Seat material selection in ball valves poses a challenge to most end users in the industry. This is because most users are masters of their domain but lack the technical information to make the correct seat material selection. In this blog, we shall present the required information to help such users.
Generally, PTFE (Poly tetra fluoro ethylene) is the most common seat material used in ball valves. This is because PTFE is chemically compatible with most chemicals and has a very low co-efficient of friction. This allows ball valves to be operated with ease. PTFE can work at 69 Kg/ sq. cm in the temperature range -40 deg C to 90 deg C. The maximum temperature this seat material can withstand is 200 deg C at pressures up to 15 Kg/ sq. cm.
For higher temperatures up to 250 deg C and pressures up to 15 Kg/ sq. cm, Carbon Filled PTFE grades can be used. Similarly, Glass-filled PTFE grades can be used for higher pressures up to 100 Kg/ sq. cm at room temperature.
In case of valves for hydraulic applications at room temperature and pressures up to 400 Kg/ sq. cm, POM (Acetal Resin) seats can be used economically.
In applications requiring the seat material to withstand both higher temperatures (150 deg C) and pressures up to 400 Kg/ sq. cm, PEEK seats can be used. Virgin PEEK, as well as carbon filled PEEK grades, are available. However, PEEK seats are very expensive and should be specified only in very critical applications.
For severe service, valves can be supplied with metal seats. Various combination of metal seat types are available for temperature ranges from 350 deg. C to 650 deg C. The advantage of metal seats is that there is practically no pressure constraints. Moreover, these valves can work very well with abrasive media.
KAVAATA valves are manufactured with all the above-mentioned seat materials and can be supplied against specific customer requirements. KAVAATA can supply metal seated valves with Class V and Class VI leakage rates.