Pump row — Inzonex Modular Insulation, hot-water skid
Ball valves / Maintenance
Ball valve maintenance
The valve you have never turned is the one that will not turn.
A ball valve has almost nothing to maintain and one thing to do: turn it. Valves left in one position for years pick up deposit around the ball and stiffen. The moment anyone needs them is a shutdown, which is the worst moment to find out. Everything else here follows from that.
Exercising
What preventive maintenance is here
Turn them on a schedule
Full travel, closed and open again, on the same cycle as the rest of the plant inspection. It breaks up deposit at the seat before it sets. It also shows which valves are stiffening, while there is still time to act on it.
The ones nobody turns
Drain valves, vent valves and the isolating valves around standby plant. They are the ones relied on in an emergency and the ones that have stood longest, which is exactly the wrong combination.
The gland
The one adjustable part
What it is
A packing around the stem, held by a nut or a gland follower, sealing where the stem passes out of the body. It is the only part of an ordinary ball valve that is meant to be adjusted in service.
Adjusting it
Take up a weep at the stem by tightening the gland nut a little at a time. Check that the valve still turns after each step. Pulled down hard, the valve becomes stiff enough that somebody forces it, and forcing it is how stems get bent.
When adjusting stops working
Packing has a life. Once it will not seal without being tightened to the point of seizing, repack it or replace the valve. A three-piece body comes out without disturbing the pipe.
Leaks
Telling them apart
At the stem
The gland. Visible, adjustable, and the least serious of the three.
Past the ball
The seat, and it shows as the valve failing to hold when it is shut rather than as a drip. Usual causes are debris across the seat, or wear from a valve that has been left part open.
At the body joint or the flanges
A gasket, treated like any other flanged joint - even bolt-up, re-torqued warm.
Access
What has to stay reachable
The lever has to swing
A quarter turn needs the arc kept clear. Insulation wrapped around a lever survives until the first isolation. Then somebody cuts it away and never refits it, and the valve runs bare for the rest of its life.
The gland nut has to be reachable
Otherwise a weep at the stem becomes a reason to strip the covering off instead of a two-minute adjustment.
The lever also reports the state
Along the pipe is open, across is shut. Covering the lever removes the only indication the valve gives, and someone will eventually work on the wrong side of it.
Reference
Fault against action
| Fault | Usual cause | What to do |
|---|---|---|
| Stiff or seized | Deposit at the seat after standing | Exercise on a schedule; do not lever it |
| Weeping at the stem | Gland packing relaxed | Tighten a little at a time, check it still turns |
| Will not hold when shut | Debris or a worn seat | Cycle it fully; replace if it still passes |
| Leaking at the body joint | Gasket | Even bolt-up, re-torque warm |
Fault · Usual cause · What to do
Asked about ball valve maintenance
Questions.
Answers distinguish modelled heat-loss estimates from equipment selection and service guidance.
Why do ball valves seize?
Because they are never turned. Deposit builds around the ball while the valve stands in one position and sets there. Exercise them through full travel, on the same cycle as the rest of the plant inspection. That is the preventive maintenance on them, and it finds the stiff ones before an emergency does.
How do you fix a ball valve leaking at the stem?
The gland. Tighten the nut a little at a time, checking after each step that the valve still turns freely. It may only seal when pulled down hard enough to make the valve stiff. The packing has then reached the end of its life, so repack the valve or replace it.
My ball valve will not hold when it is closed. Why?
The seat, rather than the gland. Either debris is lying across it, and cycling the valve fully a few times may clear that. Or the seat is worn. Wear usually comes from leaving the valve part open, which concentrates flow at one edge of the ball.
How often should ball valves be exercised?
On the same cycle as the rest of the plant inspection, and full travel each time. The valves that most need it are the ones nobody thinks about: drains, vents and the isolation around standby plant. Those have stood the longest, and they are the ones relied on in an emergency.
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More on ball valves
The node page carries the heat-loss figures and the size table.