4 Valve Description
21 of 72
0570.81/22-EN
Wedge/disc holder 367 is screwed onto stem 200. A retainer prevents wedge discs 360
from twisting in wedge/disc holder 367. To prevent twisting of the obturator
components, the wedge/disc holder is guided in the body by lateral guide ribs 752.
The valve is equipped with a pressure seal bonnet.
The pressure inside body 100 presses bonnet 139 against joint ring 411.1, which is
supported by compression ring 501. Studs 902.2 and hexagon nuts 920.6, which are
supported by thrust plate 414, ensure that bonnet 139 is held in position against joint
ring 411.1, even if there is no pressure inside body 100.
For fitting a body pressure relief valve, (
Section 4.5.1, Page 21) (see type series
booklet 7300.1) a connection branch 131.2 with connection dimensions Ø 22 mm /
14.1 mm (or 12.3 mm) is welded to body 100. The connection branch is supplied
closed.
Body pressure relief valves, if ordered, are supplied unassembled, i.e. attached loosely
to the gate valve.
Instead of fitting a body pressure relief valve, the operator may also provide a means
of pressure balancing between the body’s middle section and the gate valve’s
pressurised connection branch, e.g.:
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a pressure balancing hole in the seat ring or
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an external balancing line.
In this case the gate valve can be used for one flow direction only.
If gate valves and swing check valves in pressure seal design (bonnet 139) are fitted in
close proximity to one another, meaning that the trapped liquid could heat up if the
valves are closed, the operator must fit a body pressure relief valve.
Gland packing 461, which seals off stem 200, is tightened via gland follower 452 by
means of studs 902.3 and nuts 920.1. Stem 200 is moved in the axial direction by the
rotating threaded bush 544, which is fitted with cylindrical roller bearings 323. Stem
200 lifts off wedge discs 360 or presses them against seat rings 515.
Threaded bush 544 is positioned in the yoke head by intermediate flange 729 and
hexagon socket head cap screws 914.1. Handwheel 961 sits on threaded bush 544, to
which it is keyed using key 940. It is secured by circlip 932.
The stop nut 920.3 fitted on stem 200 serves as a travel stop in closing direction. It
prevents jamming of the wedge assembly in the seat and is secured by parallel pin
562.3.
Fig. 9:
Parallel discs
Unlike wedge gate valve designs, slide gate valves feature two parallel discs 368,
which are flexibly mounted in disc holder 367. The discs are supported and pressed
against seat rings 515 by replaceable disc springs 950.1 with parallel pin 562.1.
4.5 Body pressure relief valve
4.5.1 UGS
Fig. 10:
UGS
4.5.1.1 General description
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Body pressure relief valve
4.5.1.2 Design details
Design
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Body made of forged steel
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Stainless steel valve disc (UGS and UGSV)
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Adjustable, needle bearing supported spring assembly (UGS and UGSV)
