Needle Valve Test method for
Needle valve test method
A) increase valve inlet pressure to valve opening, observe and record the valve's integral pressure and other requirements or related valve characteristic values. Continue to raise valve inlet pressure to valve discharge, observe valve action, record emission pressure and open height. Then gradually reduce the inlet pressure until the valve is closed, and observe the action of the needle valve and record the pressure. Repeat the test so that the action characteristics of the valve can be determined.
Conditions such as ambient temperature, valve temperature, medium condition, back pressure and installation conditions should be close to the normal operating conditions under pressure release. Sealing surface leakage test shall be conducted according to requirements.
B) experiments with other stressors
The installation of pilot pressure relief valve may not be expected to increase system pressure to exceed normal operating pressure. At this time, it is recommended to use a field test accessory to determine the whole pressure. See figure 2-12 for the typical layout of the site test attachment. The selection principle of needle type valve mainly has a few points
1. In the piping system and installation of low temperature medium, the low-temperature needle valve with the bonnet should be selected.
2. The pipe system of catalytic cracking unit of oil refining unit can be used to select the lifting rod type needle valve.
3. In the equipment and piping system of corrosive media such as acid and alkali of chemical system, the all-stainless steel needle valve of austenitic stainless steel and ptfe is suitable for seat sealing ring.
Metal seal needle valves can be used in metallurgical systems, power systems, petrochemical installations, and piping systems or installations of high temperature media in heating systems in cities.
5. When the flow adjustment is required, the adjustable needle valve with v-shaped opening of worm gear, pneumatic or electric can be used. 6. The pipeline of oil and natural gas, which needs to be cleaned up and buried in the ground, shall be used for needle valves with full diameter and all-welded structure; A ball valve that is buried on the ground, with a full diameter welded connection or flange connection.
7. Pipeline and storage equipment for oil products, and needle valves connected with flanges.
8. On the road of urban gas and natural gas, the needle valve with flange connection and internal thread connection is selected.
9. In the system of oxygen piping in metallurgical system, it is appropriate to choose the needle valve which is strictly degreased and connected with flanged flange.
