A plug valve whose chamber or bore and whose runs or port passages are fully lined with corrosion-resistant material, most preferably polytetrafluoroethylene, such valve having recesses in its runs, Plug Valves near their intersection with the bore, into which lining material distended by heat and pressure may creep, and with the valve body defining an internally rounded concave wall or dome at the bottom of the bore. The lining material is formed within the runs so as to be under tension longitudinally between the bore and the outer ends of the runs,Water Pump Control Valves and the lining material extends integrally upwardly from the bore and outwardly of the valve body to define a thick collar immediately above the neck of the bore. The valve is manufactured by use of an integral hollow rubber or like forming element comprised of tubular legs, and is placed inside the valve body with one such tubular leg extending through each run and through the bore. Different components of a multi-part mandrel are then inserted inside the tubular legs of the forming element and assembled together therewithin.FORGED STEEL VALVES Following this, the space between the rubber forming element and the inner walls of the valve body are filled with lining material, which is then compacted by resilient outer expansion of the forming element. Subsequently, the valve body and the compacted lining material are heated to coalesce or cure the latter in place.  In a lined plug valve, of the type having a one-piece valve body with walls defining a generally cylindrical chamber for receiving a plug-like valve member which is rotatable within such chamber to open and close a flow path through the latter and defining an opening in axial alignment with said chamber which extends laterally through the walls of the valve body and communicates with an end of said chamber, the improvement comprising: liner means covering at least a major portion of said chamber; said liner means being a one-piece member of PTFE formed in place within said chamber and having an integral, generally tubular portion lining said opening and extending through and beyond said opening generally parallel to the axis of said chamber; a plug-type valving member disposed within said chamber; said valving member having an upper portion extending through and beyond the said valve body opening aligned with said chamber; and said generally tubular portion of said liner means which extends through and beyond said opening having a part which encircles and contacts said upper portion of said valving member along a predetermined axial length of such portion whereby a seal is formed around at least part of said upper portion of said valving member.

MORE NEWS