ASTM A928 "as welded" pipe (HT-O)

[EStilli]

Hi everybody, the question:

for a super duplex steel pipe (24"-36") as per ASTM A928 CL.1 UNS S32760, a vendor specifies that:

"The pipes with OD > 600 mm will be delivered in the "as welded" conditions (HT-O)".

Any suggestions about what it implies? Are they giving me something less or something more?
I'm still in a bid phase, so I can align all the vendors on similar basis.

I think this is an interesting question for everybody. Thank you for your help anyway.

 

[SnTMan]

EStilli, I ran into this on S31803 pipe recently. A quick review of A928 shows that least some testing is required to be done after final HT.

I think you would be responsible for final HT and properties.

I had came to the same conclusion in my case, and decided to find another vendor.

thread794-308067

Regards,

Mike

 

[SJones]

You will have to weigh the benefits of heat treatment against the difficulty of maintaining pipe dimensions if a heat treatment is enforced. If your specification includes metallography, Charpy testing and corrosion testing, any ill effects of welding should be identified.

Steve Jones
Materials & Corrosion Engineer

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

 

[metengr]

EStilli;

"The pipes with OD > 600 mm will be delivered in the "as welded" conditions (HT-O)".

Any suggestions about what it implies? Are they giving me something less or something more?
I'm still in a bid phase, so I can align all the vendors on similar basis.

If you review ASTM A 928 it means no heat treatment after welding. In this specification you as the purchaser have options;

Under 6.3 you either specifically state in your PO acceptance for HT-O pipe (no heat treatment) OR as per this specification, the default requirements is heat treated pipe per the requirements in Table 2 of this specification.

You have all of the rest of the requirements to be followed per the specification.

Do you have a copy of A 928???

 

[EStilli]

Yes,
I have a copy of A 928. It clearly states that heat treatment is mandatory after welding. It is a purchaser option to accept in "as welded" condition.

My doubt is about pipe dimensions and thicknesses: we are talking of UNS S32760 pipe with NPS 24-thk 30,96mm and NPS 36-thk 42mm.
The strains are relevant during forming so I deem that heat treatment is important after welding in order to relieve steel.

My doubt remain about to declare "not acceptable" the technical offer of a vendor that deliveres pipe as "HT-O".

 

[metengr]

EStilli;
As long as you did not state in your proposal or purchase order or contract that you waive the post forming and welding heat treatment requirements as per A 928, the material must be supplied heat treated.

If the vendor is simply providing a proposal or quote and no contract commitment has been made to accept unheat treated material, your refusal of material is based on technical concerns with dimensional tolerances and residual forming strains. Am I missing something - if not reject this as welded option.

 

[EStilli]

Interesting matter that, in my opinion, closes the question.

Shell MESC 74/022_2010 states that: "pipe shall be in the solution-annealed condition".

So, as per Shell, pipe in as-rolled condition cannot be accepted.

Guys, this will be a very good point during my "trial" in front of proposal manager!

 

[SJones]

Solution annealing is not stress relieving and if the plate was solution annealed, as it should have been, the pipe will be in the solution annealed condition except for the weld metal and HAZ. Keeping that size of pipe dimensionally stable at 1100 deg C is a big ask. Your call! If other pipe manufacturers are not quibbling, your choice is clear.

Steve Jones
Materials & Corrosion Engineer

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

 

[metengr]

Solution annealing is not stress relieving and if the plate was solution annealed, as it should have been, the pipe will be in the solution annealed condition except for the weld metal and HAZ.

Regardless. Forming solution annealed plate into pipe results in residual cold/warm forming strains within the pipe that could have deleterious effects on corrosion performance in service.

 

[SJones]

Your call! If other pipe manufacturers are not quibbling, your choice is clear.

Steve Jones
Materials & Corrosion Engineer

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