May. 12, 2025
Industrial valves are made up of many different components that allow them to regulate flow. The main parts of a valve designs can be divided into the body, trim, actuators, and ancillary accessories. This table provides a brief overview of the primary valve components and their functions:
With competitive price and timely delivery, YIYUAN sincerely hope to be your supplier and partner.
The valve body, also called the shell, housing, or casing, is the primary pressure boundary of a valve. It serves as the framework that holds together all the other valve parts in proper alignment. Valve bodies are designed to withstand pipeline pressure, temperature, and mechanical stresses. The inlet and outlet of the valve body connect to the piping system. There are various body styles and configurations, with the most common being globular, straight-through, angle, and Y-pattern. The body shape depends on the valve’s intended flow control function. Gate, globe, check, ball, plug, and butterfly valves all have distinctive body designs tailored to their unique flow control application. Valve bodies are cast or fabricated from materials like carbon steel, stainless steel, cast iron, alloy steel, and forged steel. The material is chosen based on the process fluid composition, pressure, and temperature. Many valve bodies have flanged ends to enable connection to piping. Others may have threaded, socket weld, or butt weld ends. No matter the style, the valve body must be strong enough to withstand the system pressure when the valve is in the closed position. It must also be rigid and resistant to warping or cracking that could cause leaks.
There are various options when selecting valve body materials based on the service conditions. Carbon steel is suitable for water, oil, and gas service. Stainless steel handles more corrosive fluids like acids or wet chlorine gas. For extremely high temperatures, alloy steel and cast iron are better choices. Cryogenic valves for frigid liquids like LNG use stainless steel or forged carbon steel bodies. The body material also affects maintenance requirements. For example, carbon steel is prone to rusting or corrosion over time and may need frequent repairs. Stainless steel and alloy steel have higher corrosion resistance, extending the service life. In highly abrasive applications, a hardened valve body is required to resist wearing. No single material is ideal for all applications. Consider fluid composition, pressure, temperature ranges, and desired valve life when choosing a body material. Partnering with an experienced valve supplier is key to getting the right metal for reliable service.
The valve bonnet is the cover on the upstream side that completes the pressure shell of a valve body. It also provides the means for assembling the internal valve parts and accessing them for maintenance. There are three main bonnet configurations: screw, bolted, and welded. A screw bonnet has threads that engage with the body and provides a compact means of assembly. It is easy to open and close for routine inspection and repairs. Bolted bonnets have a separate flanged head that connects to the body using long bolts. This allows very large valves to be assembled in sections. Bolted bonnets are common on gate, globe, and check valves over NPS 2. Welded bonnets have the cover permanently welded to the body. No threads or bolts are used, creating a tight seal. However, this does not allow accessing internal parts without cutting. Welded bonnets are preferred for high pressure and temperature systems where bolts or threads could leak. They also cost less than bolted styles. When selecting a bonnet type, consider the maintenance needs, potential leakage risks, valve size, and expense. The bonnet must withstand system pressure and temperature fluctuations. Leak-proof, easy disassembly and assembly is ideal for most applications.
Valve trim refers to the internal moving parts that modulate flow such as balls, plugs, discs, and gates. The trim comes in contact with the process fluid, so its material must handle the chemical, temperature, and abrasive characteristics. Hardened trim materials include tungsten carbide, Stellite alloys, titanium, Inconel high-nickel alloys, and 440C stainless steel. These withstand highly erosive or corrosive substances. Softer trim materials like bronze, aluminum, Monel, and 304 stainless suit less destructive fluids. The trim material really depends on the fluid composition. For example, a high nickel alloy is better for hydrofluoric acid compared to regular stainless steel. Cryogenic valves need trim that handles freezing temperate without becoming brittle. Abrasive slurries require durable trim that resists wearing. Partnering with an experienced supplier is key to getting the right trim materials for your specific process conditions. This ensures long service life and minimal erosion damage.
Valves use sealing systems to prevent fluid leakage between the stationary body and moving parts. Packing and gaskets are the two main sealing methods. Valve packing consists of rings made of soft, deformable material like graphite, PTFE, or flexible graphite. The rings fit around the valve stem and compress when the bonnet or gland follower tightens. The soft packing deforms to create a tight seal. Packing can leak over time and must be periodically tightened or replaced. It allows some controlled leakage for lubrication. Gaskets provide a more permanent seal between two mating surfaces. Common types are spiral-wound metal, ring joint, kammprofile, and flat paper or plastic. Gaskets require more precision machining for leak-proof performance. Packing handles frequent disassembly better since gaskets can be damaged during maintenance. For fugitive emissions control, metal gaskets are preferred over packing. However, packing enables easy stem movement and regular adjustment. Consider maintenance needs, allowable leakage, and emission regulations when choosing packing or gasket seals.
