Double seat valves (DSV) are a legacy of the last century. The utilization of complete pressure relief while accepting bad leakage at the same time is no longer appropriate. All the less so as today's company standards and legal requirements for a minimally acceptable leakage are constantly increasing. For DSV, this results in manufacturing tolerances that can hardly be measured, let alone produced at reasonable cost. If then aspects such as thermal expansion come into play, physical limits would have to be crossed.
Replacing DSV is not as easy as it may seem at first glance. Due to the second seat the maximum flowrate is approximately 125 % of a standard globe valve. Replacement would therefore cause considerable work on the piping around the valve and risk unforeseen problems.
VETEC rotary plug valves offer a perfect solution here. Their high flow rate allows the DSV to be replaced without work on the piping (CAPEX optimization). Even high nominal as well as differential pressures are no problem. An example of several NPS 8 – CL 2500 valves are shown in the image below.
With its proven in use design, they ensure safe and reliable plant operation over the next decades, resulting in low OPEX.