In processes with aggressive fluids or critical leak concerns, semi-welded plate and frame heat exchangers are the best choice. Two laser-welded plates form a cassette through which the aggressive fluid flows, and gaskets are used between cassettes.

Semi-welded Plateflow heat exchangers feature a 90% reduction in fluid-gasket contact area compared to regular gasketed plate and frame units. Gaskets are available in standard elastomers or specialty materials, and the cassettes are also available in a range of metals.