Shielding Gas Problem.

Date 03-15-2005 05:03

The flux cored wire with -1 designation can be used also with CO2 shielding as the flux contains a little higher amount of deoxidisers, silicon in most cases, which makes it possible to react with and take away oxygen from the weld metal formed by the minor disassociation of CO2 in the arc.

However, 75/25 or 80/20 gas mixtures may also be used with these fillers without sacrificing any mechanical property. Although in carbon steels, impact properties are a little less with argon/co2 mix than with straight co2. We have done it several times for pipelines as per API 1104. In fact the arc is better with mixed gas and the bead finish is also better.

By gsi

Date 03-15-2005 10:19

Thanks for the advice

By - Date 03-18-2005 14:46

A 308LT1-1 and a 308LT1-4 are dual classified. Refer to ANSI/AWS A5.22-95. The -1 only shows that FCW was tested with a CO2 shielding and the -4 was tested with a 75-80%Ar/remainder CO2. One thing to keep in mind is that when using a straight CO2 gas, you will have a lesser acceptable weld bead appearance, you might encounter some spatter, and very possible to pick up unwanted amounts of carbon in the weld. If you are welding on a "low carbon" grade of stainless, there is a chance of putting the weld bead out of the "low carbon" ranges due to the carbon pick up from the gas. Using either gas will still allow you to meet the minimum tensile requirements of 75K.

By jfolk

Date 03-18-2005 18:02

Gsi,

Per ASME IX QW-408 (a), (b), re-qualification of the pqr is required.

John Folk

By - Date 03-18-2005 23:01

Agreed if you change from a argon/CO2 mixture to a straight CO2. But, using a 308LT1-1 with straight CO2 does not require requalification if using a 308LT1-4 using the same gas. I thought the original question regarded only the use of straight CO2. The -1 and -4 designation does not require requalification is using the same shielding gas. QW-408.2 (a), (b), (c) and (d) all apply to the shielding gas only.

By - Date 03-18-2005 23:07

The same applies to using 75/25 for both the -1 and -4 FCAW. No requalification applies using the same gas for either designation.

By ssbn727 (*****)

Date 03-19-2005 10:30

Hi CMeadows!

I think you need to re-read the original post...

Respectfully,

SSBN727
Run Silent... Run Deep!!!

By - Date 03-19-2005 14:18

Good Morning,
Maybe I'm missing something here. It's happened before. <smile> I'm saying that if the author used CO2 as his shielding, he can use either the -1 or -4 FCW designation. The classification test for the -1 designation was done using straight CO2, while the classification test for the -4 was done using 75-80%Ar/remainder CO2. If his tests were done using a -1 FCW and CO2 as his shielding, he does not have to requalify if he uses the same CO2 and starts using a -4 FCW designation. I base my opinion on ANSI/AWS A5.22-95, Table 2, Note (c), and also Table 3 that lists E308LTX-1 and 308LTX-4 as Dual Classified Electrodes. In Sec. IX, QW255, (QW-404, Filler Metals) the change from a -1 to a -4 is not an essential variable. Unless I'm mistaken, which is very likely, the only time a requalification is required is if he changes from one gas shielding (CO2) to an Ar/CO2 mixture.

By Bill Mc (**)

Date 03-24-2005 18:26

So simply stated-
If it your intention to now weld with 100% CO2 you have to requalify a procedure-
If you want to continue to weld with the 75/25 gas you do not have to do anything

By - Date 03-24-2005 18:59

If you are using 75/25 shielding, you can use a -1 or a -4 FCW. If you switch to straight CO2, you have to requalify. Yes Sir, I agree.
I thought the post thought that because he used a 75/25 with a -1 designation, that he was obligated to use CO2. The -1 or -4 only designates the medium used for classification tests at the factory. Either the -1 or -4 can be used with either gas, but if you switch from what you are currently using (75/25) to another (CO2) one must requalify.

CM