Bellows Seal Valve

06 May.,2024

 

Bellows Seal Valve

Bellows seal valves are valves employed in piping systems to safeguard against leakage. When selected and installed properly, they minimize the risk of potentially harmful chemicals causing injury or illness to workers and damage to the surrounding environment.

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Standard Bellows Seal Sizes

Sizes through 4”

Pressure Rating

Through ASME Class through 2500 #

Standard Forging ASME Materials

SA 105, SA 182-F22, SA 182-F91, SA 182-F92, SA 182-F316
Other materials available upon request.

Accessories

Actuators – Electric, Pneumatic or Hydraulic
Locking Devices – Open, Closed or Both
Limit Switches – Single or Dual
Stem Shroud
Position Indicator
Leak-Off Port

Bellows Seal Design Features

Conval Bellows Seal Valve vs. Packed Valves

Packed valves require two seal boundaries: a 360° seal on the stem surface and a 360° seal on the stuffing box wall. The Conval bellows seal valve removes these two leak paths. Conval bellows seal valves are used when packed valves may not reliably contain light gases or hazardous system fluids. In all applications, the 6-ply Inconel®, welded bellows stem seal is more reliable than sliding stem seals.

Zero Fugitive Emissions

Every Conval bellows assembly is tested for zero leakage using a helium gas mass spectrometer before undergoing further shell and seat leakage testing. Conval’s bellows seal emits no detectable leakage, well beyond Method 21 Fugitive Emissions Test Protocol.

No Torsion of the Bellows

A robust rising, non-rotating stem system prevents destructive torsion, providing extremely long service life from the advanced bellows design.

Three Body Styles

Conval bellows seal valves are available in Y-pattern, Angle-pattern, and T-pattern body styles.

Low Operating Torque

The manual bellows seal valve is provided with a rugged bearing system and grease fitting to minimize operating torque over the life of the valve.

Double Back-up Seating

In the full open position, Conval bellows seal valves are equipped with a superior backseat, isolating a secondary stem seal from the process fluid. The graphitic stem seal is precisely loaded by Conval’s balanced axial gland and Integral Gland Wrench (IGW), providing superb sealing to back up the bellows.

Extended Seat Life

Positive shut-off is achieved over a very long operational life due to the solid cobalt-chrome seats and discs, even in high cycle and high fluid velocity services. A cobalt-free option is available for nuclear and chemical applications.

Flexibility of Design

Conval offers a double height bellows which provides the highest bellows valve flow capacity (Cv) available per pipe size. Test ports (with lantern gland) may also be specified.

Axially-loaded Packing System

The Axial design ensures tight concentricity, which eliminates side loading of the packing and minimizes wear forces on the trim components. This feature is critical for superior valve performance.

Pressure Seal Bonnet

The simple and effective pressure seal bonnet provides ready access for servicing with no welds to cut or seal rings or gaskets to replace. The body-to-bonnet joint integrity is maintained through countless thermal cycles.

Single-piece Gland

In extreme environments, the simpler the design and the fewer the parts, the better. The durable single-piece stainless steel gland contributes to the longevity of the valve.

Pressure-Actuated Backseat

The Clampseal® pressure-actuated backseat provides maximum valve integrity by ensuring a positive internal stop for the valve stem and disc assembly. The pressure actuated backseat also extends packing life by securely isolating the packing from the pressure when the valve is fully open.

Rapid In-Line Renewability

The CLAMPSEAL® Valve is much easier to renew than anything else on the market. The CLAMPSEAL® Valve line provides a modular solution to rising maintenance expenses. Low acquisition cost is not as important as low cost over the serviceable life of a valve. Maintaining a Conval valve is far easier and much less costly than replacing a competitor’s valve.

How Do Bellows Seal Valves Work?

These valves feature an accordion like bellows—i.e., the bellows cartridge component, welded to the valve stem and bonnet. During the valve stroke the bellows compress or expand along with the sliding stem’s linear motion with little to no friction.

Types of Bellows

  • Formed bellows: Conval’s standard design, formed bellows begin as flat sheet (thin wall foil) rolled into a tube and fusion-welded longitudinally forming a single layer.  Thin metal layers are combined to form multi-ply bellows.  Mechanical or hydrostatic force forms the bellows with wide-spaced rounded folds. Conval has supplied bellows with as many as 6 plies for higher pressure applications.
  • Welded bellows: Welded bellows are manufactured by welding washer-like plates of thin metal at both their inner and outer circumferences.

