![]() ![]() exposure of valve closure element to corrosive testing fluids.Corrosion in the valve disc can be caused by the incompatibility of valve material and fluid in the system, and.These measures are essential for the optimal operation of globe valves and increases their service life.īelow are some common globe valve failures and ways of solving them: Globe Valve Failures, Causes, And Solutions Damage By Corrosion Of Valve Disc However, globe valve maintenance practices and preventive measures are cheaper and easier ways of ensuring the valves do not fail. If these problems persist, the failed globe valves may waste good amounts of fluid, which can damage to the system, and lead to costly repair expenses.Įlimination techniques such as repacking the gland, replacement of valve parts, or replacement of the entire valve can be implemented to solve some of these problems. Also, these failures can be caused by wrong valve size and material selection, poor maintenance of valve parts, or frequent use of the globe valves. Globe valve failures usually occur due to leakages in the disc, seat, stuffing box, sticking valve stems, and loose valve discs. Therefore, industrial globe valves must be tested by qualified and trained professionals. Valve inspection and testing methods may differ with different testers. This test visually checks the valve body, stem, bonnet, and closure element to ensure conformance to valve standards. Only a limited amount of leakage is allowed at the seat sealing surface for low-pressure and high-pressure closure tests.Īir, water, inert gas, kerosene, or non-corrosive liquids with equal or less viscosity than water are the test fluids used in high-pressure closure tests, and air or inert gases are used for low-pressure closure tests. But for the DBB high-pressure test, apply fluid pressure successively through both ends and check leakages in the body cavity. These tests include the low-pressure, high-pressure, and double block and bleed (DBB) high-pressure closure tests.įor the high-pressure and low-pressure closure tests, apply fluid pressure through one end of the valve (inlet or outlet) and check leakages through the other end. Closure TestsĬlosure tests check for leakages in the valve’s closure element. While the fluid used in the high-pressure backseat test could be air, water, inert gas, kerosene, or non-corrosive liquids with equal or less viscosity than water, the test fluids used for low-pressure backseat tests can only be air or inert gases. Close the valve disc and check the other end for leakages. Introduce the test fluid through the bottom end of the valve disc and check the packing and gasket for leakages. The backseat tests allow for the replacement of the valve packing while in service.įor this test, open the valve disc and position the stem or shaft vertically. These tests check for leakages from the stem or shaft to the seal. ![]() Backseat Testsīackseat tests include low-pressure and high-pressure backseat tests. Check the valve body and cover for leakages. The pressure applied should be greater than or equal to one-and-half times the maximum working pressure. Open the valve disc and introduce the test fluid into the valve. The fluid used could be air, water, inert gas, kerosene, or non-corrosive liquids with equal or less viscosity than water. The Shell tests are required for valves that operate in fully open or closed services. These pressure tests check the strength and soundness of the valve body. The shell tests include the Shell Test and the High-Pressure Pneumatic Shell Test. The following are the types of standard tests that can be performed on your globe valve: Shell Tests These standards test, inspect and examine globe valves. The standards for globe valve leakages and ratings are provided by the API standard 598. Valve leakage standards specify the maximum allowable leakages for each valve under specific conditions. For hydrostatic tests, the test fluid is liquid which includes water or kerosene, while for pneumatic tests, the test fluid is gas which includes air or nitrogen. Globe valves can be tested for leakages using hydrostatic tests or pneumatic tests. However, the interval for testing should depend on the operational application, the valve condition, and the required valve output. Industrial valve manufacturers recommend that globe valves be tested once every year. Also, to avoid globe valve failures and ensure safe operations, they have to be regularly tested.Ī globe valve buyer may also require a valve test before purchasing to confirm the integrity of the valves. To ensure that globe valves conform to the required API valve standards, they must be tested.
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