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 70-31-14-310-001 Surface Preparation

   1. If removal of old braze is necessary, send the parts to an approved vendor. These sources are approved to remove gold-nickel from Type 410 Martensitic, Stainless Steel or Inconel X-750 Nickel Alloy base materials.

      1. Names and Addresses.

         Pratt and Whitney Aftermarket Services (PWAS),

         East Hartford Repair Operations (PWAS-EHRO)

         400 Main Street, Well No 14,

         East Hartford, CT 06108-0969 USA

         Tel: 1-860-565-4579

         Fax: 1-860-565-0349

         Fountain Plating Co., Inc.

         492 Prospect Avenue

         West Springfield, MA 01089-4559 USA

         Tel: 1-413-781-4651

         Fax: 1-413-733-8217

         EDM of Texas

         14042 Distribution Way

         Dallas, TX 75234 USA

         Tel: 1-214-241-2501

         Fax: 1-214-247-7879

         Chromalloy Georgia,

         Division of Chromalloy Gas Turbine Corp.

         30 Dart Road

         Newnan, GA 30265 USA

         Tel: 1-770-254-6200

         Fax: 1-770-254-6204

         G.E. Aircraft Engine Services (GEAES),

         Caerphilly Road, Nantgraw

         Cardiff, South Glamorgan

         South Wales, CF4 7YJ

         United Kingdom

         Tel: Unavailable

         Fax: Unavailable

         Ishikawa Jima - Harima Heavy Industries Co.

         2-1 Ohtemachi 2-Chome, Chiyodaku

         Tokyo 100-8182

         Japan

         Tel: 81-42-568-7356

         Fax: 81-42-568-7073

         Israel Aircraft Industries Ltd.

         Bedek Aviation Div.

         Ben Gurion International Airport

         70100, Israel

         Tel: 972-3-9354156

         Fax: 972-3-9358988

         Japan Air Lines Co. Ltd.

         Engine Maintenance Repair Center Overhaul Business Division

         Narita Airport

         Chiba 282-8610, Japan 

         Tel: 81-476-32-4413

         Fax: 81-476-32-2424

   2. Surfaces to be brazed must be clean before assembly. There must be no dirt, grit, oil, grease, or other contamination on the surface. Degrease the parts, if necessary. Refer to the SPM TASK 70-11-03-300-503.

   3. To prepare the surface for brazing, remove scale and oxidation from the surfaces to be brazed by one of the methods as follows:

      1. If material removal is permitted, machine or blend the surfaces by the SPM TASK 70-35-17-350-501 or SPM TASK 70-35-21-350-501.

         NOTE

         When the repair instructions specify the SPM TASK 70-12-08-300-503, you can use the SPM TASK 70-31-20-310-501 as an alternative.

      2. If material removal is not permitted, abrasive blast the surface by the SPM TASK 70-31-20-310-501.

2. SUBTASK 70-31-14-310-013 Apply Nickel Plate

   1. Nickel plate the surfaces to be brazed, if specified.

   2. Nickel Plating Requirements.

      1. For furnace brazing in a protective atmosphere or in a vacuum, surfaces of these materials to be joined by gold-nickel braze alloy must be nickel plated in the braze area. Refer to the SPM TASK 70-33-06-300-503 and Step, (Table 1: Nickel Plating Thickness).

3. SUBTASK 70-31-14-310-014 Clean the Surfaces

   1. Clean the surfaces to be brazed before you assemble the parts. Refer to the SPM TASK 70-11-26-300-503.

      1. Use protection to keep dust and other contamination away from clean parts.

      2. Wear clean gloves when you touch parts, tools, and brazing material to assemble the parts before brazing.

4. SUBTASK 70-31-14-310-002 Post-Plating Diffusion Treatment

   1. This subtask is deleted.

5. SUBTASK 70-31-14-310-005 Brazing Material

   1. Brazing material must be CoMat 03-114 BRAZE FILLER METAL 82Au-18Ni or CoMat 03-115 BRAZE FILLER METAL 82Au-18Ni or CoMat 03-116 BRAZE FILLER METAL 82Au-18Ni unless specified differently.

      1. For tube assemblies, use the wire or strip form of braze filler metal.

      2. For all other parts, use the powder form of braze filler metal together with an applicable binder as permitted in the repair instructions.

