oxygen becomes absorbed. When a sealed chamber is not used, let the torch gas flow over the weld area for five to ten seconds after the arc is stopped. This will give the necessary gas shield while the weld area becomes cool.

    10. Stress-relieve the parts after welding with cycle No. 11 Figure unless specified differently (Refer to the SPM TASK 70-37-17-370-501).

22. SUBTASK 70-31-13-310-013 Application of Fusion Weld Type Hardfacing

    1. Apply hardfacing with inert gas fusion welding processes to prevent weld contamination.

    2. Use the procedures which follow to minimize the dilution of hardface with parent metal.

       1. Use the smallest diameter hardface weld wire, AC mode and minimum heat. Do not stay in one position on the area for a longer time than is necessary. To get the maximum hardness, you must apply the hardfacing in thin layers.

       2. Use small beads of decreased width, to apply a thin layer of hardface to seal the area. Keep the arc travel to melt the overlay material and not the base material. Let the part become cool.

       3. Grind off about 50 percent of the layer thickness. This is because there will be some dilution with a reduction in the hardness of hardfacing.

       4. Use small beads of decreased width to apply one more layer of hardfacing on the initial layer. Keep the penetration to a minimum to give a decrease in dilution. Grind off about 50 percent of the thickness of this layer.

       5. Apply one more hardface layer, as given before, to get the necessary build-up.

       6. Clean the part then make an inspection of the hardface. Machine the part as instructed.

23. SUBTASK 70-31-13-310-014 Patch-type Weld Repairs

    1. To keep distortion to a minimum for patch-type weld repairs, use a close fit between the patch and the cut-out in the part. Also, use a small diameter weld wire (as less heat is necessary, this gives less distortion). It is satisfactory that more than one pass is necessary when a small weld wire is used.

    2. Correct use of these procedures is important when an adjacent flange or surface has a critical tolerance (for example, flatness, squareness, parallelism, concentricity or a smaller tolerance). The nearer a patch repair is to a critical area the more important step A. becomes. If patches are not as near to such areas and areas with greater tolerances it is not as applicable.

    3. The sequence of welding patches into place can change distortion. Refer to Fig. 70-31-13-990-009, which shows an example of a weld repair patch. Use the procedure which follows for these repairs.

       1. Cut out the area of the part which is to be repaired. Use rounded corners.

       2. Make a patch of the correct material and thickness. Preharden the patch so it is the same hardness as that of the part. Shape the part to the correct contour. Use rounded corners so it agrees with the radius of the cutout.

       3. Keep a small gap, as given before. When a close tolerance fit is necessary, remove a small quantity of patch material at a time and try the fit. Do this procedure until the fit is satisfactory. It is recommended that a line-to-line fit gives minimum distortion.

       4. Install the patch in position as shown in Fig. 70-31-13-990-009.

       5. Tack weld along the edge nearest the flange or the other critical surface with the specified quantity of tack spots. Keep an equal gap along the three sides as shown. The side of the patch away from the critical area must have no gap initially.

       6. Weld along the edge A to A, this will cause the patch to move to the weld. This makes a gap along side B to B.

       7. Weld from A to B in short distances, weld one side then the other in this sequence.

       8. Complete the repair, weld from B to B.

       9. Make an inspection on the weld for correct dimensions and distortion.

24. SUBTASK 70-31-13-310-015 Skip Welding

    1. Skip welding is a procedure used to keep heat (and thus distortion) to a minimum in the weld area.

    2. In general, skip welding is welding a short distance in a location (for this example, weld A) then welding in a location 180 degrees away (weld B). One more weld is then made (weld C) 90 degrees from the initial weld (weld A). This is followed by one more weld (weld D) made at 180 degrees from weld C.

    3. Subsequent welds are then made between two of the welds made in the step B. above, followed by a weld 180 degrees away and so on. The procedure then continues as given in step B. until the weld is completed.

    4. Permit some time between welds so heat is kept to a minimum.

    5. Skip welding or a skip welding pattern will be specified in the Repair given in the Engine Manual.

    6. There are limits in the use of skip welding. For example, when welding projections on a circle, where there is a space between each projection. The use of skip welding has shown that this type of welding can result in more distortion. Because heat is decreased to zero very quickly and the part heats and cools quickly, warpage results. In such a repair, it is better to weld these type of projections one after the other. This permits the subsequent area to become warm gradually. Also at the same time (in the welded area) there is a decrease in the rate the part cools.

25. SUBTASK 70-31-13-310-016 Welding Near Flanges

    1. Welding near a flange frequently results in distortion of the flange. Usually the flange moves permanently in the direction of the weld.

    2. This distortion can be kept to a minimum with use of a welding fixture which can hold the flange. The fixture must be sufficiently flat and strong to keep its shape with the great pressure put on it.

    3. Before welding, measure the flange for flatness, calculate location and quantity of deviations which are found.

    4. When the part is installed in the fixture, it is permissible to use shims between the fixture and flange. This is to put stress on the flange with a sufficient quantity and in the opposite direction, to keep distortion to a minimum. On completion of welding, the part is released (so there are no stresses on the part). The flange area near the weld will go back to its correct plane.

       1. Do not try to put stress on the flange which results in movement of more than 0.020in. (0.51 mm). This is applicable for a distance of 8in. (203.20 mm) on the flange or more than 0.060in. (1.52 mm) in a distance of 24 inches (609.60 mm).

       2. The maximum shim thickness must not be more than 0.060in. (1.52 mm).

    5. Welding near a flange can change the concentricity and roundness of a flange. Usually flanges which are held to a welding fixture with a mating diameter (which gives a tight fit with the flange diameter, or an adjacent diameter) will keep their shape with a minimum of distortion.

