Submerged arc welding process

Pipe shall be made by longitudinally welding cold, preformed plate by the submerged arc welding process, using at least one pass from the inside and at least one pass from the outside, single seam. 

All continuous box corner welds were completed from the exterior of the box section using the submerged arc welding process complete with preheat. No problems with twisting were encountered. 

Figure 3 (submerged arc welded AISI 304 plate) and Figure 4 (P-Al Mg 4,4 UNI 5452 MIG welded plate), both belonging to new vessels, show the presence of porosity (gas bubbles) imputable to a discontinuous welding speed and to high values of process electrical parameters.

A submerged-arc process is commonly used for welding stainless steels and carbon steels when an automatic operation is acceptable. The electrode is a continuous roll of wire fed at an automatically controlled rate. The arc is submerged in a granulated flux which serves the same purpose as the coating on the rods in the shielded-arc process. The appearance and quality of the submerged-arc weld is better than that obtained by an ordinary shielded-arc manual process however, the automatic process is limited in its applications to main seams or similar long-run operations. 

Backerud L. Edvardsson T., Influence of process variables during submerged arc welding on the primary structure, Scand. J. Metallurgy, 4 (1975) 267-272... 

In submerged arc-welding, the strip electrode is fed from a coil into the flux bed and fused in the arc. The width of the weld deposit corresponds approximately to the width of the electrode, and mixing with the substrate depends on the process parameters. The procedure is preferably used to clad stainless steels. Because of bum-off and mixing, the electrode must be overalloyed to compensate for the loss of important elements. 

While other methods of reparing machine parts, such as electroslag and submerged-arc welding, have become popular, the thermite process has remained competitive because it requires no capital investment and is easily performed as a one-at-a-time operation. Normally, a certain amount of preheating is desirable, but recently a Self-Preheat process has dispensed with this. ... 

Most nickel alloys can be fusion welded using gas-shielded processes such as TIG or MIG. Of the flux processes, MMA is frequently used, but the submerged arc welding (SAW) process is restricted to solid solution alloys (Nickel 200, Inconel alloy 600 series, and Monel alloy 400 series) and is less widely used. Solid solution alloys are normally welded in the annealed condition, and precipitation hardened alloys, in the solution treated condition. Preheating is not necessary imless there is a risk of porosity from moisture condensation. It is recommended that material containing residual stresses be solution treated before welding to relieve the stresses. ... 

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