API Cast Steel Fully Open Gate Valve Metal Seat Z40H For Oil / Gas Industry

Industrial API Cast Steel Gate Valve Metal Seat Fully Open Z40H for Oil and Gas Industry.

1. Standards

Design and Manufacture: Cast steel gate valve to API 600 or API 6D;

Inspection and Test: API 598, API 600 or API 6D.

End flange dimension: ASME B16.5 (for NPS≤24),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 B16.10.

Pressure-temperature ratings: ASME B16.34.

2. Bonnet Gasket Style

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.

3. Packing Seal

As usual, flexible graphite is used for packing matorial. PTFE or combined packing material can be also used if being roquostod by tho customer. The surface roughness belween the packing and packing seal is Ra 3.2  μm, so thal the slem contact the packing surface tightly but rotate freely. The roughness of stem sealing face is Ra 0.8 μm after being precisely machined to ensure the reliable tightness.

4. Body and Bonnet Connection

Class 150 ~ Class 900 gate valves are usually connected with bolted bonnet design.
Class 1500 ~ Class 2500 gate valves usually adopt pressure seal bonnet design.

5. Operation

Hand wheel or bevel gear box is usually used for gate valve operation. Chain wheel and electric actuator also can be used for gate valve operation if being requested by the customers.

6. Disc Design
NPS≥2 Gate valves are flexible wedge gate, NPS<2 Gate valves are solid wedge gate.

7. Backseat Design

All gate valves have backseat 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 be machined after welding. When the gate valve is at fully open position, the sealing of backseat can be very reliable.

8. Stem Design

The stem is integral forged design. The minimum diameter of the stem shall be as 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.

9. Stem Nut

Usually, the stem nut is made of ASTM A439 D2. It is also can be made of copper alloy or other materials if being requested by the customer. For large sized gate valves (NPS ≥10 Class 150, NPS ≥8 Class 300, NPS ≥6 Class 600, NPS≥ 5 for Class 900), rolling bearing is fitted between stem nut and stem in order to minimize the torque for easy operation.

10. Seat

For carbon steel gate valve, the seat is usually forged steel. The seat sealing surface is overlaying welded with hard alloy specified by the
customer. Renewable threaded seat is used for NPS≤10 gate valves, and welded on seat also can be optional if being requested by the customer. Welded on seat is used for NPS≤12 carbon steel gate valves. For Stainless steel gate valve, the seat is integral with body, or it can be machined directly after hard alloy welded. Threaded or welded type seat is also optional for stainless steel gate valve.

11. Parts and Material List