Class 300 Stainless Steel Gate Valve — A351 CF8 (SS304), Wedge Sluice, Flanged RF/RTJ, NPS 2"–36"

This Class 300LB stainless steel gate valve is the flanged, rising stem (OS&Y), bolted bonnet design with a solid or flexible wedge and backseat. The body, bonnet, wedge, seat ring and gland flange are cast in ASTM A351 CF8 (SS304); the stem is A182 F304, with A193 B8 bolting and A194 8 nuts. Flanged ends are to ASME B16.5 with either raised face (RF) or ring type joint (RTJ) facing; face-to-face dimensions are per ASME B16.10, pressure-temperature ratings per ASME B16.34. Sizes run from NPS 2" to NPS 36". The valve is supplied with a handwheel as standard; a bevel gear operator is available for large sizes on request. The model designation Z40W refers to a stainless steel body with the seat integral with the body material, as distinct from Z40H (carbon steel, hard-faced).

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); ASME B16.47 series A / MSS SP-44 (for NPS > 24).
Face to face and end to end: ASME B16.10.
Pressure-temperature ratings: ASME B16.34.

Quick Details

1. Type: Flanged gate valves, model Z40W
2. Design: OS&Y, bolted bonnet, solid or flexible wedge design
3. Size Range: 2" to 36" (DN50 to DN900)
4. Pressure Rating: ASME Class 300 / 300#
5. Body Material: Cast stainless steel A351 CF8 / SS304
6. Various trim materials are available to suit different service conditions
7. Actuator: Manual, handwheel (bevel gear available on request)
8. Special Requirement: NACE MR0175 on request

Selection Notes: CF8/304 vs CF8M/316, Z40W and RF vs RTJ

CF8 (304) vs CF8M (316): CF8 corresponds to AISI 304 stainless steel; CF8M corresponds to AISI 316. The key difference is the molybdenum addition in CF8M, which significantly improves resistance to chloride pitting and crevice corrosion. This page covers the CF8 (304) version, which is suitable for mildly corrosive media where chlorides are not present. For seawater, chloride-bearing process fluids and more aggressive corrosive service, the CF8M (316) version is normally specified. Internals change accordingly: CF8 valves use A182 F304 stems and A193 B8 / A194 8 bolting, while CF8M valves use A182 F316 stems and A193 B8M / A194 8M bolting.

Z40W model interpretation: Z denotes gate valve, 4 denotes the flange connection, 0 denotes the structural form (rising stem, bolted bonnet), and W denotes the sealing surface material — in this case the seat is integral with the CF8/SS304 body material, which is why the designation uses W (stainless steel) rather than H (hard-faced carbon steel). Compared with Z40H (carbon steel, hard-faced), the Z40W is the stainless steel version of the same API 600 rising-stem gate valve.

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 on this page.

Features

1. Bonnet Gasket Style
Stainless steel + flexible graphite combined 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. Disc Design
NPS ≥ 2 gate valves are flexible wedge gate.

5. 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.

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

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

Swipe horizontally to see all materials

Parts No. 5: original source used "b" instead of "5" — corrected. Gland Eyebolt (Parts No. 9): original source had "ASTMA193 B8" without a space — corrected to "ASTM A193 B8". Parts No. 21 Set Screw: original source lists ASTM A193 B7 in the CF8 column; this is retained as the original bill of materials, and is confirmed against the material certificate at the time of order. Nipple, Yoke Sleeve Nut, Hand Wheel and Hand Wheel Nut are shown as carbon steel / ductile iron because these parts are not wetted and do not change with the body material.

Main Connection Dimensions — Class 300LB (mm)

Swipe horizontally to see all dimensions

Dimensions in mm. L = face-to-face dimension (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 for NPS > 24. This page covers the flanged RF/RTJ configuration; the BW column is included for reference when the same valve is specified with butt-weld ends. NPS 38 and 40 are not listed in the original Class 300 dimension series.

Frequently Asked Questions