The allowable leakage value used in this paper only represents the grade of various universal valves, and should not be used as a standard. The assessment standards for leakage level of control valve seat are generally divided into ANSI I, II, III, IV, V and Class. Each of these levels has its own specific test method and allowable leakage value under its test conditions.
Level VI is the highest leakage level of the control valve, and Level VI is often misunderstood as.; Gas tight;, In fact, Class VI allows a certain amount of leakage, which is usually measured by the number of air bubbles escaping from a specified test tube per minute. Class VI is generally used for elastic seal valves. But it can also be used for valves with other sealing forms, and has been practiced in this regard. The leakage test medium of Class VI valve seat is air or nitrogen at 5O~125 (10~52 ℃). The test pressure is the lower value of the maximum rated pressure of the valve core compared with 50psi (0.35MPa).

Structural characteristics of corrugated compensator:
1) Bellows are "Ω" shaped waves with large flexibility, small rigidity and no stress concentration.
2) Pull rod structure: the screws with nuts on both sides are connected to the tubular nut in the middle, so as to adjust the length of the bellows and limit the expansion of the bellows. Easy to install.
3) The loose flange from one side of DN32-80, especially above DN100, adopts ring less welding structure to prevent cold work hardening. Effectively deal with the problems such as easy to break and leak caused by the brittleness of welded joints of bellows. Extend the service life of bellows.
4) Each bowl shaped lug is equipped with a high-quality shock absorption rubber pad. The PTFE compensator prevents vibration from being transmitted through the pull rod, thus improving the product's performance of absorbing pipe noise and reducing vibration.
5) There are three to four evenly distributed bowl shaped lugs on the flange edge, and they are equipped with pull rods to strengthen the working pressure of the bellows.
Application scope of corrugated compensator: general factory piping and places requiring flexible connection; Import and export of various pumps, valves and air compressors; Various fire piping, air separation piping, steam piping, etc; Domestic water piping and places requiring sanitation; Places where mechanical equipment piping requires vibration reduction and thermal displacement compensation.