Butt Weld Pressure Seal Globe Valve

Butt Weld Pressure Seal Globe Valves integrate internal system pressure to secure body-bonnet sealing under extreme temperature and pressure conditions. Designed for rigid piping systems in severe services, these valves feature full-penetration welded ends that eliminate potential mechanical joint leak paths.

Pressure-Assisted Bonnet Joint: Internal fluid pressure drives the flexible graphite or metallic seal ring tighter against the body inside diameter, increasing seal integrity as system pressure rises.

Hermetic Weld Connections: Butt weld end preparation per ASME B16.25 forms a continuous, permanent pipe-to-valve connection resistant to thermal cycling and line stress.

Hardfaced Seating Interface: Cobalt-base Stellite No. 6 hardfacing applied via Plasma Transferred Arc (PTA) welding on both seat and disc surfaces prevents erosion, galling, and wire-drawing under high differential pressures.

Guided Disc Mechanism: Fully guided stem and disc assembly maintains coaxial alignment throughout the stroke length, minimizing vibration and seat deformation during throttling.

Non-Rotating Stem Design: Acme-threaded stem combined with heavy-duty needle thrust bearings lowers operating torque and protects stem packing from rotational wear.

Body Architecture: Cast or forged heavy-wall pressure boundary engineered to absorb structural piping loads, hydraulic shock, and sudden temperature shifts.

Bonnet Retaining Assembly: Includes bonnet thrust ring, segmented key rings, and a precision-machined pressure seal gasket positioned inside the body chamber.

Gland Packing Structure: Two-piece self-aligning gland flange prevents stem binding caused by angular misalignment or thermal expansion.

Integral Backseat: Precision-machined backseat allows stem packing isolation in the fully open position.

Flow control relies on linear stem displacement driving the disc perpendicular to the body seat. Turning the handwheel or operating the actuator advances the stem, pressing the Stellite-faced disc against the body seat for positive shutoff or positioning it off the seat for flow regulation. System pressure acting against the lower side of the bonnet forces the pressure seal ring upward against the body wall, forming a pressure-tight barrier.
 

End Welding Profiles: Standard bevel profiles per ASME B16.25 to match Schedule 80, Schedule 160, XXS, or specified pipe wall dimensions.

Body Flow Profiles:
Straight-Through T-Pattern for compact installation footprints.
Y-Pattern angled body structure reducing internal turbulence and pressure drop by up to 40 percent.
90-Degree Angle Pattern serving as an elbow replacement in high-pressure header lines.

Manual Control: Heavy-duty handwheel with impactor mechanism or spur/bevel gearboxes for high differential pressure operation.

Electric Actuation: Multi-turn electric actuators equipped with torque switches, position transmitters, and field network interface units.

Pneumatic Actuation: Linear spring-return or double-acting pneumatic piston actuators with digital valve positioners and air filter regulators.

Hydraulic Actuation: High-thrust electro-hydraulic actuators for fast emergency shutdown or precise modulating control.

Design Compliance: ASME B16.34, API 623, BS 1873.

Pressure Testing: Hydrostatic shell test at 1.5 times nominal pressure and high-pressure seat closure test per API 598.

Non-Destructive Examination (NDE):
• 100 Percent Radiographic Testing (RT) or Ultrasonic Testing (UT) on pressure-retaining castings and forgings.
• Dye Penetrant Testing (PT) or Magnetic Particle Testing (MT) on butt weld bevel preparations and Stellite overlay surfaces.

• Quality Certifications: Material Test Reports per EN 10204 3.1, CE/PED 2014/68/EU, ISO 9001, SIL 2/3 Safety Integrity Certification.

Fossil Power Generation: Main steam lines, boiler feed water regulation, hot reheat isolation, and turbine bypass control.

Nuclear Power Facilities: Secondary circuit main steam isolation and high-pressure water treatment piping.

Refining & Hydroprocessing: Hydrocracker units, catalytic reformers, high-pressure hydrogen feed systems, and gasification plants.

Chemical Processing: High-temperature synthesis gas loops and thermal fluid lines under extreme thermal shocks.

Identify Operating Parameters: Define maximum operating temperature, design pressure, fluid chemical characteristics, and required flow coefficient (Cv).

Select Body Material:
Carbon Steel (WCB/A105) for non-corrosive steam and water service under 425°C.
Chrome-Moly Alloy Steel (WC9, F22, F91) for high-temperature steam applications up to 600°C requiring creep resistance.
Stainless Steel (CF8M/F316) for corrosive fluids or low-temperature media.

Specify Pipe Connection Profile: Match the valve weld bevel inside diameter and wall thickness directly to the matching pipe schedule to ensure penetration depth during field welding.

Choose Body Configuration: Select T-pattern for inline space constraints or Y-pattern to lower system head loss.

Calculate Operating Torque: Evaluate differential shutoff pressure to select manual gear operators or automated actuators.

Material Test Reports (MTR) according to EN 10204 3.1 verifying heat chemical composition and mechanical properties.

NDE examination reports covering RT, UT, PT, and MT results.

Hydrostatic and pneumatic seat/shell pressure test certificates detailing hold duration and gauge calibration data.

Welding Procedure Specification (WPS) and Procedure Qualification Record (PQR) for hardfacing and body joining processes.

Dimensional inspection reports confirming weld bevel dimensions meet ASME B16.25 standards.

Customized weld bevel preparations and extended pups to support field stress-relieving heat treatments.

Live-loaded stem packing systems using Belleville spring washers to maintain constant packing compression during thermal cycling.

Custom center-to-face dimensions matching existing piping layouts for replacement projects.

Specialized trim contours including equal percentage or quick-opening disc profiles for custom flow control needs.

Customized surface preparation, protective paint systems, and stainless steel identification tagging.