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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Sizes through 4”
Through ASME Class through 2500 #
SA 105, SA 182-F22, SA 182-F91, SA 182-F92, SA 182-F316
Other materials available upon request.
Actuators – Electric, Pneumatic or Hydraulic
Locking Devices – Open, Closed or Both
Limit Switches – Single or Dual
Stem Shroud
Position Indicator
Leak-Off Port
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.
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.
A robust rising, non-rotating stem system prevents destructive torsion, providing extremely long service life from the advanced bellows design.
Conval bellows seal valves are available in Y-pattern, Angle-pattern, and T-pattern body styles.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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Gate valves, globe valves and ball valves may all be supplied with Bellows should the application require.
These critical components are an essential part of safe fluid system operation in a broad range of industries, including the following:
Below we provide answers to some of the most frequently asked questions (FAQs) regarding 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.
When selecting a bellows seal valve for a system, there are several factors to keep in mind. Some of the key design considerations are:
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:
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.
A bellow seal valve is a control valve that does not have traditional gland packing and instead has a bellow cartridge that is welded to the valve’s bonnet and stem. Because it may be bent in compression or extension, the bellow is similar to a coiled spring. The main difference between a bellow seal valve and a globe valve is that a globe valve has gland packing along the stem, while a bellow seal valve uses bellows instead of packing to prevent leakage. These valves are completely leakproof and capable of handling caustic substances. These valves may be found in the butadiene extraction unit.
The majority of control valves are used to regulate the flow and pressure of process fluid. As a result, the risks of leakage are quite significant; leakage might result in material loss. The substance might be radioactive or chemical, causing several difficulties at a facility. The fluid utilized may be caustic, explosive, or toxic. So, to remedy this issue, we may utilize the seal valve.
A bellow-sealed valve may be fitted in any position, however, it should not be installed with the stem upside down. So, by installing a bellow seal valve, we can avoid the collection of debris in the bellows region. So, before we install the bellow valves, we must check that the pipes and valves are clean. The pipes must be linked in such a manner that there is no unnecessary stress acting on the valve housing.
The valve body material must be chosen based on the flow media’s pressure, temperature, corrosive, and erosive properties. The bellow cartridge will be welded; there are numerous convolutions in a bellow cartridge, and these convolutions may be squeezed or extended in response to valve stem movement. The bellow’s construction material would be stainless steel with titanium added to it, allowing the bellow to endure extreme temperatures.
A Bellows globe seal valve is distinguished by its use of metal bellows. Bellows are classified into two types:
For both formed and welded-leaf bellows, the amount of movement in each fold is the same. As a result, mechanically produced bellows are two to three times longer than welded leaf equivalents at the same stroke rate.
The lower end and stem assembly are welded by automated seam welding, while the connecting plate is welded by automated seam welding, forming a metal shield between the fluid medium and the environment and assuring zero leakage from the valve stem.
The sealing surface of the valve disc and the valve structure is perfectly ground so that once installed, it is certified that it has 100% passed a pressure test and any risk of leaking is avoided. The stuffing box is constantly retained on the bellows as an auxiliary seal, which increases durability and protection. The metal bellows of the high-pressure valves are multi-layered, ensuring an open/close life of 10000 times at maximum pressure via hydroforming.
A Bellows Seal Globe Valve is a kind of control valve with a compact construction that employs bellows to seal the valve stem components. The bellows valve has a bellow, and the lower end of the stainless-steel bellows is welded to the stem to prevent system fluid from eroding the stem. The other end is inserted between the valve’s body and its cover to form a permanent seal. This double-seal construction prevents leakage since the stem packing prevents additional leaking even if the bellows collapse. The bellows are welded to the valve stem to maintain constant working efficiency and to avoid valve stem vibration caused by valve insert movement.
The Bellows Seal Globe Valve’s distinctive design and efficiency in providing leak-proof operations make it the best-suited valve for a broad variety of applications, particularly hazardous compounds and when system media is at high temperatures. Bellows valves have the extra advantage of being durable, maintenance-free, and cost-effective. GMK Valve is a professional bellow seal valve manufacturer; please contact us if you have any questions.
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