ASME IX WPS with Hardness Testing-Go Beyond Code Requirements?

[croy]

Currently ASME IX requires supplementary essential variables (SEV) only when impact testing is required, I believe. Many of the GTAW WPS we have (for butt and fillet welds, not hard-facing) require HAZ, base metal, weldment hardness testing. Do you think it is a good practice for these types of procedures to voluntarily go beyond ASME IX requirements and use the SEV? I am a little leery of allowing such a wide range of base metals and filler metals when hardness testing is involved, particularly when we come very close to maximum hardness on some of the PQR's.
Also, have there been any discussions within the ASME IX committee to require SEV when hardness limitations are necessary? Any input would be appreciated, thanks.

 

[metengr]

Do you think it is a good practice for these types of procedures to voluntarily go beyond ASME IX requirements and use the SEV?

Reply; Yes, because it depends on the service application. In certain process streams, hardness of the weld and base metal heat affected zones is quite important and must be held to a maximum value to avoid stress corrosion cracking.

Also, have there been any discussions within the ASME IX committee to require SEV when hardness limitations are necessary?

No. Keep in mind that rules in the Code are written to provide minimum requirements. One can always go above and beyond code minimum requirements. The only example I have seen for hardness testing in ASME Section IX concerns temper bead welding. Hardness testing and impact testing are considered essential variables in QW-290.4 to assure that the base metal heat affected zone has been tempered.

 

[croy]

The hardness values are meant to meet MR0175 and API 6A requirements to prevent stress corrosion cracking, as you mentioned. As such, it is very important not to exceed maximum values.