The EN Series Needle Valve design of Alco Mono-Flange is widely used on isolation and vent applications. Vent being single isolation 10mm (3/8”) bore needle valve.
Integral studs (though bolting) are fitted to each valve allowing the outlet to be blanked off using a blind flange (flange x flange configuration). The flange is therefore removable without loosening of the valve from the vessel or line to which it is attached.
All studding is permanently fixed using a 4mm(3/16”) dowel type locking pin to prevent the studs from moving during assembly or removal of the Mono-flange valve or the flanges. The valve is designed in accordance with the SHELL specification 77/162. Several other end user oil companies use derivatives of this design which can have ½” NPT female outlet which removes the need for the integral bolting.