Seat Valves

Seat valves are also referred to as stop valves and 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°, therefore 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 valves, 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°.

In steam and condensate applications, seat valves have several advantages, which include temperature and pressure resistance, since there are no soft seals inside the valve. Slow operation (as compared to ball valves) reduces the impact of water hammer. In addition, the valve can be customised for various applications: shut-off valve, control valve, shut-off check valve, drain valve, pressure relief valve, etc.

In addition to gland seals, bellows seals are available for seat valves as a double backup to prevent valve stem leaks. This is an excellent option considering valve maintenance needs and usability. Bellows keep the gland free of pressure, therefore the gland does not need be tightened. A collar nut in the neck part allows 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.

The ARI Armaturen range also includes the ARI-FABA®-SUPRA I model for more demanding conditions. In the case of this valve, the bellows is protected against pressure shocks to ensure a longer service life. The valve is used, inter alia, under vacuum conditions, where the valve sealing solutions prevent leaks into the process. This is of special importance in condenser valves.

Our seat valve range is extensive; it consists of products by different manufacturers. The best known of these, ARI Armaturen, produces the so-called conventional seat valves up to the nominal size DN 500.

All valves are available both as manually operated versions and as actuator operated (pneumatic and electrical) versions, and they can be applied for both on/off and control operations. ASME connections are also included in our range.

Listen to and watch our webinar Seat valves: from gland to bellows.