Simulation Testing on grade 65 material

[bmoorthy]

It is customery to use API 5L X 65 grades, A 694 F 60 and 65 grades and A 860 material in the top side piping in offshore industry.

Due to the thickness some of the weld joints require PWHT.

It is also noted that suppliers/manufacturer's of above grades express concern on the Physical (Tensile and Yield values) if PWHT is done on this grades. They say that values will go down when heat treated.


That being the case is it not mandated to ask for physical testing in the simulated heat treated condition.

Does any of Pipe line code specify such requirements?

The material standard does not even address the simulation option in supplimentary requirements?

Are simulation tests asked for in the offshore piping industry?

 

[SJones]

The only problem that generally arises will be with linepipe produced by the TMCP route. Even then, selection of the correct PWHT temperature in consultation with the supplier serves to ameliorate any difficulties. For items that are in the quenched and tempered condition, naturally the maximum PWHT temperature should be below the minimum tempering temperature by some margin (usually 20 deg C).

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/

 

[X65]

We have just been in the centre of 2 PSWHT debates with 2 separate clients.

In the end they both waived PSWHT because the X52 pipe we supplied was in the 'Normalised' condition, although had it been in the 'as rolled' or 'Quench & Tempered' then I am sure we would have had to undertake this test adding weeks on delivery and extra money.

Manufacturers do say that there is a drop in yield and tensile strength once heat treatment takes place (on A860 butt weld fittings) - so why Q & T pipe to get better results in yield and tensile strength? Answer must be that Q & T must be done at a lower temperature?

In short I don't think there is a hard & fast pipeline code but I believe various consstructors have included PSWHT in their specs for piping materials with a wall thickness of 19.05mm (0.750") and over.

No doubt it will be included in PSL3 whenever that happens.

Did you have any questions raised about the welding of 2 separate grades, such as F60 flanges to X52 pipe or WPHY65 fittings to X52 pipe? Availability always depends on market conditions so sometimes this scenario is unavoidable and we have had engineers who simply will not do this and some who feel that it is perfectly acceptable. This problem comes up a lot and would be grateful for your comments/advice.

 

[grampi1]

Beware that for a Q&T fitting per A694, the mill tempering temp may be lower than the code required welding PWHT temp, in which case strength will drop sharply.