Are eccentric butterfly valves single-direction or double-direction?
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In API609, there are Class A and Class B classifications; Class A corresponds to centerline types, while Class B refers to eccentric types. According to the standards, Class B components must undergo a double-seal test. So, does that mean that all eccentric types (Class B) require double sealing? ? It seems that currently, the central liners available on the market are mostly bidirectional, while those that are eccentric are unidirectional – isn’t this the opposite of the standard? ?
Hehe, even the biased ones have double sealing. The double-eccentric high-performance butterfly valves produced by our company can achieve a sealing performance of level 6 in both forward and reverse directions
I know that eccentricity can also be bidirectional, but are all the dual eccentricities in your company of the bidirectional type?
Eccentric butterfly valves are divided into single-direction sealing and double-direction sealing types. . . Unless otherwise specified, it is generally a one-way seal. The API609 Class B butterfly valves you mentioned are all double-sealed; which standard specifies this – API609 or API598?
I checked the standards; it’s specified in API598. . . He was referring to the elastic seals used in API609 Class B butterfly valves, for which dual-sealing tests are required. The sealing mechanisms in eccentric butterfly valves mainly include elastic seals and multi-layer seals. . . . . Our company has also been manufacturing American-standard butterfly valves for 7-8 years, always using a multi-layer hard-seal design; the design standards specified in the drawings are API609. We have exported to many countries, and no customer has requested a dual-seal test to be carried out. . . The key might lie in this elastic seal. . . .
Is there any image available to take a look at? Does the so-called two-way nature mean that there are no requirements regarding the installation direction?
Yes, there is such a statement in API598: elastic seals (Class 609 B) are required to undergo a double-seal test. The key question now is whether all double-eccentric soft-sealed valves can be called elastic-sealing butterfly valves Are they all Class B?
As specified in API 598, all elastomeric-sealed butterfly valves (Class B) must undergo a double-seal test; in other words, all eccentrically mounted, elastomeric-sealed valves need to have this double-seal testing done
There is no problem in both directions, but the stress levels differ between them.
Is a multi-layer seal also considered a hard seal? In my opinion, aside from metal seals, any seal that uses non-metallic materials can only be considered a soft seal; I think multi-layer seals also fall under the category of elastic seals