A valve arrangement having an insert assembly (11) receivable in a receptacle (10). The insert assembly includes valve elements for controlling fluid flow through the valve. These include a gate (40) and chamber valve seat members (52, 53). The insert is constructed so that it can be removed from and located in the receptacle. When located in the receptacle and in operation the gate is urged against one of the seat members so that a seal is formed between the seat and gate and between the seat and receptacle body. The gate (40) can be an expandable gate. <IMAGE>
