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 70-33-66-300-001 Stripping Procedure

   1. This subtask is deleted. Refer to Step and SUBTASK 70-33-66-110-002.

2. SUBTASK 70-33-66-180-001 Preparation Procedure

   1. Remove the grease and oil by the SPM TASK 70-11-03-300-503.

   2. 

      CAUTION

      CONTAMINATION OF THE GRIT BLAST MEDIA WITH COATING OXIDES AND PARTICLES WILL OCCUR IF YOU DO COATING REMOVAL PROCEDURES IN THE SPM TASK 70-34-18-380-501. COATING ADHESION WILL BE UNSATISFACTORY IF YOU DO THE SPM TASK 70-34-18-380-501 PRE-COATING SURFACE PREPARATION WITH GRIT BLAST MEDIA THAT HAS THIS CONTAMINATION.

      Dry grit blast the areas that are to be stripped to remove oxides from the surface of the coating by the SPM TASK 70-12-09-120-501.

      For parts other than turbine airfoils, it is permitted to do the subsequent procedure to remove the ceramic top coat from multiple layer coatings that have a ceramic coat.

      Abrasive blast with CoMat 05-192 ALUMINUM OXIDE GRIT or CoMat 05-046 ALUMINUM OXIDE GRIT 60 grit aluminum oxide by the procedure in the SPM TASK 70-12-09-120-501 to remove the ceramic top coat. Refer to the SPM TASK 70-12-09-120-501, SUBTASK 70-12-09-120-501.

      It is not permitted to use abrasive blast to remove coatings that are in direct contact with (that is, the part material), such as hardface coatings or bond coatings, because too much erosion of the substrate can occur and cracks will be more difficult to find during FPI.

      Although the SPM TASK 70-34-18-380-501 specifies to use 60 grit aluminum oxide, it is not permitted to do coating removal procedures with blasting equipment that you use for the SPM TASK 70-34-18-380-501 preparation prior to coating. Contamination in the SPM TASK 70-34-18-380-501 abrasive grit with removed coating material will cause contamination of part surfaces and subsequent coating bond problems.

   3. 
      CAUTION
      IF YOU DO NOT CORRECTLY APPLY THE MASKING ON THE HARDFACE THERMAL SPRAY COATINGS, THIS PROCEDURE WILL CAUSE DAMAGE TO THE COATING AND MAKE IT NECESSARY TO REPLACE THE COATING.

      Apply a mask to the part areas that are not to be stripped. Use one of the mask materials in the subsequent list and the applicable procedure in the SPM TASK 70-38-24-300-503.

      1. CoMat 02-021 MASKING WAX COMPOUND.

         1. Before you apply a wax mask, apply CoMat 02-067 STRIPPABLE COATING to cooling holes, slots, edges and other part features that must retain (keep) coating to close (small) tolerances.

            1. CoMat 02-038 MASKING WAX COMPOUND (HIGH TEMPERATURE) High temperature masking wax compound.

            2. Before you apply a wax mask, apply CoMat 02-067 STRIPPABLE COATING to cooling holes, slots, edges and other part features that must retain (keep) coating to close (small) tolerances.

      2. CoMat 02-226 WATERBORNE MASKANT.

      3. CoMat 02-259 CHEMICAL MASKANT.

      4. CoMat 02-370 MASKING WAX COMPOUND.

         1. Before you apply a wax mask, apply CoMat 02-067 STRIPPABLE COATING to cooling holes, slots, edges and other part features that must retain (keep) coating to close (small) tolerances.

      5. CoMat 02-388 URETHANE ACRYLIC, UV LIGHT-CURABLE.

      6. CoMat 02-389 MASKANT, AIRFOIL, UV LIGHT-CURABLE.

   4. Put the parts in the applicable baskets or fixtures.

      1. The baskets and fixtures must be made of polyethylene or polypropylene, or have a full coating (layer) of polyethylene or polypropylene.

      2. Make sure that the parts do not touch each other in the baskets or fixtures.

3. SUBTASK 70-33-66-300-002 Stripping Procedure

   1. Put the parts fully in Solution Code 90 Stripping Solution at 140 to 160 deg F (60 to 71 deg C) for two hours maximum.

