Nafta Hydrotreating : Hydrogen Blistering in A106?

[Lmarcano]

Hi, recently we carried out a thickness measurement of a PIPE by ultrasonics and find low values respect to the nominal, the problem, hidrogen blistering of a 12 months pipe, probably the pipe was inadecuate A53.
Now the question is, what is the better method or test in order to differentiate a A53 from A106 Gr.B pipes? if The chemical composition is the same.
By other side, you know about A106 Gr.B that has failed by blistering? where begin the critical range of H2S concentration that could be harmful for whatever of those materials?

 

[PAN]

I understand that A106-B is killed steel...A53-B is different. So the chemical composition is different too. There would be at least 0.1%Si in A106-B.

 

[Lmarcano]

PAN, when you test those pipes with a portable PMI (material identification) like NITON, the composition looks identical. In manufacturing, I understand, if a A106 pipe that don't reach the specification for inclusions could be stamped like A53.
Killed don't refer to the process that eliminate inclusions?

Thanks

 

[PAN]

Lmarcano,
You're right. The composition looks identical (PMI result). I believe that A106 is better quality compare to A53 (which is not killed steel). However, I do not have experience about blistering in A106.

In my previous projects, I used A106-B (with very low content of S in steel) as piping material for H2S service. The PWHT also carried out at all weldments.