Pot Bend Heat Treatment : Induction Bends : B16.49

[nipra03]

Hi,

I would like the opinion of experts here on an issue related to post bend HT for induction bends to ASME B16.49.
A vendor is claiming that post bend heat treatment is not required for certain bends which have been ordered on them & per SR15.1, it does appear to be the case. some of my colleagues are of the opinion that PBHT is mandatory and as a minimum, stress relieving is required. Is this approach correct ?

Material grade X52.

 

[weldstan]

Review B31.1 section 129 for some other relevant info regarding post bend heat treatments.

Your vendor is correct if the bends were ordered to SR15.1.

40 years ago we tested a number of bends made in A-333 Gr 6 pipe that were controlled heated during the bending process. They were tensile tested (room temperature)and impact tested at -50F to permit their use without additional post bend heat treatment. We also tested low temperature, X60 bends in the same manner to preclude post bend heat treatment.

 

[metengr]

This is one of those questions where one is coming in the back door to justify a decision. The issue of post induction bend thermal treatment falls entirely on the user to decide if it is necessary, if the code does not specifically require it. Code requirements are a minimum, and as such, the user needs to fully understand the service environment plays a significant role in how the material should be treated before installation.

 

[nipra03]

Thanks meteng, weldstan.
I agree that the vendor should abide by the terms of the Purchase order.
An issue that concerns me is for this material grade should we insist on having stress relief as minimum HT ?

 

[metengr]

What is the specific application regarding the pipe bends?

 

[nipra03]

main pipeline, liquid service (LVP),above grade & below grade locations, design temp. 40C, design pressure 800 psig.

 

[metengr]

Without knowing specific details related to the process, bend radius, and wall thickness for your pipe bends, I would error on the conservative side and perform a post bend thermal treatment as described in B31.1.