SSC for Piping with Unknown Hardness Levels? 1

[Corroneer]

Hi Everyone,

I have a length of piping (material falls under P No. 1 in ASME B31.3) that I am currently reviewing the corrosion circuits associated with them. I have noticed that SSC is defined as a possible damage which I tend to agree because the service is sour, but upon reviewing NACE MR0175 I noticed that in A.2.1.4 it says:

Tubular products with an SMYS not exceeding 360 MPa (52 ksi), and pressure vessel steels classified as P-No 1, Group 1 or 2, in Section IX of the ASME Boiler and Pressure Vessel Code (see A.2.2.2), are acceptable in the as-welded condition. For these products, hardness testing of welding procedures may be waived if agreed by the equipment user.

And as you know that P no 1 can be exempted from heat treatment as per ASME B31.3 (Table Table 331.1.3 of 2020 Edition).

1. Are piping considered tubular products as per NACE MR0175 definition, or tubular products refer to upstream and downhole applications? because later in the standard (e.g. in A3.3) it discussed Pipeline Steels and states clearly the hardness levels.

2. Does the statement apply to welds only not the parent material, or both?

3. Can SSC be excluded as a potential damage mechanism although we do not know the hardness of the parent material, HAZ, or the welds?

Regards,
Corroneer

 

[SJones]

1.
See definition 3.22 of ISO 15156-2

2.
See interpretation of Inquiry #2006-01Q1. It's a brave person who waives some sort of hardness verification of either parent material, or welds.

3.
If you are happy to use Figure 1 of Part 2, and find yourself in SSC Region 0, you may convince yourself that you don't have a credible threat of SSC.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Corroneer]

@SJones ... thanks for the reply. For answer 3, I never refer to that figure, if I have H2S, then it is sour for me ... might be over-conservative, but I have never understood that figure or ever found it of any practical use (at least to me)!

For answer 2, Inquiry #2006-01Q1: it says that "For these products hardness testing OF WELDING PROCEDURES may be waived if agreed by the equipment user", does it mean that hardness of weld can be accepted if it is in the as-welded condition? (of course, the parent material is out of the equation and the hardness should be verified)

Regards,
Corroneer

 

[SJones]

3.
Well done - you are absolutely correct. Conservative it may be, but, absolutely as per the interpretations of the "maintenance panel" themselves. Indeed, to me the figure is a waste of time: the service is either sour, or it's non-sour.

2.
The text is, of course, useless. Welds are hardness tested, not "welding procedures," (they won't change the text without a ballot and a vote) The indication is that, even if PWHT, has not been applied, the end user can waive hardness testing for those products. Why they need to put this text in is beyond me; as the document is written, the end user can waive anything they like so long as they are prepared to take responsibility for it.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.