Proper Welding Method

Don't you have a welding specification?

Dear Mr. Ahmadbilal

Good Morning,

You can carry out the welding by making single V edge preparation with proper root gap up to 2mm and root face up to 1-2mm and root run welding by SMAW/GMAW after that you may go for SAW welding.

or by making root face 2mm with out root gap directly you can go for SAW welding process.

for all process please select proper welding consumable like welding electrode,welding flux,gas and filler wire etc. with trained/experienced welding operator.

First you qualify WPS/PQR/WPQ and welding operator.

Anil

I worked as a welder for five years, and went to school for two years and learned a lot about welding procedures from both. The one thing I learned about selecting a process and filler material for welding specific materials is that WELDING SUPPLIERS often know best about what kind of filler material and process to use.

Based on your application, at 800 PSI, you need to make sure a welding professional with a lot of pipe experience performs the procedure. 10mm thickness warrants either a FCAW or SMAW welding process. Those would be the two most economical options. SMAW is an old process, but is still used for field welding to AWS specifications in many places. Contact a supplier of welding filler material, give them the chemical makeup and TENSILE STRENGTH of your material, and see what advice they have for you.

I would personally recommend a FCAW multi-pass procedure...it is clean, you can get a very specific filler material for it, and it penetrates well. You must also consider, based on chemical makeup and tensile strength, whether you need to preheat the weld zone on your project. Clean joints, proper weld-preparations, and proper techniques are vital. Being that this is a common API line-pipe it sounds like it isn't a very high-alloy content steel...but I could be wrong.

In my view, the best method for 6.0 mt length 10 mm thick pipe welding will SMAW process using E 6010 / E 7010 for root application and E 7018 for Filler and cap passes. But you have not indicated the no of joints to be welded. Take re-backing precautions for your low hydrogen electrode to ensure x-ray quality welds.

At the " T " joint junction, make sure that, proper grinding is done, ends bit tapperd off on either side of log seams to get full fusion and penetration during circumferential welding.. Otherwise you may land in LF /LP (or) longitudinal hair-line cracks at times.

No pre heating is required since it is only 10 thick.

Alternatively, you can try E XXX0 / EXXX3 electrode for root and ER 70 S-6 ( GMAW Process) size 0.80 mm for balance passes. Use Argon (or) Argon + CO2 mixture gas to avoid pores during welding and Dip / short circuit transfer mode. FCAW can not be used successfully at lower end parameters for 10 thick material.

You can also substitute E XXX0 with E XXX3 electrode for root pass and either of above procedures for balance passes.

In all the cases, you have to do WPS, PQR and qualify your welder(s) prior to actual welding. If you have any PQR done earlier for above you just follow it forgetting all above..

Sridhar.

This looks to be about the same configuration of pipe that a welder must make to qualify a "multiple qualification test" to API 1104. It appears that the writer is referring to the seam weld in the pipe when he says "longitudnal" welds are involved.

I agree that the weld should be made with SMAW if the job is to be performed outside. For this type of weld in the pipeline industry, an E6010 or E7010 electrode is more often used for the root bead, hot pass and cover. The root bead (stringer in pipeline language) is usually put in with a 1/8" diameter electrode and then a larger electrode (5/32" or 3/16") is utilized for the hot pass and cover.

The welds are generally made in the vertical down hill position.

After you decide the welding methods you need to obtain a Welding Procedure Specification (WPS), qualify it and generate a Welding Procedure Qualification (PQR) and then do a Welder Qualification Record for each welder welding operator for each process you intend to use on this project. From the material and pressure information this is some serious pipe you intend to build and there are alot of things besides welding that should be considered here.

On the longitudinal seam a SAW welding head on a track that could travel the length of the pipe with the single V grove groove design. First I would weld the pipe longitudinally and do the weld inspection, NDT and pressure test required to ensure the weld/pipe meets your requirements. Before you inspect/test the pipe you will have to make repairs to the weld ends in place as well as any repairs found by the inspection/NDT. This can be done with many different types of manual welding but I would suggest FCAW or SMAW process to make these repairs.

If you plan on doing all the welds in the shop and you have welds in a tee intersection where 2 seams meet I would make these manual welds with the same manual process that you use on the end of pipe repairs.

On the circumferential seams welded in the shop I would use 2 or 3 pipe roller positioners to roll the pipe and a stationary head SAW or FCAW welding process utilizing the proper single V grove to make the welds.

In the field I would personally use a GTAW/SMAW duel process welding procedure on the circumferential seams which would require GTAW root and Hot Pass and then SMAW to finish filling the welds out and cap