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Welding/Dual shield welding


I have to weld a 1/2 steel plate to one another it has a single V groove. I am using .045 wire with 75/25. The steel is 20 foot long 8 foot wide. I have 2 questions
1. Should this be welded in one pass or should it be done in multiple passes.
2. What would be the best way to help with the warping of the steel.
Thank you Sir

0.045" Dual-Shield is a good choice.
If you are planning on seam welding two 8'x20'sheets along the 20' edge then you will have
to take some time to install strong backs or stiffeners to help reduce the heat distortion
caused by weld contraction.

1. Preheat as much of the steel as possible to above 500 degF.
  Heating can be accomplished using propane weed burners.
  When a drop of motor oil smokes on the steel you are around 500 degF
2. Tack weld every 12 inches along the seam.
3. Install stiffener bars every 18 inches. These can be strips of 1/2" steel 4" wide by 4' long.
  These are tacked across the joint, on edge. Remember to only tack on one side of the bar so
  it can be removed easily with a large wrench or a length of pipe with a slot in the end.
4. Run this in 3 passes.
  A. Root pass is run small, hot and fast.
  B. Middle pass is slower with a little weave to it.
  C. Cover pass is a little quicker, but with a wider weave.
5. Allow the weld to cool as slow as possible by either slowly reducing the amount of heat
  added, or burying with sand or wood ash.

If you want to get really nuts about this you can do skip stitching or reverse skip-stitching.

Imagine marking the seam off with a number every foot.
1  2  3  4  5  6  7  8  9 ...

Skip-stitching means welding from 1 to 2, then 3 to 4, 5 to 6, 7 to 8 and so on.
Then come back an weld 2 to 3, 4 to 5, 6 to 7 and so on.
This reduces distortion by breaking up the welding heat.

Reverse skip-stitching breaks up the heat even better.
Start welding from 2 to 1, then 4 to 3, 6 to 5, 8 to 7 and so on.
Then come back and weld 3 to 2, 5 to 4, 7 to 6 and so on.

You get the idea. Skip stitching is primarily used for welding continuous seams on ship hulls,
both aluminum and steel.


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Ernie Leimkuhler


Questions about Oxy-Acetylene welding/cutting, MIG, TIG, Flux-core, Stick welding, brazing and soldering, bike frames, air frames, motorcycle frames, structural welding. Also questions about Welding Certifications and Inspections. All questions about fabrication of metals (stainless steel, steel , aluminum, brass, bronze, copper). Basic questions about underwater welding. TIG is my strongest subject.


Extensive background in most welding fields. 18 years fabrication of metal theatre scenery, 16 years structural steel, 2 years pipe welding, 9 years as a Welding Instructor at South Seattle Community College, and 5.5 years as a Welding Instructor at the Divers Institute of Technology. 16 years Industrial Welding Consultant for fabrication shops in the greater Seattle Area. 11 years Architectural Metal Fabrication. 8 years in Film/TV; SPFX/construction/set-deco/props/. 33 years Blacksmithing and Knifemaking. Currently a Field Welding Inspector for Otto Rosenau and Associates.

American Welding Society - Certified Welding Inspector Washington Assoc of Building Officials (WABO) - Special Inspector - Structural and Reinforcing Steel.

Do a search on google groups for "Ernie Leimkuhler" in the rec.crafts.metalworking and sci.engr.joining.welding groups. Blacksmith's Gazzette - Anvil Making

BA Theatre Technology - Purdue University.

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