1. Applicable Fields of Ball Valves
seat gaskets are made of rubber, nylon and polytetrafluoroethylene(PTFE), so their operating temperature is limited by the valve seat sealing material. The stop function of the ball valve is realized by the mutual compaction of the metal ball between the plastic valve seats under the effect of mediums. Plastoelastic deformation will happen on partial valve seat gasket due to a certain contact pressure. This deformation can make up for manufacturing accuracy and surface roughness of the ball, and ensure the sealing performance of the ball valve
Because the ball valve seat gasket is usually made of plastic, we need to consider fire-resistant and fire-proof properties of ball valves when it comes to the valve structure and performance, especially in petroleum, chemical and metallurgical departments; we should pay more attention to fire resistance for using ball valves in equipment which contains flammable and explosive mediums and piping systems.
It is recommended to use ball valves in piping systems of two-position control, strict sealing performance, mud, wear, necking channel, quickly opening and closing, high pressure cut off, low noise, cavitation and gasification, little leakage to atmosphere, small operating torque and fluid resistance.
Ball valves can also be applied to piping systems of lightweight construction, low pressure cut off and corrosive mediums.
Ball valves can be used for low temperature (cryogenic) devices and piping systems.
In oxygen pipeline system of metallurgical industry, we can only use ball valves with rigorous degreasing treatment.
When the main oil and gas pipelines are buried underground, it is necessary to use full bore welded ball valves.
When regulatory performance is required, V-notch ball valves with special structure should be selected.
We can use ball valves with metal to metal seal in oil, petrochemical, chemical, power and urban constructions and pipeline systems of 200 ℃ working temperature as well.
2. Applicable Principles of Ball Valves
We choose ball valves with full bore and full welded for the main transmission pipeline of oil and natural gas which needs to be cleaned and buried underground.
For main delivery line buried on the ground, we use ball valves with either full bore and full welded or flanged connection.
As for branch pipe, we choose flanged-connected or welded-connected ball valve with full bore or reducer.
About transmission pipes and storage facilities of product oil, we use ball valves with flanged connection.
As for coal gas and natural gas pipelines, we utilize floating ball valve
s with flanged or internal threaded connection.
In metallurgical oxygen pipeline system, we should use trunnion ball valves with strict degreasing treatment and flanged connection.
For low temperature medium pipe system and device, it's better to select ball valves with bonnets.
We can choose lift rod type ball valves for FCCU(fluid catalysis and cracking unit) of oil refining device.
For chemical engineering piping system, we had better use all austenitic stainless steel ball valves with PTFE valve seat gaskets
For pipelines or devices of metallurgy, power, petrochemistry and urban heat supply with high temperature medium, we can use ball valves with metal to metal seal.
Worm gear operated, pneumatic or electric V-notch ball valves are good for flow regulation.