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Welding procedure for welding API 6A (4130 to A106 B)

Welding procedure for welding API 6A (4130 to A106 B)

Welding procedure for welding API 6A (4130 to A106 B)

(OP)
Good afternoon all,
As I understand, many API 5ksi flanges are made of SA105 materials. I plan to have welders weld this to A106 grade B line pipe to transition from from API wellhead to B31.3 flow line.

the WPS has the following essentials, and other variables are:
Root is MIG
fill/cap is 7018 (low hydrogen)
Pre-heat minimum is 175 F
PWHT is 1125 +/- 25F
P1 to P1
thickness range for base metal from 0.1875" to 0.944"
etc.

Can this variables be used to join an API 5ksi (SA 105) material to an A 106 grade B in the shop? as long as the two pipes meet the variables like thickness range, strenght of material, etc. This is a qualified WPS.

Thank you.

 

RE: Welding procedure for welding API 6A (4130 to A106 B)

mysarah;
Your subject line references 4130 to SA 106. In the text of your post you reference SA 106 to SA 105. Confused.

RE: Welding procedure for welding API 6A (4130 to A106 B)

(OP)
I'm sorry, I blame the 2:30 feeling at work, it's not 4130 at all, it's SA 105.
Thanks for pointing out.

RE: Welding procedure for welding API 6A (4130 to A106 B)

No problem. The above welding variables are acceptable for joining SA 105 to SA 106, provided no impact testing/qualification is required.  

RE: Welding procedure for welding API 6A (4130 to A106 B)

Spec the Mig - GMAW wire as ER-70Sx [my personal favorite is ER-70S6] and you are perfect.

RE: Welding procedure for welding API 6A (4130 to A106 B)

(OP)
@metengr:
Thanks metengr!
The reason why I was asking is to find out if the pre-heat temperature of 175F is not too small for a wellhead flange as I transition from wellhead to flow line (2"xxh, 3"xxh, or sch. 160).
Also, since the WPS covers P1 to P1, that means I can also use it for line pipe to line pipe as long as I specify the 175 pre-heat requirement is only for the SA105 wellhead flange to A 106 grade B piping right? because the pre-heat shouldn't be a requirement for the A106 to A106 in the flow line right?

@Duwe6:
The MIG wire is ER70S-6

RE: Welding procedure for welding API 6A (4130 to A106 B)

The 175 F min preheat is more than adequate for the intended welds. Why are you using PWHT for the thinner weldments (< or = to 3/4")? Is H2S present in the fluid?

RE: Welding procedure for welding API 6A (4130 to A106 B)

(OP)
yes, it will be used for both areas with h2s and without, I didn't want to qualify two procedures. This weld in only one butt weld per well. and it's done in the shop only, so it's not a wps that will be used for an entire facility to make pwht expensive.

RE: Welding procedure for welding API 6A (4130 to A106 B)

For P-1 materials like SA-105, A-53,SA-103, etc. the preheat requirements are only driven by thickness.  The 175°F is to compensate for the heat-sink that the thick flange causes.

If a weld cools too fast, it will rip itself apart due to the shrinkage from the decrease in size of the weld bead.  The bead is a LOT smaller at room-temp. than it was when the puddle 'froze' at 2000°-plus.  If it cools slow enough, something 'gives' [bead stretches, basemetal is pulled in], allowing the bead to not tear.  That is the purpose of preheat, to control the rate of cooling of the weld bead.

RE: Welding procedure for welding API 6A (4130 to A106 B)

(OP)
Thanks Duwe6,

so the pre-heat is just enough, but the other point is, for a sour service, the PWHT is not required for thickness below 3/4" but it is a good practice right?

RE: Welding procedure for welding API 6A (4130 to A106 B)

Correct on the pre-heat for thickness.  If it was me, I would PWHT [for process] to greatly reduce the chance of Stress-Corrosion Cracking.  Failures due to cracking tend to be catastrophic, so I always PWHT.  It's a Risk vs. Cost vs. Consequences thing.  

With the good preheat and interpass temperature you intend to maintain, the Risk is low [but not nil].  The PWHT cost is moderate, especially spread out over the useful life of the pipe.  The Consequences are $1MM and up, since they include the posibility maiming and/or death of an Operator.

Too much 'exposure' when all the factors are weighed togather, IMHO.

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