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Some welding on ships was attempted in World War I, but its failures impressed engineers more than its successes: no protective coating for the rods had been developed, so the arcs were not gas-shielded, and the welded seams were of inferior metal; the arcs' temperatures were hard to control, and welded plates often heat-warped. Development of the arc-shielding coating by Milwaukee's A. O. Smith Corp. at last gave arc welding the reliability it needed.
In shipbuilding, welding:
> Saves man power hence cost. One welder can assemble as much steel as a four-man riveting team. Since only some 20% of the required skilled labor was on hand when the defense shipbuilding program began, it was four times as efficient to train welders as it would have been to train riveters.
> Saves 13% deadweight in a ship's hull, and proportionally increases the vessel's carrying capacity. Weight reduction comes from elimination of 1) overlap of a ship's plates—welded they lie butt to butt, 2) angle-pieces often required in riveted joints, 3) the rivets themselves.
> Saves time, because large hull sections can be welded together in shops, then hauled & hoisted to the ways and welded into a complete hull. In shops welding is quicker than in the ways, since a welder can easily reach difficult spots and never has to weld over his head with molten steel drops raining down on his mask and shoulders. Formerly, a keel was laid in the ways and riveters started at the middle and worked slowly toward each end of the ship, because the plates had to be staggered and overlapped in an intricate patchwork. The 530,000 rivets in a typical 1918 freighter filled perhaps as many as 1,500,000 rivet holes, whose bothersome drilling can now be eliminated wherever welding is used.
> Saves materials (and further weight) because absence of rivet holes, which weaken sheet steel, means that plates and beams can be cut from thinner steel.
> Saves building many new shipways. Now, when much construction takes place in shops, a typical ship occupies its ways about five months—instead of eight months during World War I.
These amazing, interrelated economies have made welding the greatest bottleneck smasher in U.S. shipbuilding. Welding is being used wherever possible, but some riveting still goes on. Reason: shortage of welders, and the existence of riveting skills and equipment which it is not yet wise to junk. In 1918 some 16% of a ship yard's personnel were riveters. Today the average is about 1%.
Steel-framed buildings. In land construction welding's methods and savings are similar to those in shipbuilding. Welded structural steel is 7 to 10% cheaper than riveted — an economy which guarantees that riveting will never echo again in U.S. cities. Increasingly common in recent years, welded steel frames would have supplanted riveted buildings five or ten years sooner in most cities had not backward building commissions feared that welding was some sort of tinsmith's soldering.