Welding Procedures

[Merzi]

I am Qualifying a welding procedure for Low temperature service with impact. senario is as follows

a) If I qualify pipe to pipe with SA 333 Gr 1 or 6 which
falls under P1 G1 category, I can weld on SA 516 Gr55,60
& 65, Sa 350 LF1, 420WPL6. But I cannot weld SA 516 Gr
70 and SA 350 LF2 as they fall under P1 G2.

My question is if I wand to weld SA 333 Gr 6 pipe to SA 350
LF2 flange how should I qualify.

Merzi

 

[metengr]

Are you working to a particular ANSI/ASME piping standard - like B31.3 for this job?

You need a qualify a welding procedure specification (WPS) with impact (notch toughness) testing for P-No 1 Group 1 to P No-1 Group 2 materials in accordance with the impact testing requirements of the applicable piping standard.

For the WPS qualification, follow the supplementary essential welding variables listed under the particular welding process(es) you intend to use, as described in ASME Boiler and pressure Vessel Code, Section IX, Article II QW-251.2 and QW-252 thru 265.

 

[weldtek]

Another little trick to keep in mind is to use dual certified material. With a little effort you can find a piece of material certified as SA516-60 / 70. This allows you to qualify the procedure with one set of impacts for the weld and one set for the HAZ. Also, remember that for any qualified procedure you may already have, that is not impact tested, per Sec IX, you may weld a coupon folowing all of the essential and suplementary essential variables, and perform impact tests only. The beauty of this is that you are able qualify a wider range of material thicknesses with a little less effort, and cost.

 

[Merzi]

this procedure will be used during the fabrication of Heat Exchangers.

Weldtech is talking about using dual grade materials, which I am aware of. But in this case I have a 2" Sch XH pipe (wall thk .281) welded to SA 350 LF2 flange. If I qualify on a Dual grade plate the thk available is only 1/4" with range from 1/4" to .5".

Merzi

 

[weldtek]

That's why I suggested using an existing non-impact tested procedure, if one were available. The ideal scenario being something like, qualify a procedure on 1.5" thick plate with bends and tensiles, let's say using the SMAW process. Now qualify a thinner plate, say 3/16", using the same essential and supplementary essential variables, and perform impact tests only. Your qualified thickness range is 3/16" - 8". If you used 3/16" thick dual certified material you have added a group # with no extra cost.
Bear in mind that heat input is limited to that used on the test plate, so you have to think it through and plan your attack.

 

[metengr]

Review ASME Section VIII, Div 1 notch toughness testing requirements. Your welding procedure would be qualified per the impact test requirements in UCS-65 Low Temperature Operation.

 

[weldtek]

metengr,
I'm not sure if I'm missing something. My suggestions are referencing Sec IX requirements.