Parallel Slide Valves

Parallel valves consist of two discs which maintain contact with the parallel body seats with a light spring. It uses line pressure to effect a tight closure. Temperature changes in the line are accommodated by the flexibility of the disc assembly and therefore do not affect the operation of the valve


Parallel Valves by John Valves

Parallel slide valves, renowned for their robustness and precision, are pivotal components in many industrial settings. These valves, characterised by their unique design featuring two parallel discs, provide a secure and tight seal, particularly in high-pressure and high-temperature environments. Their operational efficiency stems from a design that ensures optimal sealing and minimises wear and tear through a self-cleaning mechanism during operation. This blend of durability, reliability, and versatility makes them indispensable across various sectors.

From power generation to chemical processing and water management to HVAC systems, parallel slide valves are integral in ensuring the smooth and safe operation of critical processes. Their widespread application across diverse industries highlights their essential role in contemporary industrial operations, marking them as critical enablers in the functionality and efficiency of modern infrastructure and manufacturing processes.

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Parallel Slide Valve Products

Parallel Slide Gate
Item Details
Body Material
Carbon Steel (WCB)
Body Coating
Pressure Range
Size Range
Flange Connection
AS2129 Table D,E,F,H&J / ANSI
End Connection
Higher Pressure Rating / Trim Materials

Parallel Slide Valve Technical Sheets

Our commitment to industry to supply parallel slide valves, we have made these technical sheets available. If you need further information please make a technical enquiry.

Parallel Slide Valve

Cast Steel Parallel Slide

The John FIG 316S valve features a unique design with two discs held in contact with parallel body seats by a light spring between them. This design leverages line pressure to achieve a secure and tight closure. The construction of the disc assembly is notably flexible, allowing it to adapt to temperature variations in the pipeline without impacting the valve’s functionality. 

An added benefit of this design is observed during the opening or closing of the valve; as the discs move, they slide across the seat faces. This motion effectively dislodges any foreign particles that might be present, thus maintaining a clean and efficient seal. Additionally, the valve is equipped with an outside screw operating stem, which ascends through the handwheel, ensuring easy and reliable operation.

Ball Valves Illustration

Excellence in the Design & Engineering

Excellence in the design and engineering of parallel slide valves is a testament to the intricate balance of precision, functionality, and innovation in industrial mechanics. In these valves, every component is crafted with utmost precision, ensuring that they operate seamlessly under varying pressures and temperatures. 

The engineering prowess is evident in the sophisticated mechanism of the parallel discs, which slide to create a perfect seal, a crucial factor in maintaining system efficiency and safety. Advanced materials and manufacturing techniques further enhance their durability and reliability. 

Moreover, the design of these valves incorporates considerations for ease of maintenance and longevity, making them a cost-effective and reliable choice in critical applications. 

The attention to detail in the design and engineering of parallel slide valves epitomises the commitment to excellence, setting a benchmark in the field and reflecting a deep understanding of the dynamic challenges in industrial fluid management.

Operation Mechanism

The operating mechanism of parallel slide valves is a marvel of engineering, showcasing a blend of simplicity and efficiency. Two parallel discs that move in unison within the valve body are central to their function. These discs come together when the valve is closed, forming a tight seal against the parallel seats.

This action is facilitated by a mechanism often controlled by a handwheel or actuator, translating rotational motion into linear motion of the discs. What sets this design apart is how the discs slide across the seat faces during operation, effectively clearing any debris and ensuring a clean, secure seal. This sliding action is crucial for maintaining the integrity of the seal but also minimises wear and tear, thereby enhancing the valve’s lifespan.

Additionally, using line pressure in these valves aids in achieving a tighter seal, making them particularly effective in high-pressure environments. This intricate yet robust mechanism ensures reliable performance, making parallel slide valves a preferred choice in various industrial applications where precision and durability are paramount.

Advantages and Applications

  • Enhanced Sealing Capability
    The unique design of parallel slide valves, with their parallel discs, ensures a more effective seal than traditional valves. This is particularly advantageous in high-pressure environments where a tight seal is crucial.
  • Reduced Wear and Tear
    The sliding action of the discs across the seat faces during operation helps in self-cleaning and minimises damage caused by debris. This results in less wear and tear, extending the valve’s life.
  • Temperature Adaptability
    These valves can efficiently handle temperature variations, thanks to their design, which accommodates thermal expansion and contraction. This makes them suitable for applications involving temperature fluctuations.
  • Improved Safety
    Due to their reliable sealing and robust construction, parallel slide valves are considered safer, especially in high-pressure and high-temperature applications, reducing the risk of leaks or failures.
  • Ease of Maintenance
    The straightforward design of these valves makes maintenance and inspections more manageable, thereby reducing downtime and maintenance costs.

