AS-Schneider is among the world's leading manufacturers of Instrumentation and Double Block&Bleed Valves with approximately 350 employees.
With an international network made up of our subsidiaries and partners in more than 20 countries, we ensure that our customers receive the engineering know-how from AS-Schneider worldwide.
Our customers benefit from suitable solutions which are distinguished by efficiency, longevity and technological progress - convince yourself!
AS-Schneider is one of the World's Leading Manufacturers of Instrumentation and Double Block & Bleed Valves. Our Valves are mainly used for pressure and differential pressure measurement in all fields of plant construction: - Conventional Power Plants (oil, coal, gas), Nuclear Power Plants - Onshore and Offshore Production, Chemical and Petrochemical Industry, Refineries - Steel Mills, Cement Plants, Waste Incineration Plants, Sea Water Desalination Plants, Flue Gas Desulphurization Plants - Natuaral Gas Production, Processing or Transport and Storage. AS-Schneider Valves are also available for special services: Fire Safe Tested and certified, Fugitive Emission Applications and Oxygen service. Exotic alloys are common practice for AS-Schneider.
These Industrial Valves are mainly used for pressure and differential pressure measurement in all fields of plant construction:
With the Taurus Series, AS-Schneider presents a Series of Double Block & Bleed Pipeline Ball Valves, designed specifically for your application in the oil and gas industry. The valves are not only impressive with their sophisticated technology, but also with their unique and well-thought-out design.
The AS-Schneider Process to Instrument Valves such as Monoflanges & VariAS-Blocks are designed to overcome the problems of traditional assemblies on primary isolation duties. By combining piping & instrument valves in a single assembly, they provide weight & space savings, along with other benefits including reduced potential leak points & safer hook-up. This more compact & efficient arrangement reduces not only pipework vibrations & associated stress but also installation & maintenance costs.
AS-Schneider is one of the World's Leading Manufacturers of Instrumentation Valves & Manifolds. We offer a large variety of E Series Valves & Manifolds as well as numerous accessories needed for the instrumentation installation globally. Many of our valves are available from stock or within a short period of time.
Available for special services: Fire Safe Tested and certified, Fugitive Emission Applications & Oxygen service. Exotic alloys are common practice for AS-Schneider.
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Does tightness contradict a smooth actuating torque?
In order to be able to give an answer, the functional principle of a ball valve have to be explained briefly: A relatively low contact force is sufficient to ensure the tightness of the ball to the ball seat, as the contact force is automatically increased with increasing pressure due to the design principle. However, in order to ensure the tightness of the ball seats towards the body, high forces are required for high pressures in order to compress the graphite seal accordingly. These forces are often applied by a screw connector or when assembling the ball valve body (for example a three piece body).
In a conventional design, the compression force for the graphite seals on the ball seat towards the body is applied directly via the ball, which also increases the contact pressure of the ball seat on the ball as the seal is compressed. This increased contact force has a negative effect on the actuating torque. The ball runs very heavy. Therefore many manufacturers limit their metal seated ball valves to a max. allowable pressure of 100 bar - because that is the limit that still permits actuation of the valve.
If the applied force is reduced, actuation becomes easier, but then the compression of the graphite seal on the seat retainer is not sufficient to seal up to 420 bar reliably. Leakage occurs around the ball seat.
So what now? This problem has not let go of the development team of AS-Schneider. They started looking for a solution and developed the 'Dissolution' ball valve design. The patented design offers optimum distribution of forces and loads in the ball valve, so that they only occur where they are actually needed. This means that the ball valve can be actuated easily even under high pressures up to 420 bar.
How it works - 'Dissolution' ball valve design
The forces needed to maintain the tightness between ball seat and valve body are only directed onto the corresponding graphite seal rings. The ball is only spring-loaded, which ensure a low, defined, minimum pressure off the balls on the ball seat. The operating torque can thus be significantly reduced, allowing the operator to operate the ball valve easily. At the same time, this construction offers maximum tightness and long service life.
Unauthorized access or accidental operation can quickly have disastrous consequences. However, system operators can easily prevent both scenarios:
The anti-tamper valve head unit is equipped with a special Anti-Tamper Key (AT-Key), which fits exactly in the key guide. The valve can therefore only be operated with the AT-Key. In addition to this safety function, installing a padlock prevents the AT-Key being inserted into the key guide. Operating the valve is therefore no longer possible which protects your equipment against unauthorized opening and closing of the valve head units. The valve can be locked reliably in every position required.
The valves can also be equipped with a Stainless Steel Handwheel and an additional fitted locking plate. This design allows minimum handle movements and is ideal as protection against unauthorised closing of the valve.
In pipelines, very diverse media with varying properties can be transported. The problem: Many of these media expand when heated, like, for example, liquefied natural gas. If the medium cannot expand because it is trapped in a fixed space, the pressure increases instead. If the liquefied natural gas is spatially blocked at -161 degrees Celsius and 1 bar pressure and the temperature is allowed to rise to room temperature, the pressure increases to 1,895 bar.
Therefore, it must be ensured that areas, in which the medium can be blocked, are protected against a pressure overload. The decisive factor is: According to the standard, the overpressure must not escape into the atmosphere, but must be released into the process line. Both the Double Block & Bleed Piping Ball Valves of the Taurus Series and the "Process-to-Instrument" ball valves of the VariAS-Block Series meet these requirements as a standard feature. They consist of two block ball valves and a bleed valve (Double Block and Bleed). Depending on the version, they can withstand pressures up to 420 bar.
Different standards require diverse solutions
Among other things, AS-Schneider's solutions are designed for the two diverging standards EEMUA 182 and SHELL MESC SPE 77/170. The latter requires venting through a three-millimeter borehole in the ball in the direction of the process. This technique is used in the VariAS-Block Series.
Pressure escapes through three-millimeter borehole
The ball valves are available with Floating Ball Design. The ball seats are fixed and the ball can move in closed position in direction of flow. When the valve closes, the ball also rotates and the liquid or gas enters in and around the ball. Without the three-millimeter borehole, the medium would be blocked between the two ball seats which would lead to a significant increase in pressure when heated. The medium can simply expand to the process when heated without the pressure rising through the three- millimeter connection borehole to the process side.
On top of that, there are ball valves with Trunnion Ball Design. In this application the balls are fixed in the direction of flow but the valve seats can move.
Self-venting valve seats
With the EEMUA 182 standard, venting must not take place via a borehole in the ball, but must be automatic. For this purpose, for example, self-venting valve seats are used, which are pressed against the ball by means of spring force. The medium flows into the space around the ball. Here, too, the medium is initially blocked between the two ball seats and when heated, the pressure increases. In this case, however, due to the rising pressure, the valve seats are pushed away from the ball against the spring force, whereby the pressure can escape. The advantage over the venting with the three-millimeter borehole:
The solution works bidirectionally, that is, it seals in both directions. This solution also works very reliably.
There are also self-venting ball seats designed according to the above-described Floating Ball principle, which can be bidirectionally sealed. Here, the venting of the trapped pressure takes place around the valve seat. However, the pressure at which the medium begins to flow past the valve seats cannot be accurately predicted here, since it depends greatly on the manufacturing tolerances. Therefore, solutions with the three-millimeter borehole in the ball are, in many cases, the more suitable option, as they work very reliably and are wear-resistant despite the borehole.