In the context of ongoing energy infrastructure development under the Belt and Road Initiative, long-distance natural gas pipeline projects place higher requirements on critical valve equipment.
Recently, Zhejiang RAYS Flow Control successfully completed the batch delivery of pneumatic-hydraulic fully welded ball valves for a natural gas pipeline project in Uzbekistan. The delivered valves cover DN50–DN1400 | PN80, with the largest size reaching 56 inches and a single valve weight exceeding 35 tons. The valves are designed for high-pressure, long-distance natural gas transmission service.
As one of the few domestic export references for 56" | Class 600 natural gas pipeline ball valves, this project represents an important milestone for the RAYS ball valve product line and demonstrates RAYS’ capability in supporting international energy infrastructure projects.
A Systematic Challenge Behind a Large-Diameter Pipeline Valve
In natural gas transmission, a 56-inch fully welded ball valve is a representative large-diameter and high-pressure pipeline valve. When the Uzbekistan project started, RAYS was not facing a standard pipeline valve order, but a system-level project covering design, process engineering, manufacturing, quality control, testing, and delivery.
At the early project stage, RAYS quickly organized its engineering, manufacturing, quality control, and project management teams to work together. The team focused on four key areas: pressure-bearing structure, seat sealing system, low-torque design, and pneumatic-hydraulic actuator control.
During the design stage, RAYS engineers used 3D modeling and finite element analysis to evaluate key components such as the valve body, extended stem, actuator, and connection parts. In addition to conventional pressure and temperature conditions, seismic load conditions were also simulated to verify structural safety and pressure boundary reliability from the design stage.
Engineering Design and Structural Verification
The valves adopt a forged fully welded body and bonnet design, improving overall strength and toughness. This structure helps the valve withstand and transfer pipeline stress and system pressure while maintaining connection and sealing reliability.
For the ball design, RAYS engineers carried out deformation calculations under large-diameter and high-pressure conditions. This helps prevent ball deformation from affecting sealing contact and supports long-term sealing stability in gas pipeline service.
Multi-Layer Sealing for API 6D Zero Leakage Requirements
In long-distance natural gas pipelines, sealing performance is a key factor for safe operation. For this project, the valves adopt a multi-layer seat sealing structure to improve long-term sealing reliability.
Elastomer primary sealing: designed to meet API 6D zero leakage requirements.
Quasi-metal sealing: protects the primary sealing system.
PEEK supporting seal: helps share axial thrust and reduce the risk of metal galling.
In addition, the valves are designed with DBB functionality in the fully closed position, allowing online seat sealing tests and cavity drainage without interrupting pipeline operation.
Low-Torque Design for Reliable Long-Term Operation
Emergency shut-off valves in long-distance pipelines remain open for most of their service life. In addition to sealing performance, reliable operation after long-term standby is also critical.
RAYS reduces valve operating torque through optimized stem load structure, sealing design, bearing configuration, ball machining accuracy, and surface treatment.
Key low-torque design features include:
Low initial sealing force design
Low-friction PTFE self-lubricating bearing
High-precision ball machining with coaxiality and roundness controlled within ≤0.02 mm
Chemical nickel plating on the ball surface for wear resistance and reduced friction coefficient
Through the combined control of sealing, bearing, machining accuracy, and surface treatment, RAYS improves the operating reliability of large-diameter, high-pressure pipeline ball valves.
Manufacturing, Testing, and Reliable Delivery
During production, RAYS integrated engineering, machining, inspection, and assembly processes into a closed-loop quality control system. Key components such as valve bodies and seats were precision-machined by large imported CNC machining centers and inspected by coordinate measuring machines to control dimensional accuracy.
Before delivery, each valve completed shell pressure testing, seat sealing testing, opening and closing tests, torque calibration, and pneumatic-hydraulic actuator function tests. These inspections ensure that the valves meet the requirements of long-distance natural gas pipelines for emergency shut-off, remote operation, and rapid response under abnormal conditions.
Supporting Energy Infrastructure Projects Worldwide
From design verification to manufacturing and testing, the Uzbekistan natural gas pipeline project demonstrates RAYS’ systematic capability in large-diameter, high-pressure fully welded ball valves.
RAYS will continue to support natural gas transmission, oil and gas storage and transportation, and critical energy infrastructure projects worldwide with reliable flow control solutions.
