A stopper is a valve that controls the opening, closing, or flow regulation of a fluid channel by rotating the stopper valve. Here are the details:
The opening and closing element of plug valve are plunger-shaped, usually cylindrical or conical, with a rectangular or trapezoidal passage design. By rotating the stopper 90 degrees, the channel on the stopper is aligned (opened) with the channel on the valve body to control the flow of fluid. Some plug valves,such as three-way and four-way valves, can be designed with multiple channels for media diversion or flow switching.
II. Structural characteristics of body and plug
Body: Contains and supports plug, usually connected to piping system. Materials include cast steel, stainless steel and alloy steel.
Plug: Cylindrical or conical design with a finely machined surface to reduce friction. Conical valve plugs is sealed by matching their conical surface to the valve body, while cylindrical stopper is sealed by direct contact.
Sealing Types
Soft seal: rubber, plastic and other soft materials, suitable for low pressure, roomtemperature, corrosive media. It has good sealing performance but poor temperature resistance.
Hard seal: use of metal, ceramics and other hard materials. High temperature resistance, high pressure resistance, but the sealing surface easy to wear and tear, require regular maintenance.
Oil-Lubricated Seal: by injecting grease, reduce opening and closing torque, improve sealing performance, form oil film. Suitable for high pressure environment.
Multi-Channel Design
Plug valves may be designed as straight, triple or four-pass valves. One valve can achieve two, three or even four flow channels, simplifying piping systems and reducing the number of valves required.
III. Classified and applicable options
By Channel Type
Straight: Fluid flows in a straight line with low resistance and is suitable for cutting off media.
Three-way/ four-way: Used for the diversion, merging or reversal of media, widely used in chemical and petroleum processes.
By Sealing Type
Soft seal stopper valve: suitable for corrosive, toxic and hazardous media such as food and pharmaceutical products.
Hard seal plug valve: suitable for high temperature, high pressure, abrasive medium such as oilfield exploitation and gas transmission.
Lift plug valve: reduces surface wear by lifting and rotating mechanism, suitable for long distance piping.
By rated pressure: Low pressure stopper: Nominal pressure ≤ 1.6MPa, nominal diameter ≤ 300mm, temperature ≤ 200°C, applicable to municipal, water, etc.
High pressure stopper: Nominal pressure under 64MPa, temperature ≤ 340°C, suitable for high pressure conditions such as oilfields, chemical plants, etc.
IV. INTRODUCTION Performance Advantages:
Simple structure: fewer parts, easy to manufacture and maintain.
Fast opening and closing: A 90-degree rotation to complete the opening and closing action, suitable for frequent operation.
Low fluid resistance: Straight-through design reduces pressure drop and improves system efficiency.
Medium adaptable: can handle suspension and high-viscosity media (e.g. mud, grease).
Flexible installation: may be installed horizontally or vertically without media flow restriction.
V. Scope of application
Petrochemical Industry: control the flow of crude oil, chemicals, liquefied petroleum gas and other media.
Power industry: Adjusts fluid media, such as boiler feedwater and steam.
Food and pharmaceutical industry: Stainless steel is used to ensure liquid purity (e.g., milk and juice production lines).
Water treatment: Controlling the flow of sewage to and from the entrance and use as a pipe stopper valve.
Natural gas transmission: distributes the flow of media in branch pipes to ensure safe operation of the system.
VI. INTRODUCTION Selection Recommendations
Low pressure, small caliber: soft seal is preferred for direct insertion valve, low cost, good sealing performance.
High pressure, high temperature conditions: oil lubrication hard seal or pressure balance plug valves to ensure pressure resistance and wear resistance.
Corrosive media: use stainless steel or plastic-lined plug valves to prevent media contamination.
Multi-flow requirements: choose three or four pass plug valves according to process flow to simplify pipeline design.
