fusion tube welds

By Maggs47 (**)

Date 04-13-2017 16:16

As always, without a spec, this question is impossible to answer.

By Tom Fagan Date 04-13-2017 16:35

SA312 type 316 to the same .065 wall and .109 wall fusion. using ASME B31.3

By 803056

Date 04-13-2017 16:49

What is the fluid service; normal, D, M, high pressure?

Al

By Tom Fagan Date 04-13-2017 17:45

food grade low pressure category D

By 803056

Date 04-13-2017 18:02 Edited 04-13-2017 20:01

There are several common weld discontinuities that are not addressed by ASME construction codes. I suspect the condition of the root surface is one of them. If you look in B31.2 under the section for inspection and examinations, you will find a table listing the limits of the discontinuities that are of concern. If the discontinuity isn't listed, there are no limits or restrictions.

If the fluid service is declared as "high pressure" by the owner, the visual criteria are much more specific and stringent than for normal or category D.

Al

By Tom Fagan Date 04-13-2017 18:09

thanks

By 803056

Date 04-13-2017 20:13

Owners that understand what they are up against usually modify the acceptance criteria of the ASME construction code in the project specifications.

As an example: Section VIII of the B&PV code does not include a specific requirement for undercut. They have a limitation for "base metal thinning due to the manufacturing process", so to clarify many owners add criteria for undercut and they include a definition of the condition.

Another example that comes to mind is the allowable undercut per B31.1 for Power Piping. The standard is 1/32 inch regardless of the pipe wall thickness. One of our projects utilized 0.035 inch wall tubing. The owner modified the criteria to no more than 10% of the wall thickness, but not to exceed 1/32 inch.

Check the project specifications to see if the owner/engineer modified the code requirements. They can be more stringent than the code, they just can't be less stringent than the code.

Best regards - Al

By Tom Fagan Date 04-14-2017 12:36

Thanks Al