Sub Arc Welding of X52 Steel

[Guest102023]

Two-pass (one per side) weld seam on 1/2 inch thick long seam in grade X52 pipe. Requires 40 ft-lb @ -40°F Charpy toughness as-welded.

The Lincoln P223 flux used is neutral and (somewhat) basic, but what wire would fit the bill?

I could specify a wire and flux easily myself but need to settle a dispute.

 

[SJones]

L-61 seems to fit OK.


Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[metengr]

I would prefer using Bohler welding consumables -

EMS 2 wire with their BB24 flux.

If you need to use Lincoln welding consumables, I would agree with the L-61 (EM12K) solid wire. The Lincoln SAW brochure lists the P223 flux with L-61 wire in the as-welded condition as meeting 93 ft-lbs at -40 deg C.

 

[Guest102023]

I like that suggestion, given that the fabricator is committed to Lincoln. (I have never understood how so many seem to be under Lincoln's thrall, other than the possibility that purchasers do consumable selection.) In the past I have gotten a lot of mileage out of EM12K as a general-purpose wire, only changing the flux according to the application.

Metengr, agree and I prefer European products for critical applications; Oerlikon is my personal favourite. But I've been out of the game for a while so I'm not sure who owns who these days.

Now what about -50°F? Seems a low alloy filler might be necessary.

 

[metengr]

Now what about -50°F? Seems a low alloy filler might be necessary.

I don't believe so, you should be able to make 40 ft-lbs . Run a qualification with impact testing at -50 deg F and you will have your answer.

 

[Guest102023]

I know the P223/L-61 combo would do it, based on the published numbers at -40°F, but that one not certified any lower.

The problem is P223/L-56 (EH11K). It is certified to -60°F, but the fabricator is getting poor weld metal impacts even above -40°F. And personally, I don't like that much Si and Mn in a wire.

 

[Guest102023]

Update (eureka!) - one side of the joint was done using a ½Mo wire - this is giving the very poor toughness. The L-56 wire is rated for -60°F, better than EM12K actually.

 

[Guest102023]

What this means is that the PQR designer is 'averaging' on essential variables: two different wire/flux strength levels, and two different wire/flux toughness levels. I don't approve of this practice, but I would like to know from metengr what discussions have taken place at the Code committee level concerning this practice, or if there is an interpretation that addresses it. It could be deliberate or not.

The same situation comes up all the time when qualifying on pipe using GTAW and SMAW filler, for example. On wall thickness less than ~1/2" it is unavoidable to separate the tensile and toughness properties of the two zones (not to mention remelting of some of the first zone). This is a fairly innocuous issue on a simple carbon steel procedure, but when impacts are involved, poor toughness in one of the zones can be masked. It would be legal to generate a WPS based on only the low toughness process or filler metal.

 

[metengr]

brimstoner;
From what I know of ASME Section IX there is nothing that prohibits a contractor to qualify a groove weld procedure with impact testing using multiple filler wires and flux combinations provided the PQR has all of the necessary essential and supplementary essential welding variables addressed. In other words, flux and wire variables are well documented along with deposit thickness.

 

[metengr]

One other bit of information before I hit the send button was this - weld metal deposited under each set of variables must be included in the tension, bend and impact tests -see QW-200.2

 

[Guest102023]

QW-200.2(b) is the pertinent paragraph. I know it is legal, but you can see where there is scope for mischief for a person who is either ignorant or metallurgically creative.

p.s., if I had always strictly applied this stipulation: 'All variables, if recorded, shall be the actual variables (including ranges) used during the welding of the test coupon' then very few WPSs would have successfully crossed my desk over the years.