The shale shaker is the first and most important stage of solids removal — and the unit with the most failure modes. Here is the deep reference: design and sizing, screens and deck, mechanical and vibration, electrical and control, and the operational failures the night crew fights, each traced from mechanism to correction.
Where it sits: the shaker receives returns from the flowline via the possum belly and screens out the coarsest drilled solids first, protecting the mud pumps and every downstream unit. Everything it fails to remove becomes a more expensive problem at the hydrocyclones, centrifuge and in dilution.
A shaker is only as good as how it was specified and set up. These faults are decided at selection and installation — and they cap removal efficiency no matter how the deck is run.
Too few shakers / undersized capacity for the flow
Mechanism
Total screening area is sized for a maximum return rate. When the rig drills bigger hole or higher rate than the shakers were specified for, the decks run flooded.
Shows as
Mud pools and runs off the end of the screens; fine screens cannot be used; solids bypass into the active.
Detect / inspect
Compare installed screen area and rated capacity against the maximum return rate for the largest hole section; watch for end-of-deck pooling at full rate.
Consequence downstream
Coarse screens forced in to keep up; LGS climbs; hydrocyclones and centrifuge overloaded; dilution rises.
Correction
Add shaker capacity or split flow; size the shaker package for the largest section's rate; don't compensate with coarse screens.
Wrong motion type for the duty
Mechanism
Linear, balanced-elliptical and circular motion convey and dry differently. The wrong motion for the fluid/solids gives poor conveyance or poor fluid handling.
Shows as
Poor conveyance uphill or wet, sloppy discharge; cuttings not drying; capacity lower than expected.
Detect / inspect
Identify the motion type and compare to the application (high-volume linear vs gentler circular for sticky solids); observe conveyance and discharge dryness.
Consequence downstream
Either solids carry-over (under-removal) or excess whole-mud loss to the cuttings (over-removal).
Correction
Match motion to duty; where fixed, tune G-force, deck angle and screen choice to get the best of the installed motion.
Incorrect installed deck angle / no adjustability
Mechanism
Deck (basket) angle sets the balance between fluid pool depth and conveyance. A wrong or non-adjustable angle floods the deck or dries it out.
Shows as
Pool too deep (flooding, fluid off the end) or pool gone (dry screening, poor capacity).
Detect / inspect
Check installed angle and whether it can be adjusted under load; observe pool position (should sit roughly two-thirds up the deck).
Consequence downstream
Lost capacity or solids bypass; screens worked outside their best window.
Correction
Set and maintain correct deck angle; ensure the adjustment mechanism works; re-trim as rate and fluid change.
Feed distribution / weir built for uneven loading
Mechanism
The possum belly weir must spread flow full-width. A bad weir or feed geometry loads one side or hits the screen as a jet.
Shows as
Streaked screen wear, one side flooded, screens cut by a concentrated stream.
Detect / inspect
Watch the overflow across the weir at full rate; map screen wear; check feed geometry.
Consequence downstream
Premature screen failure and local bypass; wasted screening area.
Correction
Restore a clean, level, full-width weir; fix the header box (see the flowline & header box page).
Poorly located / non-existent bypass and dump arrangement
Mechanism
Without a proper, controlled bypass for surges or screen changes, crews improvise — often sending unscreened mud to the tanks.
Shows as
Ad-hoc bypassing; unscreened returns reaching the active during surges or screen changes.
Detect / inspect
Check for a designed, lockable bypass; observe crew practice during connections and screen changes.
Consequence downstream
LGS spikes every time the bypass is used; the whole train pays.
Correction
Provide a controlled, flagged bypass; design screen-change practice so removal isn't lost; never leave bypass open as routine.
Screen & deck failures
The screen is the working surface and the most frequent failure point. Screen problems are part selection, part tensioning, part the deck and motion feeding them.
Screen blinding (plugging) by near-size particles
Mechanism
Particles close to the mesh opening lodge in and progressively block the openings, especially with sticky or barite-laden fluids.
Shows as
Fluid pooling and running off the end as open area drops; capacity collapses though the screen looks intact.
Detect / inspect
Look for fluid backing up over a clean-looking screen; check particle size vs mesh; note barite/sticky solids.
Consequence downstream
Capacity loss forces coarser screens or bypass; solids bypass downstream.
Correction
Select layered/3-panel screens with anti-blinding behaviour; adjust G-force and spray (where allowed); match mesh to the cut, not finer than the duty allows.
Screen blanking / mud or polymer coating
Mechanism
A film of polymer, lost-circulation material or coating mud seals the screen surface (distinct from particle blinding).
Shows as
Sheeting fluid over a coated surface; sudden capacity loss after a treatment or LCM pill.
Detect / inspect
Inspect for a continuous coating film; correlate with recent mud treatments/LCM.
Consequence downstream
Same as blinding — lost capacity and bypass; wasted screens.
Correction
Manage mud chemistry; control LCM at surface; clean or change coated screens; review treatment practice.
