Gate Valves
Bolted Bonnet Gate Valve
API 600 cast steel gate valve with bolted bonnet — the workhorse for general isolation in refinery and process piping.

Overview
A bolted bonnet gate valve is a type of valve used to control the flow of fluids in piping systems. It features a bonnet that is bolted to the valve body, securing the internal components such as the gate, stem, and seating surfaces.
Key features
- Carbon Steels, Low Temperature Carbon Steel, Martensitic Steels, Austenitic Stainless Steel, Duplex Stainless Steels, Super Duplex Stainless Steels, Nickel Alloys, Nickel Aluminum Bronze, Hastelloy, Inconel, Titanium Alloy & Carbon Steel with Internal Corrosion Resistant Alloy (CRA) Overlay
- Carbon Steels, Low Temperature Carbon Steel, Martensitic Steels, Austenitic Stainless Steel, Duplex Stainless Steels, Super Duplex Stainless Steels, Nickel Alloys, Nickel Aluminum Bronze, Hastelloy, Inconel, Titanium Alloy & Carbon Steel with Internal Corrosion Resistant Alloy (CRA) Overlay
- Design and Construction:
- Gate Mechanism: Operates by raising or lowering a gate (wedge or parallel disc) to control flow.
- Bonnet: Securely holds internal components and allows for maintenance.
- Body: Designed for durability and often made from robust materials like carbon steel or stainless steel.
- Operation:
- Rising Stem: The stem rises and lowers with the gate, providing a visual indication of the valve position.
- Bi-Directional Flow: Allows fluid to flow in both directions when open.
- Sealing Mechanism:
- Metal-to-Metal Seal: Provides a tight shut-off to prevent leakage when closed.
- Flexible Wedge Design: Adapts to changes in temperature and pressure for reliable sealing.
- Applications:
- Suitable for a wide range of fluids including water, oil, steam, gases, and more.
- Used in pipelines, refineries, chemical plants, power plants, and other industrial settings.
- Pressure and Temperature Ratings:
- Designed to handle high-pressure applications up to ANSI Class 2500 and beyond.
- Can withstand temperatures ranging from cryogenic to high-temperature environments.
Technical specifications
- Size Range
- 2 – 56 NPS, DN50 - DN1400
- Body Materials
- Temperature Range
- -29°C to 650°C
- Trim Materials
- Maximum Allowable Operating Pressure
- ASME 150# to 2500#
- Pressure-Temprature Rating
- ASME B 16.34
- Construction Details
- Bolted Bonnet
- Body Style
- Flanged End, Butt Weld
- Design Standard
- API 600, BS 1414, API 6D
- Flange Drilling
- ASME B16.5
- Testing Standard
- API 598, API 6D, ISO 5208, API6FA, ISO 10497,BS6364
- Face To Face
- ASME B16.10
- Applications
- Refineries,Hydrocarbon,Energy and Process industries.
- Operation
- Handwheel, Gear, Actuator (Pneumatic, Hydraulic, Electro-Hydraulic and Electric Motorised)
Applications
- Refineries
- Hydrocarbon
- Energy and Process industries.
Benefits
- Reliability:
- Provides a straight-line flow path with minimal pressure drop when fully open.
- Offers dependable shut-off capabilities due to the metal-to-metal sealing.
- Versatility:
- Suitable for both high and low-temperature environments, accommodating various industrial processes.
- Can be used in systems requiring infrequent operation or in applications where flow control is critical.
- Durability:
- Constructed from durable materials capable of withstanding harsh operating conditions.
- Designed for longevity and minimal maintenance requirements.
- Safety:
- Ensures safe operation with reliable shut-off capabilities, preventing potential hazards in industrial processes.
- Provides clear visibility of the valve’s status due to the rising stem design.
- Maintenance:
- Bonnet design allows for easy access to internal components, facilitating inspection, repair, and replacement.
- Regular maintenance ensures continued performance and extends the valve’s service life.
Frequently asked questions
These valves are used in various industries including oil and gas, petrochemical, power generation, water treatment, and more. They are suitable for applications requiring bi-directional flow control and where a tight shut-off is necessary.
They are commonly made from materials such as carbon steel, stainless steel, bronze, and alloys like Monel or Inconel. The material choice depends on factors like the fluid type, pressure, temperature, and environmental conditions.
Proper installation, regular maintenance, and selecting the appropriate valve size and material are crucial for preventing leakage. Ensuring the gate and seating surfaces are in good condition and properly aligned when closed also helps maintain a tight seal.
They are available in a wide range of sizes, typically from 1/2 inch to 24 inches or larger, and can handle pressure ratings up to ANSI Class 2500 or higher, depending on the design and manufacturer specifications.
While gate valves are primarily used for on/off control due to their design, they can be used for throttling in certain conditions where flow control is not critical and where erosion and cavitation are not concerns.
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