    6. Welding fixtures must have a large mass so they can absorb as much heat as possible.

    7. When welding in a particular area near a flange, you can put bulk ceramic fiber around the weld area. This will absorb the heat.

26. SUBTASK 70-31-13-310-019 Rewelding

    NOTE

    The operations that follow can be done in or adjacent to the fusion zone if all the heat treat requirements are fulfilled once no more welding is to be done. Refer to Figure.

    1. Rewelding of manual or machine gas metal-arc, gas tungsten-arc, plasma-arc or shielded metal-arc welds can be made by the initial procedure or the manual gas tungsten-arc or plasma-arc procedure. For class 1 welds, a maximum of three rewelds is permitted for each rejectable indication. Such indications, separated by less than 1.0in. (25.4 mm) must be considered a single rejectable indication.

    2. One reweld of up to 100 percent of the linear length of machine gas metal-arc, machine gas tungsten-arc, machine plasma-arc or electron beam welds can be made by the procedure used for the initial weld.

    3. Manual rewelding of welds initially made by a machine welding procedure is permitted, if the reweld is not more than 25 percent of the linear length of the welds (this does not include drum rotor and rotating knife-edge airseals).

    4. One manual reweld of up to 100 percent of weld length of electron beam welds with gas tungsten-arc or plasma-arc procedure, which uses filler metals specified in Figure, is permitted for filling surface defects, (this does not include drum rotor and rotating knife-edge airseals).

    5. It is permitted to reweld orbital welded tubes two times, if the joint is rewelded to agree with approved welding schedules.

    6. Reweld preparation can include the filling of holes and voids (this includes routed-out defects) by the manual gas tungsten-arc or plasma-arc procedure with the specified base metal or equivalent filler metal.

    7. It is permitted to reweld from the two sides of the weld.

    8. All dimension, tolerance and penetration requirements necessary for the initial weld apply after rewelding.

    9. The width of the reweld plus the remaining part of the initial square groove or prepared groove weld must not be more than two times that of the initial weld.

27. SUBTASK 70-31-13-310-020 Post-Treatment

    1. Assemblies that contain parts that were preheated before welding must have their temperature decreased very slowly after rewelding. If pre-heating was done in a furnace, it is recommended to decrease the temperature of the parts while they are in the furnace.

    2. After welding, keep refractory metal or refractory alloy parts in the protective welding environment until the temperature of the part is less than 350 deg F (177 deg C).

    3. After welding, it is necessary to remove flux (if used) as fully as possible by applicable means. If total removal is not possible, apply a suitable treatment to the assembly to prevent corrosion by the remaining flux.

    4. To clean oxides and discoloration from welded parts, refer to Step or Step or Step, as applicable. Refer to the SPM TASK 70-11-06-300-503 for the cleaning of titanium and titanium alloy parts and heat treating refer to the SPM TASK 70-37-00-370-501.

28. SUBTASK 70-31-13-310-030 Inspection of Welds

    1. General.

       1. The welder must physically examine the weld for quality, uniformity, undercutting, and cracking. Use 10X magnification, unless specified differently by the Engine Manual.

          NOTE

          Be careful to make sure that the weld beads on gaspath parts are held to specific repair requirements and that they are correctly faired by blending to prevent flow disturbance. Failure to follow this precaution can cause engine operation problems.

       2. Welds must blend into adjacent metal in gradual smooth curves. Under no conditions must the operator reduce the thickness of the base metal.

          NOTE

          During welding near a hole, the metal between the edge of the hole and weld area can melt. This causes "Melt Back", which is the result of lack of metal to absorb the heat of welding and can cause a V-shaped area at the edge of the hole. When this occurs, add weld material and repair the hole and the adjacent area to the initial configuration.

       3. Welds must be sound, clean, and free from unwanted material and internal and external defects that can have a bad effect on the strength of the weld.

       4. Tack welds must not be harmful to the base metal and must not have an effect on the quality of the final weld. Tack welds must be fully contained within the final weld, unless specified differently.

       5. Surfacing welds must show fusion at the interface and back welds must have fusion at the root of the joint.

       6. Plug and slot welds must have fusion at all interfaces and depth of filling must be complete.

       7. Welds must have no excessive surface burning, spitting, and expulsion of metal, unless specified differently in the Engine Manual.

       8. Welds specified by like symbols on a drawing and on a given combination of type and thickness of material must have a substantially even appearance.

       9. Do a fluorescent penetrant inspection of the welded area. Refer to the SPM TASK 70-23-00-230-501. You can also use radiographic inspection to do a check for stress cracks and other defects in the weld or in the metal adjacent to the weld.

Figure: Depth of penetration and bevel angles of prepared welds

Depth of penetration and bevel angles of prepared welds



Figure: Depth of penetration and bevel angles of prepared welds

Depth of penetration and bevel angles of prepared welds



Figure: Welding filler metal data

Welding filler metal data



Figure: Weld symbols

Weld symbols



Figure: Groove weld height control symbols

Groove weld height control symbols



Figure: Fillet dimensions in fillet welds

Fillet dimensions in fillet welds



Figure: Alignment variation limits

Alignment variation limits



Figure: Alignment variation Limits - Percentage of nominal material thickness

Alignment variation Limits - Percentage of nominal material thickness



Figure: Plasma arc welding backup fixture

Plasma arc welding backup fixture



Figure: Stress-relief cycle data

Stress-relief cycle data



Figure: Patch type weld repair

Patch type weld repair



Figure: Illustration of dimensions and tolerances

Illustration of dimensions and tolerances



Figure: Illustration of dimensions and tolerances

Illustration of dimensions and tolerances



Figure: Illustration of dimensions and tolerances

Illustration of dimensions and tolerances



Figure: Brush seal weld

Brush seal weld