The check valve is a shut off device, developed for feedwater piping in high-pressure boilers and pumps. The check valve opens, automatically caused by the flow of the medium and shuts due to the gravity effect of the swing plate causing counter-pressure in case of flow interruption. Because of the glandless fitting of the valve shaft, a trouble-free and simple operation is guaranteed. Furthermore, needing no gland, leakage is quite impossible. The check valve is basically equipped with a self-sealing cover-plate. It is also employed as a safety device to check reverse-flow in pipelines carrying superheated steam and in long distance pipe systems with highest pressure ranges.
with welded ends,
one side with welded ends, and other side with flanges,
one side with welded ends, and other side butt-end or threaded end for cramp socket-connection,
with minimum flow connection upstream of the valve plate and relief nozzle downstream of the valve plate, special requirements are considered.
Design and Function
The check valve casing is manufactured of solid forged steel piece. The wall thickness is designed for maximum pressure rating and temperature up to 650 °C. In order to stop reverse-flow the swing check is mounted in the disc lever with little axial and radial play and held by screw nuts. The disc lever can turn freely round the shaft. The movable parts of the disc are fitted separately from the sealing parts. After tightening, the screw is secured and presses the disc firmly against the four-parted thrust ring thus protecting against slipping. The cylindrical pin prevents a horizontal displacement of the disc. The casing is provided with a self-sealing cover-plate.
This construction guarantees that the valve disc fits firmly even when no pressure is acting, also in a horizontal and vertical piping, whereas in vertical installation it must be made certain that the flow direction is from bottom to top. The welding of the valve and heat treatment of the seams may be carried out without removing the internals. The check valves may be pickled without harming the internals.