Seat valves

Seat valves are also referred to as globe valves. The flow typically passes under the shut-off cone (shut-off gate). When the valve is closed, the cone is sealed against a metal shut-off surface. When the valve is opened, the flow around the cone is discharged 360°, for which reason a seat valve with the correct cone options is excellent for control applications.

The term ‘globe valve’ derives from the round shape of the valve body. ’Straight through’ is the most common type of seat valve, where the flow makes two 90° turns. There are also ‘Y-pattern’ valves used if smaller pressure losses are required, for example, in hot oil systems. ’Angle pattern’ seat valves are used if the angle between the inlet flange and outlet flange needs to be 90°.

Seat valves are available for different applications: shut-off valve, control valve, emergency shut-off valve, shut-off check valve, drain valve, pressure relief valve, etc. A hand wheel-operated seat valve opens slowly, thereby avoiding harmful pressure shocks. In contrast, a spring-actuated emergency shut-off valve can be closed in less than 0.15 seconds, if necessary.

The availability of various material options renders seat valves suitable for widely different media. However, it must be considered that due to their structure, seat valves prevent pipe cleaning by means of pigging. The seat valve structure also causes some pressure loss. If the pressure losses from a straight through or T-type seat valves is excessive, angle seat valves characterised by a smaller pressure loss can be recommended.

In addition to gland seals, bellows seals are available for seat valves as a double backup to prevent valve stem leaks and emissions. This is an excellent option considering valve maintenance needs and usability in case of hazardous media, such as hot oil, chlorine, or alkyls. The bellows prevent medium from reaching the gland for improved environmental friendliness and safety. A collar nut in the neck part allows the vertical movement of the stem (instead of rotation as in the case of gland seals); owing to this, valve threads are protected against external contamination and corrosion.

Our seat valve range is quite extensive; it consists of products by different manufacturers. ARI Armaturen produces so-called conventional seat valves up to the nominal size DN 500. Descote is a valve manufacturer specialised in particularly demanding process media, such as chlorine. The KÜHME product range includes control and emergency shut-off valves.