From 1969 through the mid-1970s, Clack participated in a joint venture in Belgium with Erie Controls, with Clack responsible for manufacturing Apex-style mineral tanks. Because of the 1974 oil crisis, Clack began manufacturing blow-molded brine tanks by 1975. Clack Corporation later formed a joint venture in Belgium with Structural Fibers, distributing Clack products as well as manufacturing Structural FRP tanks.