Gate valve vs ball valve: which one to choose for a pipeline
Gate valves and ball valves both isolate a line: fully open or fully closed. Their designs are different, and on the same pipeline one may last twenty years while the other fails in three. This guide sets out how to choose.
TAZ Engineering Team · · 7 min
How they work
In a gate valve a wedge or a pair of discs moves across the flow on a threaded stem. Closing a DN 300 gate valve takes dozens of handwheel turns. In a ball valve a bored ball rotates 90 degrees, so the valve closes in a quarter turn.
This explains the practical differences: a ball valve closes fast and needs space for the lever or gearbox, a rising-stem gate valve closes slowly and needs headroom for the stem.
Tightness and temperature
A ball valve with PTFE seats gives near-zero seat leakage but is limited in temperature, usually 150–200 °C depending on the seat material. Metal-seated gate valves work on steam and hot water up to 425 °C and beyond with the right steel, but their tightness depends on the quality of seat lapping.
For water up to about 70 °C, resilient-seated gate valves reach rate A tightness at low cost.
Size, weight and cost at large diameters
Up to DN 100–150 a ball valve is usually more compact. From DN 300 upwards a full-bore ball valve becomes very heavy and expensive, while a gate valve, especially a cast-iron resilient-seated one for water, stays economical. That is why large water mains and district-heating networks still use gate valves, with ball valves on branches and gas lines.
Water hammer and closing speed
Closing a ball valve quickly on a long water main can cause water hammer. A gate valve closes slowly, which is an advantage at pumping stations. Large ball valves on water service are normally fitted with a gearbox to slow the stroke.
Maintenance
A gate valve can be repacked and, in many designs, its seats can be lapped on site. A fully welded ball valve cannot be serviced and is cut out when it fails; flanged split-body ball valves can be repaired with seat kits.
Neither type should throttle flow. A partly open gate valve erodes its seats; standard ball valves are also isolation valves only.
Quick rule of thumb
Gate valve: large DN, water and steam, high temperature, slow closure, on-site repair. Ball valve: gas, small and medium DN, fast shut-off, minimal leakage, buried service with fully welded designs.
Send the medium, DN, PN and temperature and the TAZ engineering team will recommend a valve type.
Checklist
- service medium
- temperature
- DN and PN
- need for fast shut-off
- water hammer risk
- installation space
- required leakage rate
- maintainability