CSA Z662-07 and Stainless Steel

[ivegotgas]

I have a client who is building some surface piping on a water injection system. Code is CSA Z662-07. In the past they have built all of this piping from Sch 80 316/316L material. I was asked to approve a new installation that would be "identical" to the installations they have done for the past 15 years.

I reviewed the old design and found that the thickness of the 316/316L Sch 80 was not adequate for the pressure they were operating, my recommendation would be to up the weight of the pipe to Sch 160 (Sch 120 would do it, but is hard to find) or change materials to Duplex.

It turns out that the reason I am finding that their "legacy" installations do not meet the current version of code is that I applied section 4.3.5.4 "...for pipe made to a specification other than... design pressure shall not exceed the pressure corresponding to 72% of the SMYS"

Obviously my recommendation has caused some concern since they have now noticed that their legacy installations are no longer "code compliant" and their chief inspector has contacted me and informed me that Section 4 does not apply as 4.1.1 specifically says that the section applies to "steel" pipelines and this is a "stainless steel" pipeline.

My first reaction is that this guy is full of BS, but he is more senior than I am, and I want to be sure that I am coming from the right place.

I am hoping that someone can point me in the right direction perhaps someone has access to a CSA Z662 interpretation for this type of application, I have been trying to search but have not had too much success so far.

THanks

 

[brimmer]

I can only offer my opinion as personally this situation has never come up for me, but I agree with your interpretation. The clasue states which piping specs are included, and stainless steels are not included in those listed, therefore design pressure not to exceed 72% SMYS. I beleive this clause was added in 2007, so was not in 2003 code (although I think added for other reasoning along the lines of making sure wall thickness is close) which may explain why their legacy kit is not to this (the code would not be applied retro-actively though, only for new installations). Line is water, not steam correct? If for steam see section 14 of CSA.

 

[SNORGY]

What SMYS are you using, the one for 316 or for the L-grade 316? Could it be as simple as that? You might be OK if you don't allow L-grade in this case?

Regards,

SNORGY.

 

[konman]

Check out Section 1.5. If you are concerned about the pressure containment ability of the old Sch. 80, do an engineering assessment.

 

[ivegotgas]

SNORGY,

I am using the SMYS of 316, the material is dual rated, however we are using the higher SMYS for calculations.

konman,

Thanks for the reference, the issue is that the "legacy" piping was installed using CSA Z662-07, problem is that the engineer that signed off on it, wasn't, in my opinion, familiar enough with the requirements of the code.