Gate valves use linear motion gates to start and stop flow. The gate and valve disk can be flexible or solid. Flexible wedge gates have a solid top edge but flexible sides made of metal bellows or laminated sheets. This allows the gate to match the bore when seating, creating a tight seal even on worn valve seats. However, bellows can burst or laminations separate after frequent flexing. Solid wedge gates are a one-piece solid gate that cannot flex. These provide a sturdier gate but require precision machining for effective sealing without leakage. Solid wedges are better for high pressure or frequent operation. Flexible gates suit low pressure modulating control where tight shutoff is needed. Gates must be resistant to cutting, scoring, and deformation from fluids. Flexible gates suit liquids and clean gases. Solid gates work for steam, gases with solids, and contaminated fluids where a bellows could rupture. Consider shutoff requirements, pressure, media properties, and desired service life when choosing between flexible and solid gate designs.
The valve stem translates motion from the actuator to the flow controlling element inside the valve. It may have a rising or non-rising design. Non-rising stems remain vertical as the valve operates. The stem is threaded into the gate, plug, or ball and turns it without lifting. Rising stems lift up and down with valve motion while remaining attached to the flow control element. Rising stems indicate valve position and can automate control via positioners. Non-rising stems require separate shaft position indicators. Rising stems are common on gate and globe valves. Non-rising stems suit ball and plug valves where turning motion is required. Non-rising stems work well for buried valves or corrosive fluids where rising stems could get damaged or cause binding. The stem must align with the actuator and match its torque output. Consider maintenance needs, automation requirements, and environments when selecting between rising and non-rising stem designs.
The backseat is a wearing surface on the valve stem that contacts the bonnet when the valve is fully open. It serves several purposes. First, it provides an additional seal between the stem and bonnet. This isolates the bonnet from system pressure when doing maintenance. It also gives the valve a bidirectional shutoff ability – seal both upstream and downstream. Backseats also enable packing adjustment and replacement while the valve is pressurized. Finally, backseats can act as a stopping point when fully open, preventing damage to seating surfaces. Backseats are common on gate, globe, and check valves. They should have enough surface area to prevent excessive wear. Stainless steel, brass, or carbon graphite materials work well. Consider whether backseats would facilitate safer maintenance when selecting valves. But they aren’t recommended for infrequently operated emergency shutoff valves.
Actuators provide the force to open, close, and position the valve. Common types are linear actuators, quarter-turn actuators, and multi-turn actuators. Linear actuators apply thrust along the stem’s axis to drive gates, globes, or diaphragms up and down. These are often pneumatic cylinders or hydraulic pistons. Quarter-turn actuators rotate 90 degrees to open/close ball, plug, and butterfly valves. Manual lever arms, electric motors, or pneumatic cylinders are common quarter-turn actuators. Multi-turn actuators use gearing to allow for multiple 360 degree rotations. These automate precise positioning of globe and gate control valves. Another benefit of gearing is the high output torque from a small electric motor or manual handwheel. When selecting valve actuators, consider torque requirements, speed, automation needs, space constraints, and hazardous area rating. The actuator output must match the torque demands of the valve, especially for 100% shutoff.
Valves contain many components, and material choices depend on the application. For steam systems, metal seats, bonnets, and steam-rated packing suit the high temperature and avoid oxidation. In cryogenic applications, the body, trim, and seals require materials that stay ductile at freezing temperatures like stainless steel. Highly corrosive fluids need stainless steel or alloy bodies and trim along with corrosion inhibiting sealant on gaskets. For throttling control valves, components supporting smooth stem movement and flow characterization are essential. This includes characterized trims, modified trim geometry, low-friction packings, and high resolution actuators. The principles are the same, but components must be tailored to safely handle the operating conditions. Partnering with an experienced supplier ensures that all valve parts are suited to the service.
Properly selecting valve components requires careful consideration of the service conditions, performance requirements, and desired valve type. Here are some important considerations when choosing valve parts:
For welding end valves, ensure the valve-body ends and weld joint design suit the piping system and materials. Flow mediums that require tight shutoff may need metal-seated ball valves with properly matched stem threads, outside screw and yokes that prevent side loading. High pressure applications need sturdy valve bonnets, thick stem packing in the stuffing box, and sturdy yoke bushings.
Relief valves require precise trim parts and trim designs to provide accurate pressure control. Ball valves used for throttling duties require characterized ball and seats to control flow. The rotational motion of ball and plug valves depends on quality bearings and seals internal elements.
Control valves rely on valves bonnets, gaskets, stem packings and other parts to prevent leakage and enable smooth actuation. The top of the yoke and downstream side covers of a swing-check valve see the most wear, so durable materials are vital.
