Abstract: A valve sub-assembly as illustrated by the drawing insertable at a "T" connection in a preformed channel so as to form a multiport valve at the site. The valve subassembly is characterized by a cage structure containing spaced apart tied together wafers with valve seats and sealing elements thereon, and a shuttle with valve face ends thereon caged between the wafers, the shuttle riding from one wafer to the other wafer. The channel wall portion sealed between wafers is converted into a valve body.The valve sub-assembly includes a face plate attached to the cage structure and spaced apart from the cage structure, so as to site the cage structure in the preformed channel at the "T" connection, the face plate being adapted to seal the channel opening to an outside wall through which the valve sub-assembly is inserted.