WTA bellows sealed globe valves provide high fugitive emission protection for use in chemical processing including chlor-alkali, phosgene and fertiliser applications (Euro-Chlor approved). The valve design features a full safety sealing system enabled by multiple-walled bellows, a sealed two-piece rising stem and a stellited, conically shaped piston and seat.
Aggressive, hazardous and flammable materials are processed every day in countless plants throughout the world. In an era when environmental concerns are at an all-time high, the ability to exercise strict control over the inadvertent release of environmental pollutants, accompanied by corresponding improvements in safety, has become a non-negotiable pre-condition of a processing plant’s success.
In order to control and minimise leakage risk in critical processing applications, it is necessary to utilise high-quality valves that are capable of maintaining a tight shutoff. This is enabled by the leak resistant design of the WTA Bellows Sealed Globe Valve (BSGV).
Extensively specified and in service around the world, the WTA BSGV unites a mature design with a long service life and is virtually leak-proof to the atmosphere. The WTA BSGV satisfies all of a processing plant’s requirements and conditions pertaining to operating economy. This is particularly evident if we take a look at the actual flow and control characteristics that are facilitated by the WTA BSGV within the processing system. WTA BSGVs additionally offer the best lifetime cost option of all available valve types for demanding applications and their purchase price is insignificant compared to the cost of maintenance and processing stoppages when other valves are used instead.
The superior design of the BSGV eliminates the need for intensive or frequent maintenance. Product (medium) emissions into the environment are prevented, and in combination with the long-lasting design of WTA BSGV this adds up to a very low lifetime cost of ownership (COO).
Safety from the field
Safety design advances are founded on structural solutions that were developed from field experience and have been proven to be lastingly successful in numerous processing operations. WTA BSGVs provide the highest fugitive emission protection for use in chemical processing including chlor-alkali, phosgene and fertiliser applications. The products meet the new Euro-Chlor standard, which defines rigorous specifications for BSGVs in chlorine applications.
According to industry standards, each BSGV must meet or exceed the test parameters of EN 12266. With other designs (such as ASME valves), the DIN tests can be enhanced with tests according to API 598, depending on the application. Additional or more extensive tests like X-ray, helium, PMI, etc. are often performed at the customer’s request. They may also be carried out proactively if the application parameters are known to the testing team in advance.
Different versions available
Bellows sealed globe valves with a safety gland packing for chemical applications are available as straight, y or corner types with flanges or butt weld ends. They can be supplied in different materials like carbon steel 1.0619/WCB, stainless steel 1.4408/CF8M or low temperature carbon steel 1.6220 / LCB / LCC as well as special materials such as Hastelloy or Incoloy. Operation is also possible with pneumatic or electric actuators.
The design of the WTA BSGVs intentionally limits the stroke length while permitting a sufficient flow rate through a large diameter of the aperture. The bellows length is adjustable to satisfy force and movement requirements. The bellows diameter likewise needs to be considered when it comes to bellows performance.
No part of the medium is trapped in the valve itself as the flow is unobstructed by the inner structure of the valve (regardless of whether the valve is in the open or closed position). The packing area is completely sealed by the bellows.
Wear on the valve internals has been virtually eliminated. No soft materials such as PTFE or sealing rings are used. All internals are made of metal and a soft seat is available as an option. The very small interface between the plug and seat (called a knife edge seating system) limits wear. Compared to valves with significant rotational movements, WTA BSGVs are only min-imally affected by abrasion between the plug and seat.
The special design of a bellows system valve prevents leakage around the packing. This is especially true of the WTA BSGV, which is built using high quality materials and construction methods, with the bellows fully welded into the valve.
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