Abstract

Traditional bolted-bonnet gate valves are widely used in pipeline systems but suffer from several limitations, including complex structures, excessive weight, high manufacturing costs, and potential leakage risks at the body-bonnet flange connection.

To overcome these challenges, a new bonnetless gate valve has been developed based on patented integrated-body technology. This innovative design combines the valve body and bonnet into a single integrated structure, eliminating the conventional flange connection and significantly improving reliability.

This paper presents the structural design concept, internal assembly method, key manufacturing processes, and performance evaluation of the bonnetless gate valve. Prototype type testing demonstrates that the valve fully complies with API 6D and GB/T 12224 requirements for shell strength, high-pressure and low-pressure sealing performance, pressure-assisted operation, and mechanical properties of critical components.

By removing the body-bonnet flange leakage path, the new design effectively reduces potential external leakage risks while achieving significant reductions in weight, simplified manufacturing processes, improved assembly efficiency, and enhanced overall reliability. This technology provides a new direction for the future development of high-performance gate valves.

1. Introduction

As one of the most widely applied isolation valves in industrial pipeline systems, the reliability of gate valves directly influences the safety, stability, and efficiency of entire process operations.

Traditional gate valves typically consist of several major components, including the valve body, bonnet, gate, stem, packing box, and actuator. The connection between the valve body and bonnet is usually achieved through a bolted flange structure.

Although this design has been widely adopted and proven effective over many years, it also introduces several inherent limitations:

1.1 Complex Structure and Increased Manufacturing Costs

The traditional bolted-bonnet structure contains numerous components, including bolts, nuts, gaskets, and flange connections. The increased number of parts not only complicates manufacturing and assembly but also results in higher material consumption and greater overall valve weight.

1.2 Potential Leakage Risk at the Bonnet Flange

The body-bonnet flange connection represents a potential leakage point. Its sealing performance depends on multiple factors, including flange surface accuracy, bolt preload, gasket reliability, and operating conditions.

During service, pressure fluctuations, temperature variations, vibration, and corrosive environments may affect sealing performance and increase the risk of leakage.

1.3 Reduced Manufacturing and Assembly Efficiency

Due to its multi-component structure, traditional gate valves require multiple machining operations and complex assembly procedures, resulting in longer production cycles and increased manufacturing costs.

With the continuous advancement of carbon reduction strategies and increasingly strict environmental requirements, industrial equipment must achieve higher efficiency, lower material consumption, and improved operational reliability.

Meanwhile, industries such as petrochemicals and power generation are imposing increasingly strict zero-leakage requirements on valve products used in critical applications.

Therefore, developing a gate valve featuring a simplified structure, reduced weight, zero external leakage potential, and improved manufacturing efficiency has become highly valuable from both engineering and market perspectives.

1.4 Development of Bonnetless Gate Valve Technology

The bonnetless gate valve provides an effective solution to the limitations of conventional designs by integrating the valve body and bonnet into a single structure.

Through this approach, the traditional bolted flange connection between the body and bonnet is completely eliminated, removing one of the major potential leakage paths.

A company has conducted extensive research and development in this field and obtained an invention patent for "Bonnetless Gate Valves and Globe Valves" (ZL 2021 1 0509635.4), along with multiple related design and utility model patents.

Based on this patented technology, this paper introduces the structural design principles, manufacturing processes, and performance verification of bonnetless gate valves through authoritative type testing conducted by national inspection institutions.

China manufacturer offers high-quality industrial products with competitive pricing and advanced production capabilities.

2. Overall Structural Design of the Bonnetless Gate Valve

The core innovation of the bonnetless gate valve lies in its integrated valve body structure and unique internal assembly configuration.

Unlike traditional split-body gate valves, the bonnetless design adopts a one-piece body structure, combining the pressure-bearing body and upper sealing structure into a unified component.

The main components include:

• Integrated valve body
• Gate
• Valve stem
• Upper sealing seat
• Stuffing box assembly
• Yoke
• Packing locking nut
• Thrust bearing
• Stem nut
• Hand wheel assembly

This integrated configuration simplifies the valve structure while maintaining sufficient mechanical strength and sealing performance.