Weld Area

Weld-in-place ball valves

VW India & ME recently heard of an elegant solution that can save time and money when welding soft-seated ball valves. Rafay Bin Monsoor was kind enough to explain more.
 
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Article by David Sear
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Rafay, people have been welding ball valves into piping systems and pipelines for decades. So all challenges have long been resolved, right?

Far from it! If you weld floating ball valves to a pipe, you must always take into account the possibility of heat transfer from the weld area to the valve itself. That can cause damage to the soft internal components such as the seats. For many years the industry practice has therefore been to disassemble the valve, weld it to the pipe and then reassemble. This is also being done for actuated valves. That’s fine if you have properly trained and certified personnel at hand. In practice, disassembly and subsequent reassembly is often left to plant personnel who for the most part are not valve automation experts and most often do not, or cannot, calibrate the reassembled automation components properly. This can result in a malfunctioning valve which, to compound the issue, is probably no longer covered by the supplier’s warranty.

Is there a solution?

One way is of course to modify the weld procedure, but the question is whether that message will properly trickle down to the field teams responsible for installation. Another is to specify valves with pup-pieces or extended end caps. This moves the weld area away from the valves, hence reducing the risk of heat transfer to the soft internal components. What we have done is to take a fresh look at this issue and have developed a properly engineered solution. Our ‘weld-in-place’ ball valves are therefore fitted with extended end caps that have heat sink rings with a series of radiator-type grooves cast into the outside diameter. This creates increased surface area, allowing more heat to dissipate during welding, protecting the valve seat materials from damaging heat transfer.

Sounds simple…

Simple, inexpensive but very effective! And I can tell you that this technology has been proven in many installations for many years. Yet time and again I am surprised how many people have not yet heard of the ‘weld-in-place’ concept. Still, when I make people aware of the time and cost savings associated with this option they quickly become very enthusiastic.
 

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