Types of Bellows Seal Valves

Gate valves, globe valves and ball valves may all be supplied with Bellows should the application require.

Applications of Bellows Seal Valves

These critical components are an essential part of safe fluid system operation in a broad range of industries, including the following:

  • Aerospace
  • Biotechnology
  • Chemical processing
  • Fossil power
  • Nuclear power
  • Petroleum
  • Pharmaceutical
  • Semiconductor manufacturing
  • Vacuum and ultra-high vacuum

FAQs

Below we provide answers to some of the most frequently asked questions (FAQs) regarding bellows seal valves.

What are some advantages of using bellows seal valves?

The primary function of bellows seal valves is preventing potentially harmful or toxic fugitive emissions which can negatively affect unprotected humans and the surrounding environment. In addition to reducing the risk to employees or the environment, these valves decrease the amount of material lost during operations, which translates to lower overall material costs and greater throughput.

How do I choose a bellows seal valve?

When selecting a bellows seal valve for a system, there are several factors to keep in mind. Some of the key design considerations are:

  • The valve material chosen should be compatible with the operating conditions of the system, including the fluid media, temperature, and pressure. Common materials employed include stainless steel and nickel-based super alloys.
  • Pressure rating. The valve should be rated to handle the range of pressures and temperatures expected from the fluid system. Typical ratings range from ASME 150 to 2500 class.
  • Design Qualifications. Ensure the bellows is qualified to industry standards such as EPRI, MSS, API, or ISO.
  • The size of the valve should suit the design of the system. Conval bellows seal valves are available in sizes ranging from ¼ inch through 4 inch NPS.

How to prevent bellows seal valves from failing

Bellows seal valves are built for reliable operation. While rare, failures do occur. Generally, the root cause of the failure stems, not from the quality of the valve or bellows, but from improper selection, installation, or operation. Some guidelines for avoiding valve failure include:

  • Monitor for excessive back pressure or high inlet pressure variations
  • Select properly sized valves and bellows
  • Operate within the design pressure, temperature and stem stroke ranges.
  • Prevention of cavitation, flashing and other unusual damaging flow conditions.

Contact the Valve Experts at Conval, Inc. Today

For all your bellows seal valve needs, turn to the valve experts at Conval, Inc. Since our founding in 1967, we have developed a reputation as a premier manufacturer of high-pressure/temperature, forged steel valves suitable for use in the most demanding severe service applications. Our commitment to quality translates to our products’ superior durability and performance at the lowest life-cycle cost in the industry.

For additional information about our valve offerings or assistance specifying one (or hopefully many) for your application, contact us today.

The Ultimate Guide to Bellow Globe Valve

Looking for a comprehensive guide to bellow globe valves? Look no further! Our guide covers everything you need to know about this type of valve, including its design, features, advantages, and applications. Whether you’re a beginner or an experienced professional, our guide is the ultimate resource for understanding bellow globe valves and how they can be used in various industries.

Bellow globe valves are an innovative type of valve with outstanding sealing performance, featuring flexible metal bellows that seal leak-free while protecting its stem against corrosion. As a result, this type of valve makes an excellent solution for pipelines carrying hazardous or flammable substances at elevated temperatures as well as where system media requires heating up significantly.

Let’s take a detailed review of the bellow globe valves.

What is a Bellow Globe Valve? 

A bellow globe valve is a type of valve that is designed to regulate or control the flow of fluids through a pipeline. It consists of a globe-shaped body, a bellow seal, and a stem that is attached to a disc or plug. The bellow seal is a flexible component that is designed to provide a seal around the stem, preventing fluid from leaking out of the valve.

A bellow globe valve is a type of pipe valve with an internal bellows seal for leakproof protection and to protect its stem from corrosion, prolonging its lifespan.

Bellow globe valves come in various sizes and materials for different applications; selecting one that best meets your requirements is key to meeting them successfully.

Types of Bellow Globe Valve

There are different kinds of bellow globe valves. They are typically divided by body type, material of construction, number of seats, and method of activation.

Globe valves consist of a bonnet, body, stem, seat, and disc or plug, all connected together with vertically moving stems to open or close them.

Forged Bellows

Bellow globe valves are specially designed valves used in industries where leakage risk is high. Such industries include nuclear power plants, chemical facilities, water treatment services, and petroleum companies – among others.

