Tip of the day – 90 degree orientated Gate Valves
July 6th, 2017 by Amanda Schumann
Cast steel API 600/ API 603, mass produced Wedge Gate valves and inline, cast globe valves will not necessarily always function properly on a 90 or 45 degree angle which is common practice in refineries.
Forged Gate & Globe valves up to 50NB always seal properly but don’t install them in a position where the stem is pointing downwards below horizontal as debris can accumulate and effect operation. Click here to view the APV forged IOM.
Cast steel gate & globe valves will operate perfectly in an upright position when the wedge/disc gravity feeds into it’s seating position. However, when the valve is on an angle, sloppiness combined with slight burrs and machining imperfections can cause the valve not to track properly in it’s position every time it is closed. Manufacturers will claim all their valves will close perfectly in any position, however in practice this is often not always the case. If the valve is not being used in a conventional horizontal pipeline, this should be specified at the time of order as it’s best that unless the size/class being used has been proven as reliable, the valve should be function tested to prove it correctly seals in the desired angle in which it will be installed. Depending on the size and class, you will find every now and again, some valves do require disassembly and machining corrections in order to get the valve to reliably close and seal.
In the case of cast iron valves there can be a similar problem although resilient seated gate valves are reliable in vertical lines as are many other styles of industrial knife gate valves, etc.
In the case of swing check valves they can be used in vertical lines but only in upwards flow direction, not downwards (unless a spring is fitted).