      3. For vane and shroud assemblies and other parts for which the use of brazing paste, wire, rod, sheet or strip forms of CoMat 03-255 BRAZING FILLER METAL is permitted, one of the subsequent pastes can be used:

         1. The powder form of CoMat 03-255 BRAZING FILLER METAL together with an applicable binder.

         2. PS 109 gold nickel alloy powder plus nickel powder mixture and paste; refer to Step, Table 2: Nickel Powder Mixture and Paste. The clearance fills better with the use of the nickel powder.

   2. Sufficient brazing material must be put in, or adjacent to, the joint.

   3. Keep the gold brazing materials in compliance with the manufacturer's storage instructions.

6. SUBTASK 70-31-14-310-015 Brazing Stop-Off

   NOTE

   Do not use CoMat 03-474 COATING, BORON NITRIDE, CoMat 03-474 COATING, BORON NITRIDEA, or CoMat 03-474 COATING, BORON NITRIDEB on bonded vanes; for bonded vanes, use only CoMat 03-477 COATING, BORON NITRIDE.

   1. Refer to Step (Table 4: Base Materials And Their Approved Stop-Off Products), for each part and fixture material.

7. SUBTASK 70-31-14-310-003 Flux

   1. Do not use flux for furnace brazing.

8. SUBTASK 70-31-14-310-004 Assembly

   1. Parts to be connected must be assembled so that the clearance between the surfaces to be connected after nickel plating, if used, is within the part tolerance.

      1. A clearance of 0.0015 inch (0.038 mm) on a side is the most satisfactory.

      2. For tube-to-fitting connections, 0.0015 to 0.005 inch (0.038 to 0.127 mm) loose is the recommended fit.

   2. The assembly must be held so that the parts will be correctly aligned after brazing.

   3. 

      CAUTION

      DO NOT LET BRAZING STOP-OFF GET ON THE BRAZE FILLER METAL OR INTO THE JOINTS TO BE BRAZED. IF BRAZING STOP-OFF DOES TOUCH THESE AREAS, THE JOINT WILL BE UNSATISFACTORY.

      Put sufficient brazing filler metal in the joint or as near as possible to the joint.

   4. You can use brazing stop-off on parts and fixtures to prevent the flow of brazing alloy into areas that are not approved for brazing alloy. Refer to Table 4, Step (Table 4: Base Materials And Their Approved Stop-Off Materials), for the stop-off materials that are approved for each part and fixture material.

   5. If you braze the parts in a furnace, attach one thermocouple at the approximate center of the furnace load. Use more thermocouples as necessary to make sure that all of the parts in the furnace are in the specified temperature range for the specified amount of time.

9. SUBTASK 70-31-14-310-006 Joining

   1. Do not use furnace brazing for tube assemblies after you install silver-plated or aluminum details (for example, nuts).

   2. Alloys hardened by heat treatment.

      1. Heat in a furnace with an applicable protective atmosphere or vacuum. Refer to Step, (Table 3: Gold-Nickel Alloy Brazing Atmosphere).

      2. Furnace brazing must not be used when parts have been hardened before, unless directly specified and information to make the material hard again is in the repair procedure.

      3. 

         CAUTION

         AFTER THE BRAZING CYCLE, PARTS MADE OF HARDENABLE MATERIAL MUST GET THE APPLICABLE TEMPER OR HEAT TREATMENT SPECIFIED IN THE REPAIR, OR THE MATERIAL PROPERTIES WILL BE UNSATISFACTORY.

         NOTE

         The high temperatures of a furnace braze cycle will cause parts made of hardenable material to be too hard or too soft. The heat treatment gives the material the necessary hardness.

         After the brazing cycle is completed, make sure that the parts get the applicable heat treatment cycle (for example, tempering or precipitation heat treatment) as specified in the repair.

   3. Alloys not made hardenable by heat treatment.

      1. Alloys not hardenable by heat treatment can be brazed in a furnace. Use an applicable protective atmosphere or vacuum as given in Step, (Table 3: Gold-Nickel Alloy Brazing Atmosphere).

      2. Braze the parts at one of these applicable temperatures:

         1. For AMS 5581, Type 1 parts, the brazing temperature must not be more than 1850 deg F (1010 deg C).

         2. For other alloys, the brazing temperature range must be 1800 to 1950 deg F (982 to 1066 deg C), unless specified differently.

10. SUBTASK 70-31-14-310-009 Brazing Time

    1. Increase the temperature of the parts to the specified brazing temperature, and then keep the parts at this temperature until the brazing alloy melts and the joint forms.

       1. After the brazing alloy melts and the joint forms, keep the amount of time that the parts are at the brazing temperature to a minimum.

