Patent ID: 6843509

Claim:
A coupler for joining an aluminum conduit to a steel or stainless steel conduit, comprising: a substantially ring shaped first aluminum layer which has a first hardness and which further has a beveled substantially circumscribing peripheral edge, a first thickness dimension, and a second wall thickness dimension; a substantially ring shaped second layer of aluminum which has a second hardness that is less than the first hardness, and which further has a second wall thickness dimension which is substantially equal to the second wall thickness dimension of the first layer of aluminum, and a first thickness dimension which is less than the first thickness dimension of the first layer of aluminum; a substantially ring shaped third layer of titanium juxtaposed relative to the second layer of aluminum and which has a second wall thickness dimension which is substantially equal to the second wall thickness dimension of the second layer of aluminum, and a first thickness dimension which is less than the first thickness dimension of the second layer of aluminum; and a substantially ring shaped fourth layer of steel or an iron-chromium alloy juxtaposed relative to the third layer of titanium, and which has a second wall thickness dimension which is substantially equal to the second wall thickness dimension of the third titanium layer, and a first thickness dimension which is substantially equal to the first thickness dimension of the first aluminum layer, and wherein the fourth layer of steel or iron-chromium alloy has a beveled, substantially circumscribing and outwardly facing peripheral edge, and wherein the respective layers are explosively welded together to form a ring shaped main body which has a throat having a dimension which extends between the beveled substantially circumscribing peripheral edges of the first and fourth layers, and wherein the respective aluminum and steel or stainless steel conduits each have a wall thickness, and wherein the dimension of the throat is at least equal to the wall thickness dimension of one of the aluminum or steel or stainless steel conduits, and wherein the aluminum conduit is welded to the peripheral edge of the first aluminum layer, and the steel or stainless steel conduit is welded to the peripheral edge of the fourth steel or iron-chromium alloy layer.