ASME B31.3 Unlisted Components Issue 1

[StoneCold]

Greetings all
I am hoping to get some opinions on a B31.3 piping compliance issue for some existing piping.
I have a bunch of 2” and smaller threaded 304 stainless steel piping. The piping is a maze of short runs with a lot of fittings and valves.
The piping does dual service, part of the time it is filled with a methanol/ethanol mixture and part of the time it has steam in the piping.
Design pressure is 100 psig at 325F

The problem is when I was going over the components I discovered that all the fitting are 150# Cast stainless fittings made to a manufacturers specification MSS-SP-114. That particular specification is not in table 326.1. So that makes all those fittings unlisted components.
When I looked at paragraph 304 I did not see a good way to handle all these fittings. The only route I see is the “we have been doing this for a long time and it works” defense for the use of the fitting and I am not very comfortable with that defense. I wonder if any of you have come across this problem?

The second problem with this piping system is the threaded ball valves in the system do not meet ASME 16.34 or API 608. That makes them another unlisted component. They are only made to the manufacturers standard and rated as a 1000 WOG valve. I am again at a loss on what to do with these ball valves.

I could obviously say this all needs to be torn out and replaced but that will not be very popular, or happen any time soon. So I need a way to justify their use if that is possible.
Thanks
StoneCold

 

[moltenmetal]

StoneCold:

I have seen no rules in B31.3 that require you to use valves per API608 or B16.34. Valves designed and built to neither standard are used commonly in B31.3 piping for normal fluid service.

Similarly, a fitting does not need to conform to an ASME standard to be permitted for use in B31.3 piping. MANY components manufactured to MSS specs are used in B31.3 piping all the time.

I don't think you're interpreting the rules correctly. If you can point to the B31.3 sections you feel you are violating by using 150# cast SS or 1000 WOG valves, please do so and those knowledgeable in B31.3 by chapter and verse will chime in.

 

[metengr]

Here is what B31.3 2008 edition states for unlisted materials

323.1.2 Unlisted Materials. Unlisted materials may
be used provided they conform to a published specification
covering chemistry, physical and mechanical properties,
method and process of manufacture, heat
treatment, and quality control, and otherwise meet the
requirements of this Code. Allowable stresses shall be
determined in accordance with the applicable allowable
stress basis of this Code or a more conservative basis.

You don't need to change out anything as long as the pressure/temperature ratings are within the design conditions for the piping.

 

[LittleInch]

In general the introduction states that "All applicable
requirements of the selected Code Section shall be met."

This includes the sections which list the applicable standards including Appendix E which is a requirement.

That should be the first aim of a designer to design under the code.

However it is always acknowledged that other conditions exists and hence in section 300 under "Intent of code" you find this bit.

(4) Piping elements should, insofar as practicable,
conform to the specifications and standards listed in
this Code. Piping elements neither specifically approved
nor specifically prohibited by this Code may be used
provided they are qualified for use as set forth in applicable
Chapters of this Code.

So yes, whilst you should use the codes stated and hence I disagree with moltenmetal in that regard, the hard cold reality is that many ignore this requirement based on cost and item 4. The issue then is how you "qualify" the differnet part. given that MSs is a known and recognised code then it should be OK, providing that your system meets its minimum requirments for e.g. pressure temperature etc. ditto the threaded ball valves.

Writing a design report or incorporporating these into the design basis can act as a means of qualifying it, but it should be specifically noted as exceptions to the main design code and any restrictions it imposes e.g. max pressure rating different to say #150, incorporated into the design basis. I've seen 31.3 used and then PN16 valves , flanges used, but then the design pressure was stated as 16bar.

It's all about catching the most severe temp and pressure rating from these non quoted standards.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[StoneCold]

Thanks guys for your feedback. Your insites into this is very valuable.

metengr It looks to me like 323.1.2 is looking at unlisted materials, since my material of construction is CF8M (cast 316 ss)that would be a listed material, but not necessarily a listed component.

