X65 pipe 1

[GRoberts]

Starting a new weld test on X65 pipe, but don't have API 5L specification. What is the elongation requirement? Is the elongation of X65 20% or greater so that 3/8" thick bends are required?

Thanks

 

[Goahead]

You may wish to see the thread330-144804 in Metal and Metallurgy engineering forum, and also to perform a search.

http://www.welding-advisers.com/

 

[GRoberts]

I have actually seen that thread, which to this point has only brought up more questions, and I'm trying to get some material history from the supplier. We are butt welding martensitic stainless pipe to the X65, and must PWHT, but not sure how X65 will react yet, and what temperatures are allowable.

 

[weldtek]

I have the 2000 Ed. What's the wall thickness?

 

[GRoberts]

18" OD, .685" wall.

 

[weldtek]

Per Table D-1, page 87, for Tensile Test Specimens with an area of .75 sq. in., minimum elongation is 24%, for X65 pipe. UTS, 77,000.

 

[GRoberts]

Thanks,
That's what I need to know!

 

[GRoberts]

Follow up question: We have to weld the X-65 to a part that requires PWHT. I finally got the MTRs for the X-65 pipe, and it appears that the pipe is in the "as-rolled" condition. If the X-65 gets PWHT at 1125F, will that reduce the properties too much? we only have to meet the tensile properties (and bends), CVNs are not required. I cannot get ahold of the mill, as the pipe was customer supplied, and might have been made in Vietnam. Not sure on that one. If we can't PWHT the X-65, we may have to butter-PWHT then weld to X-65 without PWHT, but I'd like to avoid that if I can.
Chem is as follows: .067C, .239Si, 1.59Mn, .044Nb, .001V, .028Al, .015Cu, .018Ni, .184Cr, .002Mo, .022Ti, 66ppm N, .019P, and .003S.
Current mech properties are: 630 MPA tensile, 515 MPA yield, 38% elongation.

 

[metengr]

GRoberts;
Sounds like the obvious, but do you have enough X-65 pipe material to run a coupon with and without PWHT? That would be your best bet. Hot rolled condition does not necessarily imply a normalized condition, other than the pipe was hot worked at some temperature above the lower critical transformation temperature and cooled in air. It might well be that PWHT may have minimal effect on the X-65 tensile properties.

 

[GRoberts]

I was thinking about trying to find out if we have enough pipe to run a simulated PWHT and finding out what happens at that point.

 

[stanweld]

Based on the chemistry provided, the X-65 pipe is most likely thermal-mechanically treated to obtain the 65 ksi Y.S. PWHT will affect the properties; as to how much, only testing will determine. Are you sure that the 1125 F PWHT is adequate for the martensitic stainless steel?

 

[GRoberts]

That is exactly my concern. I am thinking about doing the weld, then using some of the unused areas from the cut-up pipe to do some PWHT testing at different temperatures. Then PWHT the remaining pipe at the determined temperature. The martensitic stainless is A487 CA6NM class A, so the 1125F is normal for that material. I see that in some of our historical data, we have passed bend testing with PWHT as low as 950F. Definately don't want to go that low, but I can probably go lower than 1125F if necessary.