Preliminary Requirements

Safety Requirements

WARNING

WHEN FILLERS WHICH CONTAIN CADMIUM ARE USED, A ROOM WHICH IS OPEN TO THE AIR OR A ROOM WHICH HAS GAS/SMOKE VENTILATORS MUST BE USED. THESE ROOMS MUST AGREE TO THE LOCAL HEALTH AND SAFETY APPROVALS.

WARNING

THIS PROCEDURE INCLUDES THE USE OF SODIUM CYANIDE OR POTASSIUM CYANIDE. CYANIDE SALTS AND/OR SOLUTIONS ARE VERY POISONOUS AND WORK VERY QUICKLY. THEY GIVE OFF HYDRO-CYANIC GAS, WHEN MIXED WITH ACID, WHICH CAN KILL. THE PRECAUTIONS THAT FOLLOW MUST ALWAYS BE OBEYED.

WARNING

CYANIDE SALTS AND SOLUTIONS MUST ALWAYS BE KEPT AWAY FROM ACIDS.

WARNING

IT IS THE RESPONSIBILITY OF THE OPERATOR TO OBTAIN AND OBSERVE THE MANUFACTURERS MATERIAL SAFETY DATA SHEETS FOR CONSUMABLE MATERIALS 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.

WARNING

EVERY POSSIBLE CARE MUST BE TAKEN TO AVOID THE SOLUTION COMING INTO CONTACT WITH THE EYES OR BARE SKIN. PROTECTIVE CLOTHING INCLUDING RUBBER GLOVES AND GOGGLES MUST BE PROVIDED FOR THE OPERATORS WHEN PREPARING AND USING THE SULFURIC OR NITRIC ACID SOLUTION. RUBBER GLOVES SHOULD BE CHECKED REGULARLY FOR PIN HOLES AND REPLACED IF NECESSARY.

SAFETY NOTICES MUST BE PLACED IN A CONSPICUOUS PLACE.

EYE-WASH BOTTLES AND HF BURN JELLY MUST BE PROVIDED AS CLOSE AS POSSIBLE TO THE PLACE OF WORK.

IF SKIN BECOMES CONTAMINATED WITH THE SOLUTION IT MUST BE RINSED WITH COPIOUS AMOUNTS OF CLEAN RUNNING WATER.

ALL BURNS, HOWEVER SLIGHT, SHOULD BE TREATED AT THE NEAREST SURGERY OR FIRST AID POST.

THE SURGERY MUST BE TOLD WHICH SOLUTION (THE ACIDS INVOLVED) HAS CAUSED THE BURN.

WARNING

THE PROTECTIVE CLOTHING SUPPLIED MUST BE USED.

WARNING

FINGER NAILS MUST BE KEPT SHORT AND CLEAN. WASH HANDS FULLY BEFORE YOU EAT, DRINK OR SMOKE.

WARNING

EQUIPMENT WHICH YOU DRINK AND EAT FROM MUST NOT BE PERMITTED IN TO A ROOM WHICH CONTAINS CYANIDE. FOOD MUST NOT BE EATEN IN THE ROOM.

WARNING

CYANIDE MUST BE KEPT IN A LOCKED ROOM. ONLY APPROVED PERSONS MUST HAVE ACCESS TO IT.

WARNING

A CYANIDE ANTIDOTE MUST BE SUPPLIED AND BE EASILY AVAILABLE.

WARNING

THE INSTRUCTIONS GIVEN BY THE SAFETY OFFICER MUST BE OBEYED.

WARNING

CHROMIC ACID SPRAY IS INJURIOUS IF INHALED, CAUSING ULCERS IN THE NOSE AND, IN SOME CASES, PERFORATION OF THE NASAL SEPTUM. CHROMIC ACID SALTS AND SOLUTIONS IN CONTACT WITH THE SKIN MAY CAUSE CHROME SORES, AND ULCERS MAY BE FORMED IF CHROMIC ACID GETS INTO CUTS AND ABRASIONS.

WARNING

CHROMIC ACID MUST NEVER BE USED UNLESS THE FUME EXTRACTION PLANT IS IN OPERATION AND FULLY SERVICEABLE.

WARNING

RECOMMENDED BARRIER CREAM SHOULD BE APPLIED TO THE HANDS AND FOREARMS BEFORE STARTING WORK.

