Design and Manufacture:Cast steel gate valve to API600(ISO10434)or API 6d;Cast stainless steel gate valve to API603 or API 600;Forged steel gate valve to API 602;
Inspection and Test:API 598;API600 or API 6D;
End flange dimension:ASME B16.5(for NPS≤24)、ASME B16.47 series B、API605 or ASME B16.47 series A、MSS SP-44(for NPS> 24).
BW end dimension:ASME B16.25
Socket-weld dimension:ASME B16.11
Face to face and end to end:ASME B16.10
Pressure-temperature ratings:ASME B16.34
Gasket of Cover Flange
Carbon steel or stainless stell+flexible graphite combined gasket is used for Class 150 gate valve;Stainless steel+flexible graphite wounded gasket is used for Class 300 gate valve;Stainless steel+flexible graphite wounded gasket is used for Class 600 gate valve,and ring joint gasket is also optional for Class 600 gate valve;Ring Joint gasket is used for Class 900 gate valve;Pressurized seal design is used for Class 1500-Class 2500 gate valve.
Molded flexible graphite is used for packing material.Ptfe or combined packing material can be also used if being requested by the customer.The internal surface of the stuffing box,of which area is contacted with the packing,is of excellent finish(Ra3.2 um).The stem surface,contacting with the packing,should be rolled and pressed after being precisely machined,so as to reach to the high finish and compactness(Ra0.8 um)and ensure the reliable tightness of the stem area.
Body and Bonnet Connection
The body and bonnet of Class 150-Class900 gate valves are usually connected with studs and nuts.And the body and bonnet of Class 1500-Class2500 gate valves are usually of pressurized seal design.
Hand wheel or gear box is usually used for gate valve actuation.Chain wheel and electric actuator can be also used for gate valve actuation if being requested by the customers.
Design of Disc
Gate valves with NPS≥2 ARE OF WEDGE FLEXIBLE GATE;Gate valves with NPS<2 are of wedge solid gate.
Back Seating Design
All our gate valves have the back seating design.In most cases ,the carbon steel gate valve is fitted with a renewable back seat.For stainless steel gate valve,the back seat is machined directly in the bonnet or is machined after welding.When the gate valve is at fully open position,the sealing of the back seat can be very reliable.However,as per the requirement of API600,it is not advisable toad or change packing by the mean of back seating when the valve is pressure containing.
The stem is of integral forged design.The minimum diameter of the stem shal per the standard requirement.The connection of the stem and disc is T type.The strength of the connecting area is bigger than that of the T theeaded par of the stem.The strength test of that area conforms to API591.
Usually Carbon steel or stainless steel + flexible graphite combined gasket is used for Class150 gate valve; Stainless steel + flexiblegraphite wounded gasket is used for Class 300 gate valve; Stainless steel + flexible graphite wounded gasket is used for Class600 gate valve, and ring joint gasket is also optional forClass600 gate valve; Ring Joint gasket is used for Class 900 gate valve; Pressurized seal design is used for Class1500 ～Class500 gate valve.
For carbon steel gate valve, the seat is usually forged steel.The sealing surface of the seat is spray welded with hard alloy specified by the customer. Renewable threaded seat is used for NPS ≤ 10 gate valves, and welded on seat can be also optional if being requested by the customer. Welded on seat is used for NPS ≤10 carbon steel gate valves. For Stainless steel gate valve, integral seat is usually adopted, or to weld hard alloy directly integrally. Threaded or welded on seat is also optional for stainless steel gate valve if being requestedby the customer.
Special Gate Valve
Besides the normal wedge gate valves, gangye also offer Extension Stem Gate Valve, Cryogenic Gate Valve,Jacketed Gate Valve, and Bellow Sealed Gate Valve for many kinds of application.