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BEIER control valves for cryogenic service
is applied in 200 sets of air separation equipment.we have a long
term research in cryogenic service,have enough of technology to
guarantee the valve’s sealing reliability,operating agility,and
other special capability in low temperature service..
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Technology introduction
BEIER control valves for cryogenic service,can get over the
leakage,main two condition of leakage: inner leakage and external
leakage.
1)the reason of valve’s inner leakage is that the seal pair have
deformation in low temperature service.When the temperature of media
falled to make material changed,and it’s changed in volume ,the seal
surface have warpage from original high precision grinding,then
that’s the case of sealing badness in low temperature.
The new designed butterfly valve have been changed from plane seal
to conical surface seal.seat ring have a oblique cone oval sealing
surface,with the circular resilient sealing ring wedged above the
valve disc composed seal pair.sealing ring can be floated in groove
of disc.as valve shutdown, resilient sealing ring contacted with
minor axis of elliptical sealing surface.along with turn of stem,
progressive pulled sealing ring entad,made resilient sealing ring
contacted with major axis of oblique cone oval sealing
surface.finally made resilient sealing ring full contacted with
elliptical sealing surface.The sealing is depended on the
deformation of resilient sealing ring. Thereby as it’s happened of
body and disc deforming in low temperature.the deformation will be
absorbed and compensated,It’s haven’t happened that case of leaking
and over tightening.as valve is open,the resilient deformation will
disappeared,and as in the shutdown process basically havn’t relative
friction,it’s the cause valve have a long service term.
2) the external leakage of valve:one of the cause is flanged type
body connection,as a result of it’s connection bolt,connection
parking and connector is loose to be leaking in low temperature
services.therefore we changed the body connection type from flanged
to welding connection,to avoid leakage in low temperature
services.the second cause is the leakage between stem with packing
part.commonly the packing of most valve is F4,cause the
self-slipping stability,little friction coefficient,and special
chemical stability,so have a wide appliance.but the shortage of F4
is that:great inclination of cold flow, high linear expansion
coefficient, bringing shrinkage in low temperature result in
leakage,made mass of freeze on the stem part,result in turning on
valve unsuccessful.and our control valve for cryogenic service have
self-shrinking sealing structure,using F4 high expansion coefficient
point,by the remaining clearance to reach the sealing purpose in
high-and-low temperature services. |
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