WARNING

PROTECTIVE CLOTHING MUST BE WORN, I.E. GLOVES, OVERALLS, GOGGLES OR FACE VISORS AND SAFETY SHOES OR BOOTS.

WARNING

SMOKING AND THE CONSUMPTION OF FOOD NEAR THE CHROMIUM PLATING BATH ARE PROHIBITED.

WARNING

CUTS OR ABRASIONS WHICH APPEAR NOT TO BE HEALING READILY SHOULD BE REPORTED WITHOUT DELAY TO THE MEDICAL DEPARTMENT.

WARNING

CHROMIC ACID IS STRONGLY OXIDIZING AND ENTAILS SOME FIRE RISK IN THE POSSIBLE SPONTANEOUS COMBUSTION OR ORGANIC MATERIALS SUCH AS RAGS AND SAWDUST WHICH HAVE ABSORBED CHROMIC ACID SOLUTION. SUCH CONTAMINATED MATERIALS SHOULD BE IMMERSED IN A SOLUTION OF SODIUM BISULPHIDE TO NEUTRALISE THE CHROMIC ACID, THE SOLUTION SHOULD THEN BE DISPOSED OF AS SPECIAL WASTE. THE SOLID MATERIAL SHOULD THEN BE RINSED WITH WATER PRIOR TO DISPOSAL.

Procedure

1. SUBTASK 70-31-01-310-001 The Preparation of Surfaces Before Brazing

   1. Measure the parts to make sure that there is a correct joint clearence. The joint clearence must be between 0.0015 to 0.0025in. (0.038 to 0.064 mm) unless given differently in the engine manual.

      1. A joint that is too tight will not braze satisfactorily and a joint with too much clearence will not be easy to fill. It is possible to do larger joint clearences with low-temperature brazing and with the applicable fillers.

   2. NOTE

      The brazing on a mild steel or copper part can be removed by mechanical procedures.

      Remove braze metal from joints which were brazed before.

      1. When a joint has to be brazed again, it is necessary to fully remove the defective braze metal. This is very important when the type of filler used before is not known. To remove the defective braze metal from a part it must be put fully in to the applicable solution given below until the braze is removed.

      2. 
         CAUTION
         DO NOT USE CHROMIC/SULFURIC ACIDS ON COPPER PARTS.

         Chromic/sulfuric acids.

         1. 
            WARNING
            THE PROTECTIVE CLOTHING SUPPLIED MUST BE USED. THIS MUST INCLUDE RUBBER GLOVES AND GOGGLES.
            ACID WHICH GETS IN TO THE EYES MUST BE CLEANED WITH WATER AND MEDICAL AID GIVEN IMMEDIATELY.

            A solution of water which contains:

            1. CoMat 01-023 CHROMIUM TRIOXIDE CrO3(CHROM.ACID) at a concentration of 13.35 oz/gal (100 g/l) of solution and CoMat 01-050 SULFURIC ACID H2SO4 at a concentration of 18g/l or 10 ml/l of solution.

         2. NOTE

            The analysis of the solution is not necessary. The solution must be discarded when it has no effect on the parts.

            The solution is used at a temperature of 59 to 77 deg F (15 to 25 deg C) and can be contained in a mild steel or plastic tank. This solution is not to be used on copper alloys.

      3. 
         CAUTION
         DO NOT USE NITRIC ACID ON COPPER OR MILD STEEL PARTS.

         Nitric acids (HNO3).

         1. Use at 25 percent of the volume (refer to the SPM TASK 70-11-07-100-501).

   3. Put the parts fully in to a neutralizing solution of CoMat 01-030 SODIUM CARBONATE Na2CO3 at a concentration of 9.35 oz/gal (70 g/l) of solution. Remove from the solution and clean with cold water and then clean in hot water which is at a temperature of 185 deg F (85 deg C). Allow to air dry.

   4. NOTE

      If mechanical procedures are used to remove braze material, then it is most important to do operation A again. This will make sure the joint clearance is in the specified limits.

      Crack test the parts by an approved penetrant procedure.

   5. Remove grease, rust, scale or oxide film by the procedures specified in the applicable engine manual or repair scheme.

