- December 16, 2022
- Posted by: admin
- Category: Safety Valve Testing
Safety Valve Testing: The smooth and safe operation of any industrial process depends on valves that function with precision. Valve testing makes sure that the valves are good enough to meet design standards and specifications within their operational life. Valve testing makes sure that they are fit for service. However, testing is also performed at regular intervals post-installation as a part of the standard practice. The valves are also tested for EMC compliance.
Today we will have a look at commonly used types of valve testing and guidelines for valve testing. There are different types of testing for the valve and the best testing safety valves is determined on the basis of application, manufacturer standards, as well as specifications mentioned by the customers.
Here’s a look at some common Safety Valve testing procedures:
General Pressure Testing
In this type of testing the valve is filled with a liquid. Usually, it is water with a corrosion inhibitor. Pressure is applied for a specific period of time wherein the level of pressure and duration varies based on valve material, category of pressure test, and size of the valve. The pressure is more than the usual working pressure of the valve. It aims to examine the integrity of the valve shell, seal, and seat against leakages because of pressure.
Hydrostatic vs Pneumatic Pressure Testing
Though water is one of the most common mediums for valve testing, some conditions require pneumatic pressure testing of the valves. In this type of testing, air/ inert gas like nitrogen is used. Hydrostatic testing is suitable for applications where equipment is not sensitive to moisture. Pneumatic testing is advised where moisture can damage some equipment due to corrosion.
As per industry guidelines, pneumatic testing is recommended for low-temperature or cryogenic valves.
The valve shell is the main body of the device. The testing is based on the guidelines from API 598 and ASME B16.34. The valve is placed on a test bench and kept partially open. The shell is then pressurized with ASME B16.34 with 1.5 times the allowed valve testing pressure at 100-degree F for hydrostatic testing. In Pneumatic testing, it is 1.1 times the optimum allowable pressure. ASME and API standards suggest different durations for testing based on the size of the valve being tested.
Usually, the valve seat testing is conducted after the valve shell testing. Furthermore, it is done with same API and ASME testing standards as suggested for shell testing. Also, the recommended pressure is 110% of the maximum allowed pressure at 100 degrees F. Finally, the testing times differ based on the size of the valve.
For industrial valves, it is important to have fire protection. It is all the more relevant for refineries, oil & gas, and petrochemical industries. The valves in these industries should also offer assurance of shut-down in case of fire. The valve is pressurized with high-temperature flames from 1382 degrees F to 1832 degrees F for a duration of 30 minutes. The leakages and heat intensity are measured in this duration.
Fugitive Emissions Testing
To begin with, the test aims to evaluate the impact of gas/ vapor leakage from the valve. Then, as per studies, 60% of fugitive emission is from the valves. This data shows the significance of fugitive emission testing. Gases used during the testing are methane and helium wherein they pressurize the valve at different temperatures.
This type of testing is done for valves functional at low temperatures in cryogenic services. The procedure places the valve in an insulated tank with liquid nitrogen at a temperature of – 320 degrees F. The valve temperature and leakages are checked during the testing.
For safe and fully functional valves, it is important to get them tested based on the regulatory requirements.
Contact Trivedi & Associates Tecknical Services (P.) Ltd– the best statutory and compliance company in Gujarat.
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