Choosing control valves also means matching the actuator style and output to provide the right type of motion – rotary for 90 degree ball valves or linear for globe designs. This ensures proper valve positioning and tight shutoff when closed.
No matter the valve type, considering spacing, installation, and maintenance requirements will guide the selection of compact wafer, lugged, or flanged designs. Partnering with experienced suppliers and following PMI standards ensures the parts selected provide long service life.
Understanding how the various internal parts of valves work together is critical for engineers, maintenance staff, and plant operators. The body, bonnet, trim, stem, seals, and actuators all play a role in controlling fluid flow safely and reliably. Component selections must be based on service conditions and performance goals. With the right knowledge of component functions and material differences, industrial valves can be kept in prime operating condition for their essential role in managing fluids.
At their most basic, valves are devices that work to control, regulate or direct flow within a system or process.
They often feature a range of characteristics that help to define their ideal application.
However, whether you’re looking to control flow, provide safety in a system that is piping liquids, solids, gasses or anything in between, there are likely stainless steel valves available to help.
Valves provide several functions, including:
While many valves accomplish similar goals, how they do so mechanically can vary.
How a valve opens and closes will not only impact the overall performance but also determine how much control you have over the flow and how quickly the valve can operate.
Most valves fit into one of three categories:
Are you interested in learning more about Valve Parts Components? Contact us today to secure an expert consultation!
On top of the mechanical motion involved with a valve, also consider the method of actuation. In most cases, valves fall into one of three categories:
Valves feature a range of characteristics, standards, and groupings the help to give you an idea of their intended applications and expected performance. Valve designs are one of the most basic ways to sort the huge range of valves available and finding a good fit for a project or process.
Common types of valves include:
You might also see valves classified by function instead of design.
Common functional designations and their common design types include:
While valves might be a small part of your piping process or system in terms of space, they’re often a substantial portion of the design and build budget. They also have a significant impact on long-term costs and overall system performance.
Choosing a proper valve size is essential to both optimizing costs and ensuring safe, accurate, and reliable operation.
The first thing to consider is the overall size of the valve -- both in terms of physical dimensions and in terms of internal size and flow rates (CV).
Choosing a valve that does not fit properly in the space required could result in added costs. Choosing a valve which does not provide the ideal flow rate can lead to inaccurate flow control at the least and complete system failure at worst.
For example, if your valve is too small, it could cause reduced flow downstream while creating back-pressure upstream. If the valve is too large, you’ll find that flow control is drastically reduced the further you move from fully open or fully closed.
When choosing the proper size, be sure to consider both the connector diameter and the overall flow rate of the valve compared to your needs. Some valves offer excellent flow while others constrict flow and increase pressure.
This means sometimes you must install a larger valve to adjust for flow than the adapter diameter alone might imply.
With sizing and design out of the way, it’s also important to consider valve end connections.
While the most obvious implication here is choosing an end connection compatible with your piping, there are also functional characteristics to common end types that might make one valve more suited to your needs than another.
Common valve connections and ends include:
Depending on your intended use, the materials with which your valves are made might be a critical aspect in ensuring safe operation and reducing maintenance and replacement costs over the life of your operation.
Stainless steel valves are excellent options in a range of processing environments, including those involving corrosive media (such as chemicals, saltwater, and acids), environments with strict sanitation standards (such as food and beverage manufacturing and pharmaceuticals), and processes involving high pressure or high temperatures.
However, if you are processing solvents, fuels, or volatile organic compounds (VOCs), choosing a valve material from a non-sparking material -- such as brass, bronze, copper, or even plastic -- is often a better option. In addition to selecting the correct body material, internal (wetted) trim parts should be evaluated for chemical compatibility as well. If your valve contains elastomers, they should also be evaluated for their chemical compatibility as well as pressure and temperature limitations.
Depending on your intended usage, you might find that valves must adhere to particular standards to meet regulatory requirements for safety, sanitation, or other concerns.
While there are too many standard organizations and potential regulations to cover in detail, common general standard organizations include:
There are also industry-specific standards to consider.
Major standards organizations by industry include:
Choosing the right valve for your project might seem complex. However, by starting with general characteristics -- such as valve design, valve size and actuation method -- you can quickly limit your options to determine the best valves for your needs.
Whether you’re designing a new processing system or looking to make upgrades to or maintain an existing system, Unified Alloys’ selection of valves and fittings can help you find the ideal solution for your application and usage environment. As a leading provider of stainless steel alloys, valves, flanges, and more, our experts have helped industries across Canada and North America for more than 4 decades. Need assistance or have a question? Contact us for personalized help.
For more Carbide Valve Ballinformation, please contact us. We will provide professional answers.
If you are interested in sending in a Guest Blogger Submission,welcome to write for us!
All Comments ( 0 )