Gate Valve FAQs

Wedge gate valves are designed for isolation duty, left in either fully open or fully closed positions.

Using a gate valve to regulate flow will likely cause damage to the seats and/or wedge. Other valve types are more suited to flow regulation, such as our range of control valves.

T-T's swing check valves work to a maximum operating pressure of 16 bar.

Knife gate valves are suited to isolating fluid networks with higher concentrations of suspended solids such as wastewater and slurries.

A multiturn gate valve is designed to isolate the flow but means of a wedge that travels through the media.  When fully open a gate valve offers an unobstructed clean bore.  A quarter turn butterfly valve is designed to isolate or regulate the flow by means of a rotating disc in the flow path.  As such the butterfly valves are designed for clean medias.

The main difference between Non-Rising Stem (NRS) and Outside Screw and Yoke (OS&Y) gate valves is how the stem moves to operate the valve.

• NRS gate valves - the stem does not rise or extend above the valve body when operating, instead rotating to move the gate up/down inside the valve body while the stem remains in full contact with the media.
• OS&Y gate valves - the stem rises/extends to move in/out of the valve body when operating, this raises or lowers the gate inside of the valve body.

• Cast iron is an alloy containing 96%-98% iron, 2%-4% carbon, and small amounts of silicone - it can withstand high temperatures and pressure ratings but has no flexibility.
• Ductile iron is a created by the addition of magnesium alloy to molten iron, resulting in an iron that has improved strength, corrosion resistance and flexibility.

T-T offer gate valves are designed to BS5163/EN1074 for either water or wastewater duties up to 70C and maximum velocity of 3m/s.  Resilient gate valves are suited to clean and neutral fluids, while metal seat gate valves are suited to sewage and wastewater duties.   For duties beyond these constraints please contact us. 

Gate valves are not recommended for use at the end of a pipeline (end of line duty) because they are not designed to handle the higher pressure and flow conditions that can occur at the end of a pipeline.

Suitability rated blanking flanges are recommended - a type of flange that is used to block off and prevent any flow through the end of a pipeline.

A range of gate valve operating elements are available, ranging from a manual handwheel or stem cap that allows for remote operation via a T-key or extension spindle.

For automatic operation, intelligent actuators can be fitted.