내부유체의 패킹실에서 외부에 누출을 방지하기 위해 Bellows Seal을 Stem의 축봉부에 용접으로 장착한 밸브이다.Bellows Seal 밸브의 용도는 열매체등의 악취 유체, 위험성 유체, 독성 유체, 진공등의 배관에 적용된다.기본적으로 급속하거나 빈번한 개폐 조작을 중요시 하지 않는 배관에 사용된다.
■ YOKE SLEEVE
The upper portion of the Yoke Sleeve is hexagonally tapered to fix the handwheel. The standard material of the Yoke Sleeve is Nodular Ni-resist D2 with over 1150℃(2100℉) dissolution point in accordance with API Std. specifications.
The body-bonnet bolts are manufactured in accordance with API Std. 600 specifications. The nuts also strictly conform with ANSI B 1.1 The stud-bolt nuts, hexagonal, rigid and hot-forged, bear material notation as well as do the bolt nuts made according to ANSI B18.2.2
The bonnet and valve body have the same wall thickness. The body-bonnet flange drilling is spot-faced to exactly meet studbolt nuts. The bonnet back seat bushing guarantees packing replacement even when the valve is fully opened. The stem packing dimensions of the stuffing box are in accordance with API specifications.
The machined forged stem comes with a T-shape head, which connects the slot of the wedge. The spherically shaped contacting surface of the head gives greater strength and durability. The stem dimensions are in accordance with API Std. 600 specifications. The heat treated stem delivers adequate mechanical properties as well as excellent surface hardness. Further, opening/shutting friction is minimized by accurate machining and lapping.
■ SEAT RING
Bottom seated type seat rings are welded or screwed into the body. The seating surface is finished by lapping. They are forgings that have been heat treated to delived the best mechanical properties and required hardness. The difference in hardness between seats and wedge is in accordance with API specifications.
■ FLEXIBLE WEDGE
The standard disc of our valves is a one-piece flexible wedge. Slots are machined on both sides of the wedge to allow it to travel correctly in the integrally cast body guides. The wedge seating surfaces have been accurately machined, grind and lapped to a mirror finish to prevent leakage and eliminate galling.
The cast steel body is designed to insure a wall thickness which is greater at any point than the minimum specified by API Std. 600 or API 603. Special care has been taken with the design of the Class 150 valve body so that the elliptically shaped center section is free from intensified stresses in the critical area. The body of above Class 300 are made circular in shape as much as possible to minimize distortion even under extreme operating conditions. Inlet and outlet port dimensions conform with ANSI B16.5 Pipe Fitting. The welded-in type seat ring is standard to insure interchangeability. Except for Class 150, the standard body-bonnet joint is male