The discharge valve is the part of an IBC most likely to cause trouble in service. A used valve that turns smoothly on the bench can still develop a slow weep after a few months.
What is happening inside
A ball valve seals against a seat ring, often PTFE. Grit from prior contents or from washing can scratch that seat. The scratches do not affect how the valve turns, but they weaken the seal over time, especially under temperature swings and the pressure of a full tote.
Why it matters
A weeping valve is a nuisance at best. At worst it means lost product, cleanup and a tote that has to be taken out of service while full. Valves are inexpensive relative to the tote.
What to ask
When requesting a reconditioned tote, ask the partner supplier whether the discharge valve and gasket were replaced or reused, and what valve type is fitted.