A forged bellow globe valve employs a metal bellow as a seal against stem leakage, offering a double seal system that helps eliminate leakage risk while adding safety measures for the medium being transported through it.

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Welded Bellows

Welded bellows are manufactured using various forms of ductile metal and can come in an assortment of sizes and alloy types designed to withstand various harsh environments.

These welded bellows are often employed in applications requiring flexible sealing solutions due to their ability to flex in multiple directions and accommodate various pressure and temperature levels. Furthermore, various spring rates are available so as to meet different levels of pressure or temperature.

Metal Bellows

Metal bellows have many industrial and mechanical applications. These precision parts can absorb thermal expansion, vibrations, and movements to keep equipment functioning effectively.

Welded bellows are an extremely precise form of precision metallurgy that can be constructed using various exotic materials. Their advantage lies in their superior tensile strength, resistance to nicks and dents, as well as greater flexibility than formed bellows.

Rubber Bellows

Rubber bellows are flexible seals used to protect mechanical structures from the environment while still permitting movement. They’re commonly found in industries like industry and transportation.

Molded bellows can be created using various materials, including natural rubber and Neoprene(r). Each provides different levels of oil-, flame- and sunlight/ozone resistance.

Application of bellow globe valve in points

Bellows globe valves are widely used in many industries and applications due to their ability to provide a high degree of sealing and reliability. Some common applications of bellow globe valves include:

  • Chemical processing
  • Food and beverage
  • HVAC systems
  • Petrochemical industry
  • Pharmaceuticals
  • Power plants
  • Water treatment

Working principles of bellow globe valve

  • Bellow globe valves use bellows to create a seal around the valve stem, preventing fluid from leaking.
  • When the valve is opened, the stem rises and moves the disc or plug away from the valve seat, allowing fluid to flow through the valve.
  • To close the valve, the stem is turned or pushed downward, and the disc or plug is forced against the valve seat, blocking the flow of fluid.
  • The bellows are located around the valve stem and expand or contract as the stem moves up and down, maintaining a seal that prevents fluid from leaking through the valve.
  • The movement of the stem is typically controlled by a handwheel or actuator, allowing for precise control of the flow rate.

Advantages and Features of Bellow Globe Valve

Bellow globe valves are widely used in industries across many disciplines to regulate fluid flows.

These valves are an ideal way to handle hazardous media without risking leakage, which could prove potentially hazardous both to workers and the environment.

Cost-effectiveness

Bellow globe valves offer an economical solution for industries with complex fluid transport needs. Not only are they durable and require little upkeep, but they’re also an economical way of protecting sensitive fluids, such as toxic ones, from spillage or leakage.

Durability

Bellow globe valves are highly sought-after due to their durable construction and reliable operation, plus low maintenance needs, which help lower operating costs while also cutting downtime and downtime costs.

Additionally, these containers can withstand high temperatures and pressures – making them suitable for transporting corrosive, toxic, or dangerous liquids.

Ease of installation

Bellow globe valves are industrial valves used to regulate fluid flows within systems. They come in an assortment of sizes and materials with various pressure ratings for easier control.

Bellow globe valves boast numerous benefits and features that make them attractive, such as no leakage, corrosion resistance, and maintenance-free operation. Furthermore, these valves can control multiple processes and fluids efficiently – features that make them a popular choice across many industries.

Safety

Safety is of utmost importance in many industries, and bellow globe valves were created with this in mind. Able to withstand high temperatures and pressures, making them suitable for various applications, these bellow globe valves indicate that safety must always come first.

Safety benefits of pollution monitoring systems include preventing harmful emissions and eliminating leakage risks from fluid pipelines while simultaneously decreasing material losses during operations and increasing throughput.

Flexible

Bellow globe valves differ from regular valves by featuring flexible metal bellows that provide a leakproof seal and protect their stem from corrosion, helping ensure a smooth operation and prevent damage to the valve itself. This feature ensures damage-free use.

Based on their application, regulators can be constructed from various materials. For instance, stainless steel is often utilized to regulate corrosive fluids at higher temperatures and pressures, while plastic regulators provide an easy installation and maintenance experience while being suitable for hazardous or explosive environments.

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XINTAI Valves is an industrial valve manufacturer offering an assortment of ball, gate, butterfly, check, and safety valves in various styles and sizes.

XINTAI Valves boasts an international network of distributors and suppliers to quickly provide customers with the products they require. Furthermore, their expert engineers can assist in selecting the ideal valve type for each application.

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