Is Flame Spray Build-Up of Stainless Steel Acceptable According to NACE Standards?

This web page presents a question and answer related to the use of flame spray to build up the surface of 316 stainless steel housings with an oversize machined bore.

The Question

Is the process of applying stainless to stainless for remachining to dimension, via flame spray build-up, acceptable and compliant with the NACE Standard MR0175/ISO 15156?

The Answer

The answer provided by NACE states that flame spraying as a coating for corrosion resistance is acceptable within the requirements of NACE MR0175/ISO15156 Part 2 Paragraph A.2.1.5 and Part 3 Paragraph A.1.5.1. In this case, 316 or 316L base materials can be used if they conform to the metallurgical requirements of Part 3 Table A.2 and are used within the environmental restrictions of this table.

However, if the flame spray application is for the replacement of material that will be load-bearing or subjected to tensile stresses, the inquiry is not currently addressed by NACE MR0175/ISO15156. There is no current data to demonstrate that a flame spray coating of 316 SS or 316L SS has the same cracking resistance as the materials referenced in Part 3 Table A.2, which are assumed to be in the cast or wrought conditions.

This question pertains to NACE MR0175/ISO 15156-3 Annex A.1.5.1, and the reference cited is ISO 15156 Maintenance Panel Inquiry #2005-01.

Conclusion

Flame spray build-up of stainless steel is acceptable according to NACE standards for corrosion resistance. However, if the application involves load-bearing or tensile-stressed material, further testing is required to ensure the same cracking resistance as cast or wrought conditions.

For more information, refer to NACE MR0175/ISO 15156-3 Annex A.1.5.1 and ISO 15156 Maintenance Panel Inquiry #2005-01.