Hardness Testing in 1-1/4 Cr Piping

dbsmith · Jun 12, 2003

This question involves welding of 1-1/4 Cr process piping under ASME B31.3. I have a customer who's internal spec calls for hardness testing of 1-1/4 Cr (SA335-P11) welds after PWHT consisting of 3 impressions: one in the base metal; one in the HAZ; and one in the weld crown. I've advised him that the impression in the base metal is of little use, and is a needless expense. The welds will be made using GTAW. 50% of the welds are socket welds, and the balance are butt welds made in material of less than 0.500". Is there any benefit to requiring the base metal hardness test?

aybee · Jun 12, 2003

it keeps the customer happy...big benefit

Metalguy · Jun 12, 2003

Of course! Besides that, he can then compare the BM hardness to the HAZ, and see what you've done via welding.

dbsmith · Jun 13, 2003

Thanks for the response. My premise is that the impression in the HAZ already indicates the effect that welding is having on the base metal. The material specification already provides a range for the base metal, so the test in the field is redundant.

GRoberts · Jun 13, 2003

The base metal test can confirm that the PWHT did not over-temper the base materail and that is did not fall below the minimum specified hardness, if there is one on your particular project.

stanweld · Jun 17, 2003

B31.3 does not require PWHT for the welds that you mention; therefore, hardness testing is not required. Or is PWHT for the service conditions/process per the Customer? In this case it may be beneficial (at least in the Customer's eyes) if only to provide additional information as to the materials response to welding and PWHT and to assure that hardness is below that required for the process conditions.

IF PWHT is not performed, neither B31.3 nor your Customer's requirement apply to hardness checks.

dbsmith · Jun 17, 2003

Thanks for the info. I should have pointed out that the customer's requirement applies to any chrome alloy, and to carbon steel in "Aggressive Environmental Service" such as caustic.

stanweld · Jun 18, 2003

If service is caustic, I would, as an owner/operator, require testing of the 1 1/4 CR material. It too must meet minimum hardness requirements.

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