Strip weld cladding is a widely used and accepted technique for applying CRAs to the surfaces of pressure vessels and other components operating in aggressive environments. Increasingly the specification requirement has called for products and welding procedures to be designed for single-layer cladding, to reduce both consumable costs and shop welding time.

Most single-layer welding is currently carried out using the electroslag (RES or ESW) strip cladding process, and Mixalloy’s flexible strip production process is ideally suited to the production of strips, such as 317L, 825 and duplex alloys, which are deliberately tailored for use with RES welding. The already impressive productivity performance of RES cladding can be further enhanced by the application of extended stick-out (ESO) technology to strip welding, and this paper describes the equipment and typical welding parameters required to deposit 625-type CRA in a single-layer.

RES welding is, however, still not considered to be universally acceptable, forcing fabricators in certain instances to use the more traditional Submerged Arc (SA) strip cladding procedure. In pressure vessels, SA welding normally requires two or more layers from two stainless steel electrodes, involving a higher alloy buffer layer strip and possibly different flux alloying/ compensation characteristics for each layer. Recent work has shown that the application of ESO technology can make it possible to achieve consistent single-layer welds in traditional CRAs such as 316L and 347, by using the SA welding process with specially formulated strip compositions and non-alloying fluxes. This paper shows how ESO can be used both to improve productivity and to control dilution levels using the SA process.

Finally, the paper describes a novel welding technique which has the potential to expand the use of high productivity single-layer strip welding into applications which suffer from restricted access, such as pipes and nozzles.