   6. It is most important that the parts to be brazed are very clean. Brazing must start immediately after cleaning. If there is a length of time between cleaning and brazing then the cleaning must be done again.

   7. Make an equal clearence along the joint by center punching.

2. SUBTASK 70-31-01-310-002 The Fluxing of Surfaces Before Brazing

   1. Mix CoMat 03-003 HIGH TEMPERATURE BRAZINGFLUX or CoMat 03-005 BRAZING FLUX or CoMat 03-008 BRAZING FLUX STAINLESSSTEEL GRADE or CoMat 03-009 LOW TEMPERATURE BRAZINGFLUX with a watered solution of one percent CoMat 01-017 FLUORESCENT PENETRANT REMOVER to make a thin paste. Do not permit the flux paste to go dry. Fast deterioration of fluxes occurs when open to the air. Only sufficient flux paste must be mixed necessary to complete the operation. The flux powder container must be kept closed when not in use.

   2. NOTE

      When flux paste is applied to areas adjacent to a joint that becomes hot, will prevent oxidation on the parts.

      Apply an equal layer of flux paste to the joint surfaces of each part to be brazed.

3. SUBTASK 70-31-01-310-003 The Procedure of Brazing a Component

   1. The recommended filler materials for brazing are CoMat 03-001 HIGH TEMP.BRAZING FILLERWIRE 60/40 or CoMat 03-002 BRAZING FILLER WIRE 60/40 or CoMat 03-004 INTERM. TEMP. BRAZINGWIRE, 24% Ag or CoMat 03-006 LOW TEMPERATURE BRAZINGFILLER WIRE or CoMat 03-007 BRAZING FILLER WIRE (LOWTEMP.).

   2. Assemble the parts for brazing immediately after flux is applied.

   3. Apply constant heat to the joint area by the use of one of the procedures below:

      1. Torch or ring burner, which uses air-coal gas, oxy-coal gas, oxy-hydrogen, oxy-acetylene, air-propane, or oxy-propane flame, which must be set neutral or lightly oxidising.

      2. Eddy current heat by the induction coil procedure.

      3. Put the assembly in to a furnace.

         1. The temperature of the joint area must be increased constantly until the filler material melts and goes in to the joint. Do not let the part become too hot.

         2. When thick and thin parts are to be joined, apply heat to the thicker part and permit the heat to transmit to the thinner part by conduction.

   4. On cylindrical joints the filler materials must be of the pre-formed filler wire, which is installed in to the joint during assembly. No other filler is necessary during the brazing cycle. Refer to the engine manual for the correct pre-formed filler wires and for their correct use.

   5. When pre-formed fillers are used, the heat must be kept applied until the braze filler can be seen at the opposite end to the joint to which the wire was initially installed.

   6. On torch braze joints where filler is to be added by a rod or wire, heat the end of the filler through a flame and insert in to the flux powder. As the joint area temperature increases, put the fluxed filler in to the joint. Apply the filler to one side of the joint only. Keep the heat applied and continue with the filler until braze material can be seen on the opposite side of the joint.

   7. Do not apply filler to each side of the joint because this will not show indication of a good braze.

   8. Any joint that does not show braze filler on the opposite side of the joint to which the filler was applied must be disassembled, cleaned and re-brazed.

4. SUBTASK 70-31-01-310-004 The Procedure of Re-brazing a Component

   1. NOTE

      When a defective braze is made it is necessary to fully remove the defective braze metal. This is very important when the type of filler used before is not known.

      Remove defective braze metal from the parts as given in Step.

   2. Do Step and Step again until the braze is satisfactory.

5. SUBTASK 70-31-01-310-005 The Procedure to Remove the Flux

   1. Permit the assembly to cool after brazing.

   2. Remove the remaining flux as specified in the SPM TASK 70-11-21-100-501.

6. SUBTASK 70-31-01-310-006 The Inspection Procedure of a Brazed Joint

   1. Make an inspection of the assembly to make sure that all the flux is removed.

   2. Make an inspection of the brazed joint to make sure that the filler is continuous on each side of the joint.

   3. Examine the assembly for distortion and make sure that no other unusual defects have occurred during brazing.

   4. Examine internal diameters on pipes and fittings with the use of a flexible probe. A ball can be used which has a diameter of 90 percent of the minimum internal diameter.