SA 420 WPL6 in U stamped Pressure vessel

[bmoorthy]

In a U stamped Pressure vessel SA 420 WPL6 is to be used.
The vessel is required to be postweld heat treated.
There are no requirements to follow other that ASME (That is client specification says "All presure vessel shall be designd and fabricated to ASME Sec VIII Div 1 as per desin data (Design data given)

Question 1:: Noting that ASME Sec VIII Div 1 UCS does not call for simulation heat treatment for P1 material, yet as per the clause 7.4 of SA 420 WPL 6 (As embedded below)Is it necessary (In order to meet the ASME requirement) for the vessel manufacturer to inform the fitting supplier that the vessel is going to be used in a vessel and that the vessel is going to be post weld heat treated and the fitting need simulation heat treatment?

Clause 7.4 from A 420 WPL6
7.4 When the fittings are to be post-weld heat treated after being welded by the purchaser and when so specified in the order, the test specimens shall be subjected to the same post-weld heat treatment. The purchaser shall use the postweld heat treatment shown in Table 2, unless otherwise
specified in the order.

Question 2) Does the words " When specified so" imply an obligation on the part of vessel manufacturer to inform the manufacturer of the fitting?

Question 3) IF the vessel manufactuer does mention the vessel is being heat treated, is it mandatory for the fitting manufacturer to subject the test specimens to the same post-weld heat treatment prior to testing (Even if the vessel manufacturer does not call for Simulated testing).

 

[metengr]

Are the SA 420 WPL6 fittings ordered by the vessel manufacturer directly or by your orgaization since you make reference to a client?

 

[vesselfab]

We have never done it as a code compliance because we do not order the parts direct from manufacture.

We have had to run tests on fittings with multiple heat treat cycles for our client.

 

[SnTMan]

bmoorthy, it is common practice that UCS-78(e) specifically exempts you from simulated PWHT on these standard fttings.

Regards,

Mike

 

[metengr]

UCS-85 (e).

 

[SnTMan]

Yes, sorry, "Why don't people read what they post before they post"

Regards,

Mike

 

[bmoorthy]

Thanks SnTMan:: Actually this issue is actually UCS 85 (e) versus SA 420 WPL 6. I also believe that UCS 85 (e) exemption is to be applied, since we ordered standard B 16.9 dimension fittings. Our view is that, had we ordered a non standard wrought specially designed fitting as per SA 420 then only we need to simulate. We have taken up the matter with the AI for his dispensation.
But our client’s inspector, seem to have a different point of view. While he is an expert in his own right and we respect his knowledge, in this instance, we believe he is flawed by insisting the application of clause SA 420 WPL 6 and calling Simulation testing.

Metengr::
We are construction/Vessel fabrication contractors.

Client places order on us for pressure vessel and provided us with the dsign data. MDMT is -40 Deg C. We procure the material and construct the vessel.

We had placed 2 orders for fittings (Due to delivery constraints)

order 1 on a local trader (Standard SA 420 WPL6), we never mentioned any thing about the PWHT or simulation testing in the order. The trader had stock (SA 420 WPL6 2005 year manufacture)

The certificate that the trader has provides results in N and T condition and also in N & T + 595 Deg C PWHT cycle.

Here there was no issue since the certificate caters to both the simulated and un-simulated condition.

order 2 on manufacturer (From Italy), here again we did not mention any thing regarding PWHT or simulation, just standard SA 420 WPL 6.

The manufacturer provided certificate with the test result only in N and T (Supply condition).

Now prior to PWHT while reviewing the Material certificates (by the client inspector) he has made the observation that the fittings are to have simulated test results (Sighting SA 420 WPL 6 clause).

 

[metengr]

Go back and re-read UCS-85 (e) including all referenced paragraphs. The requirement for exemption to PWHT only applies to standard fittings. In this case, ASME SA 420 indicates these are wrought fittings.

Also, because these wrought fittings are specifically mentioned for low temperature service, PWHT may have an adverse effect on notch toughness. Your client's Inspector is correct regarding PWHT time cycle in SA 420, and this should have been specified at the time the order was placed.

 

[SJones]

I would also say that the inspector is correct (even though I only have ASTM A420 and not SA-420). Subclause 7.4 is clear - certification in the PWHT condition is mandatory if PWHT will be subsequently applied.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[SnTMan]

Well, I am going to have to disagree that these parts cannot be exempted per UCS-85(e) as standard parts under UG-11(a). However my opinion does not govern bmoorthy's situation, and he is going to have to work it out with the client inspector.

While the customer may not always be right, he IS always the customer

Regards,

Mike

 

[metengr]

SnTMan;
Normally, you are spot on with your posts. In this case because of the effects of PWHT on notch toughness behavior, I would not consider these as standard fittings that would be exempt under UCS-85 (e). Also, as stated in SA 420, the PWHT cycle clause (if applicable) must be fulfilled. All requirements of the SA specification must be met, regardless.

 

[SnTMan]

metengr, while I still believe the exemption applies, some further study on my part may be in order.

Regards,

Mike