I have to write up a "new" weld procedure for a job that is coming up quickly for A333 pipe. It has to have "Impact" testing to -50 degrees F.
I'm looking for any help or hints from the unbelievably knowledgable people in this forum!
The Code used is the ASME B31.3 Process Piping Code.
I'm looking at a pre-heat of 100 degrees F with a maximum interpass temperature of 450 degrees F. We will be using the GTAW process with 100% argon sheilding...no backing gas.
Sounds okay so far?
Filler metal is my big question...I've been told that ER70S-2 may not be adequate to pass the impact requirements and that I should look at ER80S-Ni1 for this procedure.
Anyone had experience in impact testing this material? I've quite a few other weld procedures on many other materials, but never one with impact testing requirements.
I realize the material is pretty much regular carbon steel (P-1 Group-1) but it's the weld metal and HAZ that has me concerned.
Any help would be appreciated!!!
Darren.
SFA-5.28 shows ER80S-Ni1 and ER80C-Ni1 tested in the as welded condition at -50F. If you can lay your hands on an ASME Section II, Part C, look up SFA-5.28, Table 4. The 70 series in SFA-5.18 only test at 0F and -20F.
properly welded weld metal with ER70S-2 should get over 100 ft-lb at
-50F, but the 1% Ni material is more conventional for low temperature applications. As long as you don't get your heat input up high enough to damage the HAZ or degrade the properties of the weld metal, you should be fine.
Not sure...do I reply to myself if I want to post my results??? :)
I ended up running two separate weld procedures because I didn't read Section IX close enough for the minimum thickness qualified.
The first one, we used 6" sch 40s pipe (.280" nom.) A/SA333 Grade 6 using GTAW with a maximum heat input of 38Kj per inch (Seemed very high to me but...) in the 6G position. My HAZ impacts were between a low of 128 and a high of 143 foot pounds at -50 degrees F. My weld metal imacts were between a low of 89 and a high of 143 foot pounds impact. This qualified us for a minimum thickness of .280" and a maximum of 2T.
I then realized that we needed to weld some 3" sch 40s (.216" nom.) so the first procedure obviously didn't cover this so...start again.
This time we used 6" sch 40s pipe, but machined it to .249" in thickness. (This would qualify us for 1/2T minimum and 2T maximum).
This one, we had a bit lower maximum heat input of 28Kj per inch and the impact values were actually quite a bit lower. HAZ low was 73 and high was 109, and the weld metal was a low of 24 then 60 and a high of 96 foot pounds.
I'm not sure why there was such a high range, but they passes and that was the main concern...any ideas???
If I had more time and thought about it more, I should have gotten a piece of A/SA106C and welded it to the A/SA333 Grade 6. That would have qualified us to join P1 Group 1, and P1 Group 2 to themselves or to each other.
Congratulations on the sucessfull test. I'm used to testing thicker material, so we use full size CVN specimens and don't have to worry about the cooling rate too much. With the thin material, the cooling rate can slow down quite a bit. The CVN scatter you observed is very common for low temperature mild steel applications. We experience greater scatter that what you saw at times. Which filler metal did you end up going with? What size CVN specimens did you use, and are the results you posted corrected for the sub-size specimens?
We used the ER70S-2 - 1/8" diameter for both procedures. The specimen size was 10mm x 5mm x 55mm for both procedures. The test report that I received doesn't actually state if the results have been corrwected for sub-size specimens...I better make a quick phone call...
It was a great learning experience for me!!! I've done a lot of other procedures, but never had to deal with notch toughness before.
Just curious why you ran 6G and used pipe materials? You wouldn't have had to unless you were just seeking performance quals at the same time! I use plate in the 1G whenever possible; remember, in most cases position and product shape is not an essential or supplimentary essential variable, keep it simple!!
I did the pipe in the 6G position for two reasons...the first was for the welder performance qualification, and the second was to qualify the impact tested procedure for all positions..."Position" is an supplementary essential variable (QW405.2) so I could have done a 3G plate test to qualify the PQR, but did the pipe out of position to "Kill two birds with one stone".
Hi there, this message goes back a long ways.
For welding with ER80s-Ni1, does this procedure need to have a purge?
I just completed a similar procedure without purge, but it failed the root bends. I did not purge the pipe.
Thanks.
Ni-1 should not need a purge in order to pass PQR bend.
Where did the failure occur? What did it look like?
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