Question: Do you have any prequalified welding procedures for structural steel? We are using E7014 and E7024 welding electrodes.
Answer: Since you mentioned structural steel and prequalified welding procedures, I assume you are doing work to AWS D1.1 Structural Welding Code --Steel. This standard makes the Contractor responsible for WPSs, including the preparation of prequalified WPSs (D1.1, Section 3.6). Accordingly, I cannot supply you with such WPSs.

If you do not have a copy of AWS D1.1-2004, I strongly encourage you to purchase one.

Your inquiry does not include enough information to address this issue with certainty. But a prequalified WPS could possibly be written with E7014 and E7024, the two SMAW electrodes you listed.

SMAW is a prequalified process (D1.1, paragraph 3.2.1), and these electrodes are listed in Table 3.1 for Group I steels. However, neither electrode is listed for Group II steels. If your application involves those steels, a prequalified WPS is not possible. These SMAW electrodes do not have the low hydrogen coatings required for Group II steels.

In addition to complying with Table 3.1, all the other applicable provisions of Section 3 apply. These include, but are not limited to, minimum preheat and interpass temperatures ( Table 3.2), procedural restrictions (Table 3.7), and joint details (Figures 3.3 and 3.4 for groove welds).

Finally, these requirements must be summarized in a written WPS. Sample forms are included in Annex E, although any format may be used.

Question: I plan on TIG welding anodized 6061 T6 pipe for a saltwater marine application. I was told that if I fail to remove the anodizing I won't achieve a good weld. Yet the commercial welds I have seen do not appear to be sanded or wire brushed. What does this application require?
Answer: When it comes to welding anodized aluminum, there are two solutions — what you should do, and what the guys who build tuna towers do.

In most cases, the best method remains sanding off the anodized coating in the weld area and making the weld using conventional techniques. You are correct — not removing the anodized layer results in porous and generally poor-quality welds.

A technique has been developed by the boat tower industry that seems to work well for this application. It involves setting the welding current on the TIG machine quite high — around 200 to 275 amps, depending on the thickness of material. The operator uses a remote output control, typically a foot pedal, to obtain full current for 1 to 2 sec — just long enough to form a puddle and add a dab of filler.

The arc is then turned off at the torch, and the torch is advanced half the puddle's diameter. Then the puddle is allowed to solidify.

The high current portion of the weld cycle is reinitiated starting the next weld cycle. This cycle is repeated over and over at 1 to 2 sec intervals. This seems to work well although it takes a practice to become competent with the technique.

This column is sponsored by Penton and the Lincoln Electric Co, Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 yr. Send your questions for Mr. Barton in care of WDF by e-mail to: askdav@penton.com