Severe Service & Dirty Service
October 10th, 2018 by Amanda Schumann
Quarter Turn Ball Valves
Global Supply Line’s manufacturers and Australian Pipeline Valve can supply unique alternatives to conventional ball valves. The problem with conventional ball valves whether they be soft seated or metal seated is that their life is reduced by the fact that entrained particulates/debris are scrapped across the ball through the full 90º motion of the ball, this also significantly increases the torque requiring a larger actuator and can cause sticking and jamming. In addition this increases the likelihood of damage to the seating area and also eventually damages even the hardest coatings.
The only part of the ball that seats in the open and close position is the final section that contacts the seat around the edge of the ball. The rest of the ball doesn’t do anything. Consequently, there are many valves on the market that effectively reduce or do away with the rest of the ball. This also reduces the ‘running torque’, which can be a problem with larger actuators that have a low running torque torque compared to the open and close strokes. There are many valves on the market that we can offer that achieve this objective.
All the following options are available in metal-to-metal seating and soft seated. Furthermore, harder seats like PEEK can be utilised to increase the life of the seat. Alternatively, seat inserts such as PTFE, offer memory and resilience as a way of reducing seat damage depending on the pressure rating and the nature of the particulates.
The first option is to supply a ball that has scalloped or fluted veins on the ball. These act as channels to direct the debris away from the contact area during the turning motion and therefore drastically reduce the amount of wear and tear on the seating surfaces throughout the 90º turn process. This style of ball also is combined with a higher degree angle wedged seating area that scraps off debris more effectively and can be combined with a metal to metal seating arrangement to further increase the life of the valve.
Of course the next logical progression is to use a non-spherical non contacting ‘core’ rather than a ball. Then mount the seats on the core itself so the seats can be cheaply and quickly replaced but more importantly it has a longer life, especially when combined with protective seat scrapers. This is where we can offer the old Mapegaz design, which essentially has a non contact steel core, which only purpose is to hold the seating edges. This of course also saves money as it does not require a full stainless steel/hard faced ball, as only the contact faces need to be hard surfaced. This is a time proven valve and is used successfully in many dirty service applications. Of course, the Orbit principle which APV can also offer uses the same logic but in the case of the orbit it only has a single seat and is more costly to be actuated as it is not a quarter turn operation.
Then there are other designs that take this even further once again using the Orbit lift off seat principle but on a quarter turn ball valve. The actual lift off/cam action seat ensurers there is minimal wear during the turning motion. We can also supply top entry full port circular plug valves greased or ungreased that can often be more cost effective and or easier, cheaper, quicker to maintain than to service with soft or metal or bronze sacrificial seats that can quickly and cheaply be replaced in line.
Please refer to the APV ball special catalogue for information on some of the valves that APV can offer click here. GSL can also offer many other manufacturers that supply valves in this area that are more competitive and a longer lasting solution than even traditional metal to metal seated ball valves.
Also see my other articles on the full range of Abrasive, Dirty, Slurry, High Temperature and Special Service Valves that GSL & APV can provide click here, Dirty Abrasive Service Quarter Turn Oil & Gas Valves click here, and for my article on Seating Systems for Abrasive & Dirty Service click here.
Options shown on this post are numerous but include ball valves with triple seat inserts:- a hard wiper which protects a hard class V seat insert which protects a final softer leak tight insert.