An API 602 forged gate valve is used for compact, small-bore gate valve service in petroleum, natural gas, chemical, power, and industrial piping. To specify the right design, confirm size, pressure class, material, bonnet type, end connection, port type, trim, seat, testing standard, and service conditions.   What Is an API 602 Forged Gate Valve?   An API 602 forged gate valve is a compact steel gate valve manufactured to API 602 requirements. API 602 covers gate, globe, and check valves for sizes DN 100 / NPS 4 and smaller in petroleum and natural gas industry applications. Unlike large cast steel gate valves, forged gate valves are usually selected for smaller piping systems where pressure, temperature, vibration, or compact installation matters. Forged construction provides a dense material structure, which is useful for high-pressure and critical service. In simple terms, API 602 is often the better fit when the line is small but the service is demanding.   When Should You Use an API 602 Forged Gate Valve?   Use an API 602 forged gate valve when the application requires reliable isolation in a compact piping system. It is commonly used in refineries, chemical plants, power plants, oil and gas facilities, steam lines, vents, drains, and utility systems.   Typical use cases include: ● Small-bore high-pressure lines ● Steam and condensate service ● Process isolation ● Skid-mounted systems ● Drain and vent connections ● Instrument and auxiliary piping ● Oil, gas, and petrochemical service   For larger line sizes or heavy-duty cast steel applications, API 600 may be more appropriate. API 602 and API 600 should not be treated as interchangeable standards.   Key Design Choices to Specify   Do not specify an API 602 forged gate valve only by size and pressure class. The purchase requirement should define the full valve design. Important items include: Item What to Confirm Size DN / NPS size and bore requirement Pressure class Class 800, 1500, 2500, or project requirement Material A105, F304, F316, F11, F22, LF2, or other grade Bonnet type Bolted bonnet, welded bonnet, or pressure seal End connection Socket weld, threaded, butt weld, or flanged Port Full port or regular port Trim Stem, wedge, seat, and hardfacing material Operation Handwheel, gearbox, or actuator if required Testing API 598 or project-specified testing   These details affect sealing, pressure capability, maintainability, and installation.   Bonnet and End Connection Selection   Bonnet type should match pressure, temperature, and maintenance needs. Bolted bonnet designs are common and easier to service. Welded bonnet designs reduce potential leakage paths but are less convenient to disassemble. Pressure seal bonnets may be considered for higher-pressure service, depending on the design and project requirement.   End connection is equally important. Socket weld ends are common for small-bore forged valves. Threaded ends may be...

The main butterfly valve types include concentric, double offset, triple offset, wafer, lug, flanged, soft-seated, metal-seated, manual, pneumatic, and electric butterfly valves. The right choice depends on pressure, temperature, media, leakage requirement, installation space, and operation frequency.   What Are the Main Butterfly Valve Types?   Butterfly valves are usually classified by disc design, body connection, seat material, and actuation method. This classification is important because two valves may both be called butterfly valves, but their service limits can be very different.   A butterfly valve uses a rotating disc to isolate or regulate flow. Because of its compact structure, light weight, and quarter-turn operation, it is widely used in water treatment, power plants, chemical processing, HVAC, marine systems, and general industrial pipelines.   For buyers, the key question is not simply “which type is cheaper?” It is “which type can handle the actual pressure, temperature, media, and sealing requirement?”   Concentric Butterfly Valve   A concentric butterfly valve has the stem located on the centerline of the valve body and disc. It is also called a centerline butterfly valve. This type is commonly used for low-pressure and general-service applications, especially with water, air, and non-aggressive fluids. It is simple, economical, and easy to maintain.   The limitation is seat wear. During opening and closing, the disc stays in contact with the soft seat for much of its movement. For higher pressure, higher temperature, or stricter shutoff requirements, double offset or triple offset designs are often more suitable.   Double Offset Butterfly Valve   A double offset butterfly valve uses two offsets to reduce friction between the disc and seat. This improves sealing performance and helps extend service life compared with a basic concentric design.   Double offset butterfly valves are often selected for medium-pressure industrial service, including oil and gas, water supply, power generation, and chemical systems. They are useful when the application needs better durability but does not require a full metal-seated triple offset design.   This type is also commonly called a high-performance butterfly valve. Before selection, buyers should confirm the pressure class, seat material, shaft sealing design, and expected operation frequency.   Triple Offset Butterfly Valve   A triple offset butterfly valve adds a third geometric offset to create a more advanced sealing structure. It is typically used for high-temperature, high-pressure, or severe-service applications. The design reduces rubbing between the sealing surfaces during operation. Many triple offset butterfly valves use metal seats, making them suitable for steam, oil and gas, chemical, and other demanding media.   For these applications, standards and testing matter. Buyers often need t...

A triple offset butterfly valve is a high-performance isolation valve designed for applications where conventional resilient-seated or double offset butterfly valves cannot meet pressure, temperature, or leakage requirements. By using a three-offset sealing design, the valve achieves a metal-to-metal sealing mechanism with reduced friction between the disc and seat during operation, making it suitable for demanding services such as oil and gas, petrochemical, power generation, LNG, steam, and industrial process systems.   Triple Offset Butterfly Valve Design and Working Principle   Unlike a concentric butterfly valve, where the shaft is positioned at the centerline of the disc and seat, a triple offset butterfly valve incorporates three independent geometric offsets. The first offset moves the shaft away from the centerline of the valve body, the second offset shifts the shaft from the pipeline centerline, and the third offset introduces a conical sealing surface instead of a circular sealing profile. This geometry allows the disc to move away from the seat immediately after rotation begins, eliminating rubbing between sealing surfaces.   The main advantage of this design is that the sealing force is generated by torque rather than continuous compression of soft materials. If the application requires high-temperature service, then a metal-seated triple offset butterfly valve is often preferred because elastomer seats may degrade under elevated temperatures. If the medium contains abrasive particles or aggressive chemicals, then material selection for the disc, seat, and body becomes critical to prevent erosion, corrosion, and leakage during long-term operation.   Triple Offset Butterfly Valve Standards and Materials   A triple offset butterfly valve is commonly manufactured according to standards such as API 609, EN 593, and ISO 5752, with pressure ratings ranging from Class 150 to Class 600 and higher depending on design requirements. Typical materials include carbon steel, stainless steel, duplex stainless steel, aluminum bronze, and nickel-based alloys. For corrosive seawater applications, aluminum bronze alloys such as C95500 or C95800 may be selected, while sour service applications may require materials compliant with NACE MR0175/ISO 15156 requirements.   Triple Offset Butterfly Valve Sealing Performance and Leakage Control   The sealing performance of a triple offset butterfly valve depends on the interaction between the sealing ring, seat surface finish, operating torque, and material compatibility. Since the sealing surfaces contact only at the final closing position, mechanical wear is significantly reduced compared with traditional butterfly valve designs. If zero leakage is required for critical isolation, then the valve design, pressure class, and applicable leakage standard, such as API 598 or ISO 5208, must be considered during specification.   Triple Offset Butterfly Valve Applications and S...