Welding Dissimilar Metals for Pressure Sensing Devices: Meeting Hardness Requirements

This web page features a question and answer related to welding dissimilar metals for pressure sensing devices. The question seeks clarification on how to apply the hardness requirements when two materials are welded directly together without the use of a third weld-filler metal.

Meeting Hardness Requirements for Each Material

The answer provided by NACE states that the hardness requirements for each material, including both the base metal and HAZ, should be met. However, the standard does not specify requirements for the fusion line hardness between two dissimilar metals with different maximum hardness requirements. Successful laboratory testing in accordance with Annex B of ISO 15156-3 is required for qualification. Qualification based on satisfactory field experience is also acceptable, but must comply with ISO 15156-1.

Improving Table A.1 in ISO 15156-3 Annex A

The answer also addresses the question regarding the improvement of Table A.1 in ISO 15156-3 Annex A by specifying “”A.6″” in the first column for the row designated for “”Diaphragms, pressure measuring devices and pressure seals.”” The NACE MR0175/ISO 15156 Maintenance Panel intends to make this editorial improvement.

Conclusion: Speak with Our Experts in Welding and NACE MR0175

This question pertains to NACE MR0175/ISO 15156-3 Annex A, and the reference cited is ISO 15156 Maintenance Panel Inquiry #2014-04. If you have any further questions or concerns about welding dissimilar metals for pressure sensing devices, please don’t hesitate to speak with our team of experts in welding and NACE MR0175.