API 602 ASME B16.34 CE 4″ 300LB Carbon Steel WCB Flanged Angle Type Manual Bellows Seal Globe Valve

II. Manufacturing Process, Key Features

A. Manufacturing & Quality Control

• Casting & Forging: The WCB body and bonnet are cast using precision lost-wax casting techniques, followed by heat treatment (normalizing) to achieve optimal mechanical properties, including a minimum yield strength of 240 MPa and tensile strength of 485-655 MPa. All castings undergo 100% visual inspection and non-destructive testing (NDT) including magnetic particle testing (MT) and ultrasonic testing (UT) to detect surface and internal defects.
• Machining: Critical sealing surfaces (seat, disc, and bellows mating surfaces) are precision-machined to a surface finish of Ra 0.8 μm or better, ensuring tight shut-off and minimal wear. The valve stem is ground to a tolerance of ±0.02 mm, ensuring smooth operation and alignment with the bellows assembly.
• Bellows Assembly: The multi-layer stainless steel bellows (typically SS316L) is laser-welded to the stem and bonnet using automated orbital welding equipment, eliminating manual errors and ensuring consistent weld quality. Each bellows unit undergoes helium leak testing at 1×10⁻⁹ mbar·L/s to verify zero leakage.
• Assembly & Testing: The valve is assembled in a clean environment, with all components torqued to specified values using calibrated tools. Every valve is subjected to hydrostatic shell testing at 1.5 times the rated pressure (750 psi / 5.17 MPa) and seat leakage testing at 1.1 times the rated pressure (550 psi / 3.79 MPa) per API 598, ensuring structural integrity and shut-off performance. A final fugitive emission test per ISO 15848-1 is conducted to confirm the bellows seal’s performance under cyclic operation.

B. Key Product Features

• Zero Fugitive Emissions Bellows Seal: The primary feature of this valve is the multi-layer metallic bellows seal, which completely eliminates the traditional stem packing, preventing any leakage of hazardous, toxic, or volatile fluids to the atmosphere. The bellows is designed for a minimum of 10,000 open-close cycles, ensuring long-term reliability even in high-cycle applications.
• Angle Pattern Flow Path: The 90-degree angle design optimizes flow control in process lines where piping direction changes are required, reducing the need for additional elbows and minimizing pressure drop across the valve.
• Robust WCB Construction: ASTM A216 WCB cast carbon steel provides excellent strength and impact resistance, suitable for high-pressure and high-temperature applications up to 425°C. The material is widely compatible with water, steam, oil, and most non-corrosive industrial fluids.
• Bolted Bonnet with Gasket Seal: The bonnet is secured to the body with high-strength alloy steel bolts, using a spiral-wound graphite gasket to provide a secondary static seal, enhancing safety and reliability in high-temperature service.
• Precision Throttling Control: The contoured disc and seat design of the globe valve provides linear flow characteristics, making it ideal for throttling applications where precise flow regulation is required, unlike ball or gate valves which are primarily for on-off service.
• Low Maintenance Design: The elimination of packing gland adjustments reduces routine maintenance requirements, while the modular design allows for easy replacement of the bellows and trim components without removing the valve from the pipeline.
• Compliant with International Standards: The valve is designed, manufactured, and tested in accordance with API 602, ASME B16.34, and CE directives, ensuring compatibility with global industrial projects and easy acceptance by engineering, procurement, and construction (EPC) contractors worldwide.