US 5,305,946 A · Welding process for clad metals

Abstract

A weldment, such as the wall of a pressure vessel, is formed from segments, each of which includes a steel substrate, a protective layer of tantalum which is exposed to the interior of the vessel and an intervening layer of copper which lies between and is bonded to the substrate and the protective layer. The substrate and the two layers which form the cladding are explosively bonded together and the bonding procedure may leave the protective layer with small domes or embossments and pockets of trapped gas behind the embossments. The two segments are welded together edge-to-edge at their substrates, with their protective and intervening layers aligned. If one were to follow the traditional procedure, one would place a tantalum batten strip over the protective layers along the opposed edges so as to cover the edges, and then weld the batten strip to the protective layer along the edges of the strip. But any weld which passed over a pocket would open the pocket, causing the trapped gas to burst out and carry molten copper from the intervening layer with it, and of course the copper would contaminate the weld, leaving it less capable of resisting chemical attack. This problem is alleviated by venting the pockets over which the batten strip passes with small holes and driving their embossments down. The batten strip overlies the holes so corrosive substances will not pass through the protective layer.

Claims20

Dependent claims

A process for joining two segments into a weldment, each segment having a substrate formed from one metal and a protective layer which is formed from another metal that is attached to the substrate and includes embossments which cover pockets in which gas is trapped, said process comprising:

welding the two substrates together at edges of the segments such that the protective layers are generally aligned at those edges of the segments;
venting the pockets which are located along the edges of the segments;
placing a batten strip over the protective layers of the two segments such that it projects laterally beyond the edges of both segments and covers the locations where the pockets are vented;
and welding the batten strip along its edges to the protective layer, with the welds so formed being continuous along the edges of the batten strip so as to isolate the edges of the protective layers and the pockets from substances to which the protective layer is exposed.

1 more element

A process for joining two segments into a weldment, with each segment including a steel substrate, a protective layer which is exposed at one surface of the segment and is formed from a metal which resists corrosion, and a metal intervening layer which lies between and is bonded to the substrate and the protective layer to provide a heat sink so that a high temperature concentrated at a small area in the protective layer dissipates in the intervening layer, the protective layer having embossments where it is separated from the intervening layer, with pockets of entrapped gas existing between the protective and intervening layers at the embossments, said process comprising:

arranging the segments edge-to-edge with their respective substrates, protective layers and intervening layers aligned;
with the segments so arranged, welding the segments together at their substrates;
venting the pockets for those embossments that lie adjacent to the opposed edges of the segments;
driving the vented embossments downwardly toward the intervening layer, so that the vented embossments become generally flush with the remainder of protective layers from which they formerly rose;
placing a batten strip, which is formed from the same metal as the protective layers, over the protective layers such that it obscures the opposed edges of the two segments and covers the locations where the vented pockets are vented;
and welding the batten strip to the protective layers along the edges of the batten strip, so that the locations where the vented pockets are vented lie between the two welds along the batten strip.

3 more elements

Dependencies are inferred from the claim text.

Welding process for clad metals

Life of this patent

Welding process for clad metals

Life of this patent

Abstract

Claims20