Stress Relieving Requirements as per ASME 31.8

[AaCheM]

Hi,

I'm designing pig launcher (sweet service) in accordance to ASME 31.8. Thickness for major barrel is 31.75mm and as per ASME 31.8 (2012) para 825.2, stress relieve is not required because of the thickness is not excess 32mm. But how about my nozzle(long weld neck) with customize thickness 59.51mm? Is it required stress relieve?

 

[chaulklate]

I am not familiar with 31.8 so I may be speaking out of turn here...

Stress relieve is dependent on thickness of weld (not necessarily thickness of steel). So as long as you you do not have a weld in the LWN, you should be ok.

This does not include/exclude any stress reliefs that may be required for the LWN during the manufacturing process.

 

[metengr]

The requirements for PWHT in accordance with Section 825 of ASME B31.8 use the thickness at the weld joint for governing thickness for PWHT. Also, Section VIII PWHT requirements are cited to follow. Example, if the weld joins two materials of similar composition and unequal thickness, the thickness for PWHT will be the thicker of the two materials at the weld joint.

 

[AaCheM]

Hi metengr,

Sorry I'm still confusing.
1) the branch connection material is A694 F65 and the header is API 5L X65. Can I considered it as same material?
2) Do I need to take the branch connection thickness as a governing thickness for PWHT when it weld to the barrel?
3) In my case, the branch connection is slip in to the header. So the joint design will be single bevel at the header (full penetration weld to the branch connection. Do I need to consider full-penetrant weld size as part of the thickness of weld joint?

Regards,
Junior Mechanical Engineer

 

[bernoullies123]

I don't have 2012 but in the 2010 edition 825.3(b) is quite clear and as per your case. ie. thickness of the header governs.