PIBIVIESSE ball valves are designed to meet the most stringent and demanding International Standards (ASME VIII, ASME B 16.34, API 6D, etc.) and, when required, the complete valve and its components can be designed and veried with any Customer requirements and with the most advanced calculation systems.
In the Trunnion mounted design configuration, the ball is supported by bearing plates, held in position by the valve closures. This configuration allows to discharge any side loads on the valve body, enabling a smoother operation of the ball, minimizing the operating torque and reducing seat seal wear.
Double o-rings, or the combination of o-rings and other type of gaskets, grant a perfect and safe sealing of the body, closures and bonnet. Thus making PIBIVIESSE’s ball valves suitable for a wide range of applications and installations (onshore, offshore, underground and subsea).
PIBIVIESSE valves are available in full or reduced Bore. Special port sizes are also available to meet all Customer requirements.
The stem seal integrity is achieved by the use of three o-rings (or a combination of different types of gaskets as required by the specification). The Stem is Anti blowout and the upper o-ring (or the graphite gasket) can be replaced with the valve in line. The ball and stem are separate components which allow a reduction of the operating torque. Stem and trunnion are supported by steel bearing sleeves with antifriction materials. Provision for grease or emergency sealant is available on request.
Independent floating, spring loaded, seats are always in contact with the ball to provide an effective tight seal even at low differential pressures. With the single piston effect design, there is an automatic body cavity release of over pressure to the line through the seat. The double piston effect design (available on request), maintains the sealing capacity of the valve even in the case of failure of the first seat barrier. Body cavity over pressure in this case can be released through a relief valve to atmosphere. A combination of double piston effect and single piston effect (dual seat design) upstream is available on request. This configuration allows a double sealing capability of the valve towards the most critical areas of the plants and still release any body cavity over pressure to the safer side. Double block and bleed operation is guaranteed with any seat design.
A stainless steel or Inconel spring between the stem and the ball or between the stem and the gland plate permits electrical continuity between all valve components.
When ball valves are to be installed below ground on buried pipelines or where not easily accessible, operators can be mounted above ground by means of suitable stem extension. Drain lines and grease injectors (if required) will be piped up to the top of the extension for an easier access.
All valves to be used in high or low temperature/cryogenic service are equipped with an extended bonnet to allow vapour space between body cavity and gland seals. This feature preserves stem seals from damages that may occur during operation at high or low/cryogenic temperatures, and allows stem seal servicing even on valves installed on insulated lines.
Butt welding ends valves can be supplied with transition pieces (PUPS) to avoid any risk of seat and seal damage during welding and post weld heat treatment operations on site.