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Simulated PWHT of P22 Headers

Simulated PWHT of P22 Headers

Simulated PWHT of P22 Headers

(OP)
We have purchased SA 355 grade P22 pipe in Normalized and Tempered condition. It would be subjected to PWHT at 700 degree C for one hour. Client requires NDE after PWHT. Say there are some repairs, we make the repairs and again PWHT shall be conducted at 700C for one hour.
Design Code is Section VIII-1. Do we need heat treatment of specimens to meet UCS-85 requirements?
In my opinion, yes we need because pipe is not in annealed condition so exemption of UCS-85(f) cannot be taken.

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

Yes, you are correct in your interpretation.

RE: Simulated PWHT of P22 Headers

(OP)
What if the construction code is Section I and rest of all details are the same? because Section I is silent on the heat treatment of test specimens i-e Section I does not contain counter part of UCS-85.
In my opinion, simulated heat treatment is still required in accordance with 2nd paragraph of Preamble or PG-16.1.

Second question is: at what temperature the specimens shall be heat treated, details of production heat treatment are given above i-e 700C for two hours. Would the samples be heat treated at 700C for 2 hours and it meet Code requirements?

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

No, sample or coupon heat treatment is not required for Section I thermal treatment during fabrication. Why? Because pressure parts are designed to operate at elevated temperature service under Section I. Thermal treatment effects on pressure vessel materials designed to operate at lower service temperature service is a whole different viewpoint, and this is why coupons are used to simulate effects on thermal treatment during fabrication. These are two separate code book sections and must be treated, as such.

RE: Simulated PWHT of P22 Headers

(OP)
So under Section VIII Division 1 construction, at what temperature and time the specimens shall be heat treated? at 700C for two hours? the details are as above.I am asking this question of time at temperature because I feel difficulty in interpreting UCS-85(b).

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

I would do a cumlative PWHT of the coupon for 3 hours at 700-725 deg C. This way you have covered 3 PWHT cycles at 1 hour hold time at temperature.

RE: Simulated PWHT of P22 Headers

(OP)
Metengr,

Thank you very much for your valuable comments. One more clarification please, you are heating the coupons for 3 hours just because of forecasting one more repair and one more production PWHT.
Otherwise with all above details, Code is satisfied with 2 hours (more specifically I would say 0.8*2 = 1.6 hours, am I right?

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

Yes.

RE: Simulated PWHT of P22 Headers

(OP)
Dear Metengr,

From where I can see lower transformation temperatures of carbon steels and low alloy steels?

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

ASME B31.1

RE: Simulated PWHT of P22 Headers

(OP)
If, say, P22 header is subject to production heat treatment at 490 degree C for 5 hours, P22 is not purchased in annealed condition.
To meet the requirements of UCS-85(b), P22 specimens shall be heat treated at what temperature? would specimens heat treatment shall be carried out above lower transformation temperature for 5 hours?
As I see UCS-85(b), I understand heat treatment of specimens shall be carried out above lower transformation temp. Please advise.

Nasir
Welding Engineer
DESCON ENGINEERING LIMITED
PAKISTAN

RE: Simulated PWHT of P22 Headers

Fizza453;
To ensure compliance with UCS-85, the original quenched and tempered P22 coupon must be subjected to only the PWHT temperature and aggregate time based on what is being done in production. You should not be considering exceeding the lower critical transformation temperature. The reason for UCS-85 is to confirm the mechanical properties for the quenched and tempered P22 after PWHT. If you were to heat this material above the lower critical transformation temperature it will signifcantly alter the bulk mechanical properties.

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