Welding Tips and Tricks

Hi we are refurbishing a semi-trailer and our welder has been working on heavy haul semi-trailers for over 30 years and has always used mig and the company we are doing this trailer for wants us to use .045 flux dual shield for this job.....any pro's con's or suggestions on which way to go.....he is more comfortable with mig and has never had any problems with his welds.... thanks

Welcome aboard, Trailer,

I'll gladly take this question head-on.

I designed a subframe for a Meritor air-ride conversion, for a tanker that weighs 46000 empty. There's a mix of carbon and stainless steels. Members vary from 1/4" SS (the web from the triler doublers) to 1/2" CorTen for the lower frome rail the towers weld to. In between are 3/8" SS gussets outside, and 3/8 SS fabricated channel.

Every inch of this is done in hardwire MIG, with downhand permitted (with 3/8 minimum width). This satisfies the (fortune 500) client's requirements, and my design now has roughly 20 million miles in-service.

An argument can be made for dual-shield, and an argument can be made for uphand mig, but the short answer is, if the man really knows what he's doing, let him do it!

Steve S

I will add to Steve's comments. I am experienced in T1 welding and have a thread in the library for reference material. There is absolutely nothing wrong with hard wire, dual shield or stick electrode welding as long as it meets the strength requirements specified. We used Lincoln .052 LA-90 for our application. We needed around 100ksi strength and this met our requirements just fine. If you have already welded T1you probably already know but will throw it our anyway. Pre and post weld heat treating is a requirement to keep the strength of the T1.
In don't remember off hand which it was but there war a dual shield or metal core that met our specs but we opted for the solid. I would suggest to stick with what is already been proven. Changing wires will require a new PQR and WPS to be written and it is probably not worth the expense, unless this will be a long tern application.
If the company is requesting the switch to dual shield you must request a WPS or wire spec to weld to.
What wire and gas have you been using in the past?
-Jonathan



http://forum.weldingtipsandtricks.com/v ... =19&t=4735

We are using 75% 25% gas and Pinnacle Alloys Premier S6
AWS Class ER70S-6
AWS A5.18 ASME SFA 5.18 ; CWB approved And will be welding 3/16" T-1 web flange to 3/8" T-1 top and bottom flange. and the flux they suggested are as follows
http://www.hobartbrothers.com/uploads/p ... _Arc71.pdf

http://www.lincolnelectric.com/assets/g ... /c3101.pdf


http://www.hobartbrothers.com/uploads/p ... tiCorI.pdf
with a 75/25 gas mix Thanks