      1. Keep the parts fully below the level of the stripping solution and make sure that the parts do not touch each other.

      2. 

         CAUTION

         IF THE SOLUTION DOES NOT HAVE SUFFICIENT AGITATION, THE SOLUTION CAN CAUSE PITS IN LOCAL AREAS OF THE PARTS.

         Use mechanical agitation (corrosion resistant stainless steel solution pump, mixer, or up/down lift) to cause continuous movement of the solution while the parts are in the solution.

      3. When you use this procedure to remove IAE 36095, or IAE 36361, or IAE 36395, or other platinum aluminide coatings, it is permitted to decrease the minimum solution temperature limit to room temperature. The reaction between the solution and the coating is exothermic, which will cause the solution temperature to increase during the strippping operation, and thus it will be necessary to make sure that the solution temperature does not increase to more than 160 deg F (71 deg C). Solution temperatures higher than 125 deg F (52 deg C) will increase very much the reaction rate.

   2. Put the parts fully in clean cold water for 30 seconds minimum to rinse (flush) the parts.

   3. Fully rinse the parts with a compressed air/water-spray. Use clean cold water.

   4. Dry the parts fully. Use this procedure:

      1. Put the parts fully in hot water at 130 to 160 deg F (54 to 71 deg C) until the temperature of the parts is approximately at the temperature of the water to flash dry.

      2. Dry the parts with filtered compressed air if water is remaining on or in the parts.

   5. Dry grit blast the parts to remove oxidation or smut on the parts. Refer to the SPM TASK 70-12-09-120-501.

   6. Put the parts fully in clean cold water for 30 seconds minimum to rinse the parts.

      Fully rinse the parts with a compressed air/water spray. Use clean cold water.

   7. Put the parts fully in Solution Code 90 Stripping Solution at 140 to 160 deg F (60 to 71 deg C) for 5 minutes maximum.

      1. Keep the parts fully below the level of the solution and make sure that the parts do not touch each other.

      2. 

         CAUTION

         IF THE SOLUTION DOES NOT HAVE SUFFICIENT AGITATION, THE SOLUTION CAN CAUSE PITS IN LOCAL AREAS OF THE PARTS.

         Use mechanical agitation (corrosion resistant stainless steel solution pump, mixer, or up/down lift) to cause continuous movement of the solution while the parts are in the stripping solution.

   8. Remove the parts from the stripping solution.

   9. Examine the parts for remaining coating. A dark gray smut shows that there is remaining coating.

      1. If there is remaining coating, put the parts fully in Solution Code 90 Stripping Solution at 140 to 160 deg F (60 to 71 deg C) for 55 minutes maximum.

         1. Keep the parts fully below the level of the solution and make sure that the parts do not touch each other.

         2. 

            CAUTION

            IF THE SOLUTION DOES NOT HAVE SUFFICIENT AGITATION, THE SOLUTION CAN CAUSE PITS IN LOCAL AREAS OF THE PARTS.

            Use mechanical agitation (corrosion resistant stainless steel solution pump, mixer, or up/down lift) to cause continuous movement of the solution while the parts are in the solution.

   10. Put the parts fully in clean cold water for 30 seconds minimum to rinse (flush) the parts.

   11. Fully rinse the parts with a compressed air/water-spray. Use clean cold water.

   12. Examine the parts for remaining coating. A dark gray smut shows that there is remaining coating.

   13. 

       CAUTION

       IF THE TOTAL TIME IN THE STRIPPING SOLUTION IS MORE THAN FIVE HOURS, THE SOLUTION WILL CAUSE TOO MUCH STOCK LOSS (REMOVAL OF PART MATERIAL).

       If there is coating remaining on the parts, do the steps above in this procedure again until the coating is fully removed, but the total time in the stripping solution must not be more than five hours.

   14. Put the parts fully in hot water at 130 to 160 deg F (54 to 71 deg C) to flash dry the parts.

   15. Remove the mask materials. Use the SPM TASK 70-38-24-300-503.