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HANDWHEEL
The spoked
handwheel is fabricated from steel pipe. The hub is coupled
with the yoke sleeve by means of a key. Larger valves are
equipped with a bevel or spur gear gearbox unit.
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YOKE SLEEVE
The yoke sleeve is made from cast aluminium bronze having high
resistance to wear and a high melting point. It is designed to
simplify removal from the bonnet or the yoke whilst the valve is
in service. Gate valves 6" class 600 and above are fitted
ball thrust bearings.
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GLAND
AND FLANGE
They are in forged steel and are supplied in two pieces, self
aligning design in order to allow the gland to slide parallel to the stem
even if the eyebolts are unevenly tightened.
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GLAND
BOLTS AND NUTS
The forged steel gland bolts are of the eyebolt type which can
be swung outward for ease of gland repacking. They are fixed
to the bonnet by hinge pins.
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 BONNET
BOLTING
Bonnet studs and nuts are manufactured from alloy steel to the
relevant ASTM standard. The body to bonnet connection is designed
according to ASME VIII DIV 1 standard.
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BODY The body
is cast in carbon or stainless steel and is available in many other
CRA. It is carefully designed for total reliability and simple
maintenance. The
basic dimension, i.e. wall thickness, face to face and flanges
comply with the relevant API and ANSI standards. The body-to-bonnet
flange is circular, expect in the Class 150 which is oval. The
body-to-bonnet joint are flat face on Class 150 valves,
male-and-female on Class 300 and ring joint on Class 400 and above.
The body is basically supplied with renewable seats. Bosses are provided for
drain taps or by-pass piping.
The internal surfaces in contact with the fluid can be fully lined
or cladded for improved corrosion or erosion resistance.
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 BONNET
As the body, the bonnet is
cast in carbon or stainless steel and is available in many other
CRA. It is machined to accept yoke sleeve
and incorporates a stuffing box sized in accordance with the
API standard.
Lifting lugs can be provided integrally cast on the bonnet surface.
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 BONNET
BUSHING
The bonnet bushing or backseats is part of the valve trim. Its
design allows valve repacking without valve's bleeding or draining.
Hardfacing can be provided on stem seating surface.
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STEM
The stem is part
of the trim and is available in a wide range of material in
accordance to API 600 or customer's requirements. The stem is provided
with a T-shaped head. A ground backseat is provided to ensure a perfectly
tight seal to the stuffing box when the valve is fully open. The
stem is highly finished in order to minimize friction and prevent damage to
the
packing. The thread is trapezoidal ACME type. All the stem sizes comply
with the API 600 standard.
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 SEAT
RINGS Welded-in
seat rings are supplied as a standard. The rings are part of the
trim of the valve. They can be externally threaded and internally notched
for easy installation and dismantling. Special attention is given to the
sealing surface which are ground and lapped for a tight seal.
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WEDGE
The wedge is the main part of the trim. It is forged steel or alloy for
diameters up to 12" and is in cast for larger valves. It
is normally supplied as the solid wedge type. It is connected to the
stem by means of a T -shaped joint. The guides on each side of the wedge are
machined. Special care is given to the seating surfaces which
are ground and lapped, integral or handfaced.
A cladding or lining can be applied to the wedge to improve its
resistance against erosive and corrosive environments. For improved
seating and unseating easiness, it can be machined with the flexible
option.
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| REMARKS:
A lantern ring is furnished only on request, in this case the
stuffing box shall be drilled, tapped and fitted with an 1/4"
NPT plug or grease fitting. |
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