ACT · Act now — correcting soonShale shaker →Cost of fault ≈ $90k+ / incident
Why it matters
Overflow sends unscreened whole mud straight to the active system, defeating the entire solids-control train at stage one. It often signals total flow exceeding deck capacity, a maldistributed feed, or screens far too fine for the rate.
Likely causes
Flow-distribution box / gates set wrong — feed not split across units.
Basket / deck angle too flat to move the pool.
Total flow exceeds combined deck capacity (high circulating rate).
Screens too fine for the rate across all decks.
A unit down for screen change while flow continues to the rest.
High viscosity / gel reducing throughput on every deck.
Surge of solids (connection, sweep) momentarily overloading the decks.
How to diagnose it
Check the distribution box / gates — is feed evenly split across units?
Compare total circulating rate against combined deck capacity.
Check screen API across all decks against the rate.
Confirm how many units are actually online.
Check rheology — thick mud lowers every deck's throughput.
The fix — step by step
Balance feed across all available decks via the distribution box.
Match screen API to the rate — coarser where decks are flooding.
Address rheology upstream if viscosity is throttling all decks.
Confirm it's fixed
✓ Verify: Feed split evenly across all decks with a beach re-established on each; no fluid over the back tank.
Field note. Before you blame the screens, look at the distribution box. The most common ‘overflowing shaker' is actually three decks doing the work of five because the feed never got split evenly — or a screen change left flow piling onto the units still running.