Rising stem or non-rising stem gate valves are the two categories. The stem is referred described as “rising” if it does so as the valve is opened and protrudes through the valve bonnet. Regardless of the valve position, “non-rising” describes a stem that does not rise from the valve bonnet. Disc and stem are both removed from the flow channel by rising stem designs when the valve is open. When the valve is open, non-rising stem designs often leave the stem in the flow channel, however, it is also feasible to entirely house the stem inside the disc. In corrosive environments, such as sea spray, where it is not ideal to have the stem permanently exposed when the valve is open, non-rising stem gate valves are preferable in Saudi Arabia.
The non-rising valve, on the other hand, might not be the best option if the flowing medium is corrosive since the stem is still in the flow path when the valve is open. There is little chance of dirt or foreign objects harming the packaging or getting into the system since non-rising stems spin within the packaging but do not move vertically. Non-rising valves nearly always include a local visual marker that shows where the valve is located. If a rapid local visual indication is required, the rising stem design is ideal (it is easy to identify if the valve is open or closed with the rising stem design).