So the section that seems to be a problem for me is in ASME B31.3-2012 Chapter IV. Standards for Piping Components.

326.1 Dimensional Requirements
326.1.1 Listed Piping Components.
Dimensional standards for piping components are listed in Table 326.1 Dimensional requirements contained in
specifications listed in Appendix A shall also be considered requirements of this code.

So the 150# cast stainless fittings are not in the Table and the 1000 WOG valves are not in the table, so I think they
fall into the next paragraph Unlisted piping components.

326.1.2 Unlisted Piping Components (Cross Reference revised in 2012)
Piping Components not listed in Table 326.1 or Appendix A shall meet the pressure design requirement
described in para. 302.2.3 and the mechanical strenght requirements described in para 302.5

So that leads me to the 302.2.3 section

302.2.3 Unlisted Components
(a) Components not listed in Table 326.1 but which conform to a published specification
or standard may be used within the following limitations.
(1) The designer shall be satisified that composition, mechanical properties, method of manufacture,
and quality control are comparable to the correspoinding characteristic of listed components.
(2) Pressure design shal be verified in accordance with para 304.
(b) Other unlisted components shall be qualified for pressure design as required by para 304.7.2.

I think that the composition of the material is fine, the dimensions match a published specification for the fittings (MSS-SP-114), the valves are manufacturer specific.
The problem I have is at the pressure qualification. MSS-SP-114 provides a temperature and pressure rating, and the valve manufacturer provide a temperature and pressure rating
but it does it provide the proof required in section 304.7.2?

304.7.2 Unlisted Components (First paragraph revised in 2012 ed)
Pressure design of unlisted components to which the rules elsewhere in para 304 do not apply shall
be based on the pressure design criteria of this Code. The pressure design shall be substantiated
by one or more of the following means stated in (a) through (d) below. Note that designs are also required
to be checked for adequacy of mechanical strenght as described in para 302.5 Documentation showing compliance with this
paragraph shal be available for the owners approval.
(a) extensive, successful service experience under comparable conditions with similarly proportioned components fo the same or like material
(b) experimental stress analysis, such as described in the BPV Code Section VIII Division 2 Annex 5F
(c) proof test in accordance with ASME B16.9, MSS-SP-97, or section VIII Division 1 UG-101
(d) detailed stress analysis.......
(e) For any of the above the designer may interpolaged between sizes, wall thicknesses, and pressure classes..........

The only statement that I can really back up is that we have been using these components for 10+ years in this service without a lot of problems.
So I would say that (a) of 304.7.2 is satisfied.
However I know that the wall thickness of the 1000 WOG valves is much thinner than the valves that meet the B16.34 standard.
They obviously hold the required pressure but they are much thinner. (I have know idea what they would be like at 1000 psig as we don't operate there)

So to use these unlisted components can I just keep MSS-SP-114 on file for the cast #150 fittings and the manufacturers data sheet for the valves and call it good?
Then knowingly call them out for use in my piping specifications?
I want to to the correct thing, not only with my existing piping but repairs and new designs.

Regards
StoneCold

 

[metengr]

Looking at this again, my opinion is that you have satisfied the criteria in 304.7.2 for Unlisted Components. So, I believe having this information on file is prudent in the event you are audited either externally or internally.

 

[moltenmetal]

10 yrs of successful application doesn't meet the intent of 304.7.2 a) in your opinion?

1000 WOG 2- and 3-piece CF8M cast stainless steel valves and 150# cast threaded and SW fittings have been around for a lot longer than the 10 years you've apparently been using them. There just isn't an ASME standard for them.

 

[StoneCold]

Thanks guys for your input.
I was surprised that the cast 150# manufacturers standard (MSS-SP-114) was not included in the list of approved standard parts.
As far as the ball valves go there is definitely a range of quality, and you have to try to match your particular process needs against valve quality (price)

I guess if it ain't broke don't fix it.
But this is totally a paper issue.

Thanks
StoneCold