Industry Uses

In environments with high pressure and extreme temperatures, these valves stand out for their robust performance, ensuring safety and efficiency in critical processes. Their unique design, featuring parallel discs that provide a precise seal, is pivotal in managing fluid flow across various industries.

This versatility is a testament to their adaptability and the ingenious engineering behind their development. From energy production to water treatment and chemical processing to HVAC systems, parallel slide valves are not just components; they are vital cogs in the machinery of modern industry, playing a crucial role in maintaining the smooth operation of numerous industrial applications.

Their widespread use across diverse sectors underscores their importance and the trust industries place in their consistent and reliable operation.

Oil & Gas Sector

The oil and gas industry relies on these valves for the safe and efficient transport and processing of hydrocarbons. Their robust design is ideal for handling the high-pressure systems used in upstream, midstream, and downstream operations, including pipelines, refineries, and processing plants.

Chemical Processing​

Parallel slide valves are essential in the chemical industry due to their ability to handle corrosive materials, extreme pressures, and temperatures. They ensure precise control and isolation in processes involving aggressive and hazardous chemicals.

Water and Wastewater Treatment​

These valves are used in water treatment plants and wastewater management systems for regulating flows and maintaining pressure. Their reliability and durability make them suitable for these critical public infrastructure systems.

Food and Beverage Manufacturing​

In food and beverage production, these valves help maintain hygienic conditions and precise control over processing temperatures and pressures.


Precision is critical in pharmaceutical manufacturing, and ball valves precisely control medical product processing. ​

Power Generation

In power plants, particularly those involving steam generation, parallel slide valves play a critical role. They are used for controlling steam flow, managing high-pressure and high-temperature conditions, and ensuring reliable operation of turbines and other critical components.

Marine Applications​

Used in marine applications, particularly in the engine rooms of ships for controlling steam for propulsion and other onboard systems.

HVAC Systems​

In heating, ventilation, and air conditioning systems, especially in large commercial or industrial settings, parallel slide valves are used to control the flow and pressure of steam or hot water used in heating systems.

Pulp and Paper Industry​

In the paper and pulp industry, these valves control the flow of steam and chemicals used in the processing and manufacturing of paper products, where precise temperature and pressure control is necessary.

Mining & Minerals

In mining, they are employed for steam and water control, essential in processes like mineral processing and extraction.

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Frequently Asked Valve Questions

If would like to know more, please get in touch and we’ll be happy to answer your questions.

A parallel slide valve is a type of valve used in industrial applications, characterised by two parallel discs that come into contact with matching seat faces to form a seal. This design is especially effective in handling high-pressure and high-temperature environments.

While both are used for similar applications, the key difference lies in their sealing mechanism. Parallel slide valves use two parallel discs that slide into place, creating a tight seal and minimising wear. In contrast, gate valves use a single gate lifted out of the way for flow.

heir primary advantages include enhanced sealing capability, reduced wear due to the sliding action of the discs, adaptability to temperature changes, and ease of maintenance.

 They are widely used in industries such as power generation, oil and gas, chemical processing, water treatment, and HVAC systems, among others.

 Yes, one of the key strengths of parallel slide valves is their ability to accommodate temperature changes without affecting their performance, thanks to the flexibility in their disc assembly.

Absolutely. These valves are designed to provide a tight seal under high-pressure conditions, making them ideal for applications where pressure management is critical.

The sliding action helps in self-cleaning the seating area by dislodging any debris, which reduces wear and tear and ensures a more effective seal.

 No, these valves are designed for ease of maintenance. Their simple yet robust design allows for easy inspection and repair, reducing downtime and maintenance costs.

Yes, manufacturers often provide options for customisation to meet specific requirements of different industrial applications.

By providing reliable and leak-proof operation, especially in high-pressure and high-temperature conditions, parallel slide valves play a crucial role in ensuring the safety of industrial processes and operations.