Class 300LB Cast Steel Gate Valve (Z40) — WCB / CF8 / CF8M, RF / RTJ / BW Ends, NPS 2"–36"

This Class 300LB cast steel gate valve is the API 600 rising stem (OS&Y) bolted bonnet design with a flexible wedge and backseat. The standard body is ASTM A216 WCB; ASTM A351 CF8 (304) and CF8M (316) bodies are available for corrosive service. End connections include raised face (RF) and ring type joint (RTJ) to ASME B16.5, butt-weld to ASME B16.25, and socket-weld to ASME B16.11. Sizes run from NPS 2" to NPS 36". Class 300 is commonly specified in oil and gas production, refinery and petrochemical service where pressures exceed Class 150 but do not require Class 600.

Application

Class 300 cast steel gate valves are commonly specified in oil and gas production and gathering, refinery and petrochemical process lines, water treatment and medium-pressure utility service. For sour service the valve can be supplied to NACE MR0175 / ISO 15156 on request; RTJ ends are frequently combined with NACE compliance at this class.

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.

Quick Details

1. Type: Gate Valves, model Z40
2. Design: OS&Y, Bolted Bonnet, Flexible Wedge Design
3. Size Range: 2" to 36" (DN50 to DN900)
4. Pressure Ratings: ASME Class 300LB / 300#
5. Materials Available in: WCB, LCB, CF8, CF8M, CF3, CF3M, WC6, WC9, C5, C12 or equivalent
6. Various trim materials are available to suit different service conditions
7. Actuator: Manual, Handwheel, Gear Operated
8. Special Requirement: NACE MR0175 on request

Selection Notes: Class 300 vs Class 150, RF vs RTJ and Trim Choice

Class 300 vs Class 150: the class number refers to the ASME pressure-temperature rating of the valve body and flanges per ASME B16.34 and ASME B16.5. Class 300 has thicker walls and heavier flanges than Class 150 and is rated for higher pressure at the same temperature. For the same nominal pipe size, a Class 300 valve has a larger face-to-face dimension than a Class 150 valve of the same size, so the two are not dimensionally interchangeable in the line. The dimension table below lists the Class 300 series only.

RF vs RTJ at Class 300: RF (raised face) is the standard ASME B16.5 connection and remains the default for non-sour oil and gas, water treatment and general petrochemical service. RTJ (ring type joint) uses a metal ring gasket seated in a machined groove, providing a metal-to-metal seal that is preferred for high-pressure, high-temperature and sour service and is commonly specified together with NACE MR0175. This valve is available with both facings; the face-to-face dimensions differ between RF and RTJ, as listed in the Class 300 dimension table.

Trim choice on the WCB version: Trim 1 (13Cr seat and 13Cr wedge) is the standard selection for general service. Trim 5 (Stellite on seat and wedge sealing surfaces) is preferred where erosion and wear resistance is required, such as throttling duty or high-velocity lines. Trim 8 (13Cr wedge with STL seat) is a middle-ground specification frequently requested in refinery and petrochemical line schedules.

Features

1. Bonnet Gasket Style
Stainless steel + flexible graphite wound gasket is used for Class 300 gate valve.

2. Packing Seal
As usual, flexible graphite is used for packing material. PTFE or combined packing material can also be used if requested by the customer.

3. Body and Bonnet Connection
Class 300LB gate valves are usually connected with bolted bonnet design.

4. Operation
Hand wheel or bevel gear box is usually used for gate valve operation.

5. Disc Design
NPS ≥ 2 gate valves are flexible wedge gate.

6. 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 machined after welding.

7. Stem Design
The stem is integral forged design. The minimum diameter of the stem shall be as per the standard requirement.

8. Stem Nut
Usually, the stem nut is made of ASTM A439 D2. It can also be made of copper alloy or other materials if requested by the customer.

9. Seat
For carbon steel gate valve, the seat is usually forged steel. The seat sealing surface is overlay welded with hard alloy specified by the customer. For stainless steel gate valve, the seat is integral with body, or it can be machined directly after hard alloy welding.

Cast Steel Gate Valve Parts and Material List (Class 300LB)

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Main Connection Dimensions — Class 300LB (mm)

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Dimensions in mm. L = face-to-face (RF / RTJ) or end-to-end (BW) per ASME B16.10. RF and RTJ flange dimensions per ASME B16.5 for NPS ≤ 24; ASME B16.47 series A (MSS SP-44) for NPS > 24. The Class 300 face-to-face dimension is larger than Class 150 for the same NPS; the two series are not interchangeable in the line.

Frequently Asked Questions