Specification

Standards

Design and Manufacture: Cast steel gate valve to API 600(ISO10434)or API 6D(IS014313) Cast stainless steel gate valve to API 603 or API 600(IS010434) Forged steel gate valve to API 602.

Inspec tion and Test: API 598, API 600 or API 6D

End flange dimension: ASME B16.5(for NPS<24): ASME BI6.47 series B API 605 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 BI6. 10

Pressure-temperature ratings: ASME B16. 34.

 Design of Disc

 Gate Valves with NPS=2 are of flexible wedge gate; Gate valves with NPS 2 are of solid wedge gate

 Body and Bonnet Connection

 The body and bonnet of Class 150-Class 900 gate valves are usually bolted bonnet design. And Class 1500-class 2500 gate valves are usually of pressurized seal design

 Gasket of Cover Flange

 Carbon steel or stainless steel 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.

 Actuation

 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

 Packing Seal

 Molded flexible graphite is used for packing material. PTFE or combined packing material can be also used if being requested by the customer. The intenal surface of the stuffing box, of which area is contacted with the packing, is of excellent finish (Ra 3.2 m). 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 (Ra 0.8 m )and ensure the reliable tightness of the stem area

 Belleville Spring Loaded Packing Impacting System

 If being requested by the customer, the Belleville spring loaded packing impacting system can be adopted for enhancing the durability and reliability of the packing seal

 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 AP 600, it is not advisable to add or change packing by the mean of back seating when the valve is pressure containing

 Seat

 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. Welled 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 requested by the customer

 Stem Design

 The stem s of integral forged design. The minimum diameter of the stem shall 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 threaded part of the stem. The strength test of that area conforms to API 591

 Stem Nut

 Usually, the stem nut is made of ASTM A439 D2. it is also can be made of copper ally if being requested by the customer. For large sized gate valves( NPS 10 for Class 150, NPS 8 for Class 300, NPS 6 for Class 600, NPS 5 for Class 900), rolling bearing is fitted at the two sides of the stem nut in order to minimize the open and close torque of the gate valve

 Special Gate Valve

 Besides the common gate valves, my Company also makes cryogenic gate valve, Jacketed Gate Valve, Bellow Sealed Gate Valve, Extension Stem Gate Valve for underground application, Flat Gate Valve, etc.