       2. The total brazing time must not be more than 30 minutes for each brazing cycle.

    2. For furnace brazing, the brazing time starts when the lowest recording load thermocouple is at the brazing temperature. The brazing time ends when the lowest recording load thermocouple is less than the minimum permitted brazing temperature during the cool-down part of the cycle.

    3. If the furnace load has lagging thermocouples, you can keep the load in the permitted brazing temperature range while the lagging thermocouples increase in temperature. This prebraze hold time must not be more than 30 minutes after 75 percent of the recording load thermocouples are between the limits of the permitted brazing temperature range.

       1. Definition of Terms.

          1. Lagging thermocouples are load thermocouples that are below the lower limit of the brazing temperature range, but still increase in temperature.

          2. Load thermocouples are those thermocouples that directly monitor (that is, do a check of) the temperature of the parts in the furnace load.

          3. The brazing temperature range is the range of temperature from the minimum permitted brazing temperature to the maximum permitted brazing temperature.

          4. The prebraze hold time starts when 75 percent of the recording load thermocouples are between the limits of the permitted brazing temperature range while the lagging thermocouples continue to increase in temperature, and stops when the lowest recording load thermocouple is at the lower limit of the permitted brazing temperature range.

11. SUBTASK 70-31-14-310-007 Cooling

    
    CAUTION
    IF YOU DO NOT OBEY THE COOLING RATE SPECIFIED BY THE ENGINE MANUAL REPAIR INSTRUCTIONS, THE PART PROPERTIES WILL BE UNSATISFACTORY.

    NOTE

    When you use a vacuum furnace, you can add pure argon to the furnace to get the specified cooling rate.

    1. Keep the same brazing atmosphere until the temperature of the parts is less than the scaling temperature.

       NOTE

       Cooling rates specified by the Engine Manual repair instructions can be different from the rates specified by the Standard Practices/Processes Manual (SPM). Always obey the cooling rates specified by the Engine Manual repair instructions.

    2. After brazing, decrease the temperature of the assemblies to 1700 deg F (927 deg C), the braze quench temperature, at a rate that prevents cracks and minimizes the conditions as follows:

       1. Internal stress.

       2. Distortion.

       3. Oxidation.

       4. Decarburization.

       5. Scaling.

    3. For alloys that are hardenable by heat treatment, decrease the temperature of the assemblies from 1700 deg F (927 deg C) to 1100 deg F (593 deg C) at a rate not less than 35 deg F (19 deg C)/minute, and then from 1100 deg F (593 deg C) to 1000 deg F (538 deg C) at a rate not less than 15 deg F (8 deg C)/minute. The cooling rate is optional at temperature less than 1000 deg F (538 deg C).

    4. For alloys that are not hardenable by heat treatment, use the cooling rates that are specified by the Engine Manual repair instructions.

12. SUBTASK 70-31-14-310-016 Inspection

    NOTE

    This condition is not applicable to tube clamp reinforcements, for example: Tube wear sleeve joints, "J" bracket support joints, and bracket-washer joints.

    1. Appearance.

       1. A check of all joint edges that you can see must show brazing metal for 100 percent of each joint.

          1. It must be possible to see braze stain or alloy at one or more edges of the joint.

             NOTE

             You can accept reinforcement joints for tube clamps with 50 percent minimum area joining.

    2. Coverage.

       1. The area connected by filler metal must not be less than 80 percent of the mating surfaces of the assembly.

       2. Use an agreed upon procedure to satisfactorily do this check for coverage.

13. SUBTASK 70-31-14-310-017 Quality

    1. Depth of Braze Joints.

       1. The depth of alloy at the joint must not be more than 0.004 inch (0.102 mm). This depth is measured from the initial base metal surface.

       2. The depth of the undercut must not be more than 0.002 inch (0.051 mm).

       3. The total depth of alloy plus undercut must not be more than 0.004 inch (0.102 mm).

    2. Brazed joints must be strong and clean with no unwanted material or imperfections that can have a bad effect on the performance of the brazed joints.

    3. The surface of the parts must be without pits, burns, or unwanted braze that can cause a problem with form, fit, or function.

