Pipeline Ball Valve
(API Spec
6D) Production Range:
Valve Type:
trunnion-mounted, quarter-turn, soft-seated, fire-safe
design
Body Constructions: Welded body and Split-body type and
Top-Entry type
Size: 6" to 48" (DN150~1200) and larger
Type: WB1 &
WB, BB1, BT
Rating: ANSI Class 150# to 900# (PN20 to
PN150)
Temperature: -60C to 250C (-76~482°F)
Service:
shutoff
Basic
Standards:
Design and Tests:
API 6D & DIN 3230
Fire-Safe: tested
design to API 607 and API 6FA and BS 6755: Part2
Materials: ASTM,
DIN
Application Scopes:
Oil, Gas and
Water Pipelines: Main & Transfer Lines, Manifolds, Compression
& Pumping Stations, Launcher & Receiving Traps, Metering Systems.
Offshore: Subsea Pipelines
Standard
Features:
Double Block and Bleed: the fluid entrapped in the valve
body is bleedable with the ball in fully closed position to API Spec 6D
provisions.
Valve Bore: Valve are of full or reduced bore design.
Reduced bore is of Venturi type. Minimum bore size is to API 6D
requirements.
Body Structure: The manufacture of the body is of three
types: split-body or welded-body or top-entry. The split or welded body
design is used for valve side-entry type. It consists of three forged
steel pieces joined by bolting or welding respectively. The body of valve
top-entry type is made of one cast steel piece.
Antistatic Design:
Stainless steel springs ensure the electrical continuity between all the
valve metal parts (e.g. body, ball, seat rings and stem) which could be
isolated by elastomeric or thermoplastic seals.
Pressure unbalanced ball
: Unless otherwise requested, no hole is provided for the ball to
equalize the pressure of the fluid in the pipeline to the one of fluid
entrapped in the body cavity when the valve is open. It enables a
preventive maintenance, allowing the check of the ball seating efficiency
in any valve position, with no modification of the pipeline working
condition.
Anti-blowout stem design: The stem, detachable from the
bal, is blow proofed thanks to an integral abutment resting against the
bonnet through a self-lubricating thrust washer.
Bi-directional seat
rings: Each seat ring is independent floating type and suitably
designed to shutoff the fluid aside from its pressure distribution through
the valve. So both seat rings constitute a double barrier to the fluid,
because of the downstream seat ring ensures shutoff of the fluid in case
the upstream one fails. As any overpressure of the fluid entrapped in the
valve body cannot be released back into the pipeline, a relief valve is
fitted to the vent connection if the handled fluid is a
liquid.
Ball seating: Valves with rating lower than ANSI Class 1500# have a
seat insert made of elastomer to enable double ball sealing: a primary of
metal-to-metal and a secondary of soft type (Fig.a). Valves with higher
rating are provided with a seat insert made of thermoplastic resin (like
Nylon or filled PTFE) to ensure a soft bubble-tight only against the ball
(Fig.b). In addition, a double plastic+elastomer seal is recommended for
valves having a stainless steel trim with no plating to be used in very
low pressure service (Fig.c).
Double Seal of stem: Two
elastomeric O-rings provided with backup in PTFE perform a double
stem barrier to the fluid. The outer O-ring can be replaced with the valve
under pressure.
Emergency seals: Both
seals of stem and seat rings can be reinstate in case of damaging by
injecting a suitable sealant grease through ports machined in the valve
body and bonnet. Grooves and channels are machined in the seat rings
suitably to distribute the sealant along the damaged seals. Check valves
are buried into the injecting ports, which are equipped withgiant button
head fitting for a fast connection to a greasing pressure gun.
Operability: All valves
are operable with a manual gearbox or with any quarter-turn power actuator
type.
Fire-safe tested design: It is a standard provision for all valve
models. The use of fluorocarbon elastomer (like Viton) with no graphite
backup for trim and flanged body joints enables the valves to overcome
fire testing. Test certificates are available on request.
Bleeding
Joints: Each valve is provided with drain and vent ports, which are
plugged or valved to meet the requested serviceability.
Optional
Self-relieving seat
rings: When any overpressure of the fluid entrapped in the valve body
shall be automatically relieved back into the pipeline, valves are
equipped with seat rings of self-relieving design.
Stem Extensions: Valves
to be installed underground or buried are equipped with a stem extension
assembly, whose outer casing is equipped with relief valve and drain plug.
Connections for bleeding and sealant injection of the valve body are
suitably extended with valved piping too.
Transition pieces or
pups: Valves to be connected to pipeline by welding in accordance with
special procedure or subjected to thermal stress relieving (P.W.H.T) are
equipped with pups made of pipe or forging.
Sour Service: Valve are
supplied with materials in compliance with NACE MR-01-75
requirements.
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