Cast Steel Wedge Gate Valve with Bypass Valve — API 600 / DIN, HF Seal, for Steam Service

This cast steel wedge gate valve is fitted with an integral bypass valve for steam service. The bypass is a smaller valve connected across the main gate; opening it first equalizes pressure on both sides of the wedge before the main gate is opened. On large-size and high-pressure steam lines, this reduces the torque required to open the main valve and protects the seating surfaces from pressure-related damage during operation.

The valve is available to two standard sets: API 600 / API 6D with ASME B16.5 / B16.47 flanges and ASME B16.10 face-to-face, or DIN3352 with DIN3202 face-to-face, DIN2543–2545 flanges and DIN3230 testing. Sizes run from NPS 2" to 36" (DN50–DN900), with ratings from ANSI Class 150LB to 2500LB or DIN PN10 to PN64. Body materials cover carbon steel, low-temperature carbon steel, alloy steel and stainless steel, as listed in the material table below.

Standards

API / ASME Standard Set

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.

DIN Standard Set

Quick Details

1. Type: Bypass Gate Valves
2. Design: OS&Y, Bolted Bonnet, Solid or Flexible Wedge Design
3. Size Range: 2" – 36", DN50 to DN900
4. Pressure Ratings: ANSI Class 150LB – 2500LB, DIN PN10 – PN64
5. Materials Available in: Cast Steel GS-C25, 1.4308, 1.4408, 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
8. NACE MR0175 on request

Selection Notes: Bypass Function, API vs DIN and Steam Service

The bypass valve is the defining feature of this page. A closed wedge gate valve at high differential pressure requires significant torque to crack open, and the seating surfaces can be damaged if the main gate is forced open against full differential pressure. The bypass equalizes pressure first, so the main gate opens with lower torque and less wear. This is why bypass gate valves are commonly specified for large-size, high-pressure steam lines and for valves that are opened infrequently.

API or DIN: the two standard sets are not interchangeable at the flange and face-to-face level. API 600 / API 6D valves use ASME B16.5 or B16.47 flanges and ASME B16.10 face-to-face dimensions; DIN3352 valves use DIN2543–2545 flanges and DIN3202 face-to-face dimensions. The required standard set, pressure rating and flange facing must be stated together with the size when the valve is specified.

Steam service: for standard steam, A216 WCB with an HF hard-faced seal is the usual selection. For high-temperature steam, A217 WC6, WC9 and C5 are the alloy steel options. For low-temperature service, A352 LCB is available. For corrosive or high-purity steam, A351 CF8, CF8M, CF3 and CF3M stainless steel bodies are available. NACE MR0175 / ISO 15156 compliance is available on request for sour service; the H₂S partial pressure, operating temperature, CO₂ content and chloride concentration are needed to confirm the material and hardness specification.

Features

1. Bonnet Gasket Style
Stainless steel + flexible graphite combined gasket;
Stainless steel + flexible graphite wound gasket;
Ring joint gasket;
Pressurized seal design.

2. Packing Seal
Flexible graphite is used for packing material. PTFE or combined packing material can also be used.

3. Body and Bonnet Connection
Bolted Bonnet design (B.B).

4. Operation
Hand wheel or bevel gear box is usually used for gate valve operation. Electric actuator can also be used if requested by the customer.

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

6. Backseat Design
All gate valves have backseat design.

7. Stem Design
The stem is integral forged design.

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.

Bypass Gate Valve Design Drawing

Parts and Material List

Material table normalized to nine material columns: WCB, LCB, WC6, WC9, C5, CF8, CF8M, CF3, CF3M. The original header used a colspans that did not match the listed materials; this has been corrected for readability.

Frequently Asked Questions