    4. Joints must be without cracks or filler metal that did not flow.

14. SUBTASK 70-31-14-310-010 Table 1: Nickel Plating Thickness

    		Nickel Plating Thickness in Inch (mm)
    Alloy		Vacuum	Argon and/or Hydrogen
    Precipitation Hardenable Iron Base Alloys		0.0001 to 0.0006 (0.00254 to 0.01524)	0.0004 to 0.0006 (0.01016 to 0.01524)
    Non-precipitation Hardenable Stainless Steels - Titanium Stabilized		0.0001 to 0.0006 (0.00254 to 0.01524)	0.0004 to 0.0006 (0.01016 to 0.01524)
    Precipitation Hardenable Nickel Base Alloys	(a) Ti+Al Content Less Than 4 Percent Nominal	0.0001 to 0.0006 (0.00254 to 0.01524)	0.0004 to 0.0006 (0.01016 to 0.01524)
    	(b) Ti+Al Content 4 Percent Nominal or Greater	0.0001 to 0.0006 (0.00254 to (0.01524)	0.0008 to 0.0012 (0.02032 to 0.03048)
    Non-Precipitation Hardenable Nickel Based Alloys, Ti+Al Content Up To 1 Percent		Optional 0.0006 (0.01524) maximum	0.0001 to 0.0006 (0.00254 to 0.01524)
    All Other Alloys		Optional 0.0006 (.01524) maximum	Optional 0.0006 (0.01524) maximum
    (1) Nickel plating in areas other than joints is optional and can be incomplete.
    (2) This table replaces Fig. 70-31-14-990-001.

15. SUBTASK 70-31-14-310-011 Table 2: Nickel Powder Mixture and Paste

    Solution No. and Name		Composition						Preparation
    		Material		Make-up percent		Make-up Limits percent
    PS 109 Gold-Nickel Alloy Powder Plus Nickel Powder Mixture and Paste		Gold-Nickel Alloy Powder CoMat 03-114 BRAZE FILLER METAL 82Au-18Ni, CoMat 03-115 BRAZE FILLER METAL 82Au-18Ni or CoMat 03-116 BRAZE FILLER METAL 82Au-18Ni		85		85 to 90		Mixture: 1. Mix 85 parts by weight of CoMat 03-114 BRAZE FILLER METAL 82Au-18Ni, 03-115 or 03-116, with 15 parts by weight of CoMat 03-257 NICKEL POWDER. Total weight mixed at a time must not exceed 15 to 20 oz. wt (425.3 to 567 g). 2. Keep in tightly closed glass jars.
    		Nickel Powder CoMat 03-257 NICKEL POWDER Binder Alloy CoMat 03-256 BINDER, BRAZING ALLOY		15		10 to 15		Paste: 1. Prepare paste immediately before it is applied. 2. To not more than 3 to 4 oz. wt (85 to 113.4 g) of mixture add CoMat 03-256 BINDER, BRAZING ALLOY binder to make a paste. 3. When paste becomes too sticky, add more CoMat 03-256 BINDER, BRAZING ALLOY binder.
    (1) This table replaces Fig. 70-31-14-990-002.

16. SUBTASK 70-31-14-310-012 Table 3: Gold-Nickel Alloy Brazing Atmospheres

    Type		Dew Point See Note (1)		Pressure/Purity		Application See Note (4)
    Vacuum		- - -		5x10-4 torr (0.5 micron Hg) or better. See Notes (2) and (3)		Furnace brazing
    Argon		-35 deg F (-37 deg C) or better		99.99 percent minimum		Vacuum furnace backfill
    Hydrogen		-60 deg F (-51 deg C) or better		99.94 percent minimum		Furnace brazing
    (1) When possible, use the brazing chamber exhaust gas to calculate the dew point.
    (2) The furnace leak-up rate must not be more than 20 microns Hg/hour calculated at room temperature after you pump down to 1 micron Hg pressure or less and block the pumps.
    (3) Partial pressure or argon is permitted if you backfill with argon after you have the necessary vacuum.
    (4) Refer to the SPM TASK 70-31-09-310-501 for vacuum furnace brazing procedures.
    (5) This table replaces Fig. 70-81-14-990-003.

17. SUBTASK 70-31-14-310-018 Table 4: Base Materials And Their Approved Stop-Off Materials

    		Approved Stop-Off Materials
    		CoMat 01-253 SULFURIC ACID ADDITIONAGENT	CoMat 03-471 STOP-OFF, BRAZING	CoMat 03-472 TAPE, BRAZING STOP-OFF	CoMat 03-473 PAINT, BRAZING STOP-OFF	CoMat 03-474 COATING, BORON NITRIDE	CoMat 03-475 COMPOUND, BRAZING ALLOYSTOP-OFF	CoMat 03-476 COMPOUND, BRAZING ALLOYSTOP-OFF
    Steels		X	X	X	X	X	X	X
    Stainless Steels		X	X	X	X	X	X	X
    Nickel-base Alloys		X	X	X	X	X	X	X
    Cobalt-base Alloys		X	X	X	X	X	X	X