Number of thermocouples during PWHT according to ASME section I and B31.1

[JohnWE]

Hello engineers,
I am starting work on boiler pipelines according to ASME section I and B31.1. We will weld pipes with P no. 4, 5A and 15E with quite large diameters (up to 813 mm) and thicknesses (up to 57 mm). In his specification, the client specified the number of monitoring thermocouples (from 1 to 4 depending on the diameter), and there should be exactly as many control thermocouples as heating elements. Considering the large dimensions of the pipes, it results that up to 20 thermocouples should be used. We would have to use 2 annealing machines for 1 weld. Section I and B31.1 also require a large number of thermocouples. What do you think about this? From your experience, what is the approach to the number of thermocouples on projects according to ASME?

 

[hacksaw]

You'll have to explain what your customer means by "heating elements," and the purpose of the measurements.
You may need access to the piping layout drawings to sort out your question.

 

[r6155]

DO NOT DUPLICATE POST.

 

[JohnWE]

@hacksaw
By "heating element" they mean each heating mat. That is why performing PWHT with these guidelines in the case of large diameter pipes requires the use of a large number of mats.

@r6155
Sorry, I wasn't sure which section to ask this question in.