Premature screen wear / tearing
Mechanism
Abrasive solids, a concentrated feed jet, over-tensioning or worn deck rubbers tear screens early.
Shows as
Holes and tears; solids visibly passing through; very short screen life and high screen spend.
Detect / inspect
Map where tears occur (feed end = jet; edges = tension/rubber); check deck support rubbers and tension.
Consequence downstream
Solids bypass straight to the active; high recurring screen cost.
Correction
Fix feed distribution; correct tensioning; replace worn deck rubbers/supports; choose screen construction for the abrasion.
Improper tensioning (over/under)
Mechanism
Screens must be tensioned to spec. Over-tension splits the mesh; under-tension lets it flutter and fatigue.
Shows as
Edge tears (over) or fluttering and rapid fatigue (under); inconsistent life.
Detect / inspect
Check tension against OEM spec; listen/observe for screen flutter under vibration.
Consequence downstream
Short life and bypass; wasted screens.
Correction
Tension to OEM spec every change; inspect tensioning rails/wedges; train crews on correct procedure.
Worn deck rubbers / support cords and crown
Mechanism
The rubber supports and crowned deck hold and seal the screen. When they wear, the screen flexes wrongly and fluid sneaks past the edges.
Shows as
Edge bypass (fluid past the screen frame), screen fatigue, poor seating.
Detect / inspect
Inspect deck rubbers, support cords and the crown profile; look for fluid tracking around screen edges.
Consequence downstream
Bypass of unscreened fluid; premature screen failure.
Correction
Replace worn rubbers/cords; maintain the deck crown; reseat screens correctly.
Wrong API screen designation for the target cut
Mechanism
Screen mesh chosen too coarse passes solids; too fine blinds and loses capacity or removes barite.
Shows as
Coarse: solids bypass; too fine: flooding and barite loss.
Detect / inspect
Compare API designation to the target cut and the downstream split; see the screen cut-point calculator.
Consequence downstream
Either under-removal (LGS up) or over-removal (barite/whole-mud loss).
Correction
Select the finest screen the deck can carry without flooding; balance with hydrocyclones/centrifuge; recheck as the section changes.
Mechanical & vibration failures
The shaker is a vibrating machine under constant abrasive load. Its mechanical failures are about the basket, the springs, the bearings and the structure that make the motion.
Vibrator motor bearing failure
Mechanism
Vibrator-motor bearings carry high cyclic loads from the eccentric weights and eventually fail, especially with poor lubrication or ingress.
Shows as
Rising noise, heat and current; changed/asymmetric motion; eventual motor trip or seizure.
Detect / inspect
Vibration analysis, bearing temperature and motor current trend; listen for bearing noise; check lubrication schedule.
Consequence downstream
Loss of G-force/motion, screen blinding, and an unplanned shaker outage.
Correction
Condition-monitor bearings; lubricate to schedule; replace in matched pairs; keep spares; protect from washdown ingress.
Loss of G-force / wrong eccentric setting
Mechanism
G-force comes from speed and stroke (eccentric weight). Mis-set weights, wrong speed or a failing drive drop the G-force below what the screens need.
Measure G-force from stroke and rpm (see the G-force calculator); compare to the 4–8 G band and OEM rating.
Consequence downstream
Under-removal and blinding cascade into the whole train.
Correction
Set eccentric weights and speed for the target G-force; fix drive issues; verify with a measured check, not by feel.
Cracked basket / structural fatigue
Mechanism
Continuous cyclic stress cracks the basket, cross-members and welds, changing the motion and risking catastrophic failure.
Shows as
Cracks at welds/corners, changed or rattling motion, abnormal noise.
Detect / inspect
Periodic structural/weld inspection (dye-penetrant where needed); watch for motion changes and new noises.
Consequence downstream
Distorted motion ruins screening; a failed basket is a major outage and a safety risk.
Correction
Inspect and repair/replace per OEM; never run a cracked basket; address the root cause (resonance, overload).
Vibration isolators (springs/mounts) worn or broken
Mechanism
Helical springs, rubber mounts or air springs isolate the basket from the skid. Worn or broken isolators transmit vibration to the structure and distort motion.
Shows as
Skid shaking, uneven or rocking basket motion, accelerated structural fatigue.
Detect / inspect
Inspect springs/mounts for cracks, sag, or breakage; check basket sits level and moves true.
Consequence downstream
Poor screening from distorted motion; structural damage spreads.
Correction
Replace isolators as a set; level the basket; fix any resonance driving the wear.
Drive belt / coupling wear (belt-driven units)
Mechanism
On belt-driven shakers, worn belts and couplings slip and change the stroke/speed.
Shows as
Slipping, squeal, lost speed and G-force; inconsistent motion.
Detect / inspect
Inspect belts/couplings; check speed against rating; listen for slip.
Consequence downstream
Lower G-force, blinding, carry-over.
Correction
Tension/replace belts and couplings; align drive; keep them on a PM schedule.
Air-spring / pneumatic system faults (air-mounted decks)
Mechanism
Air-mounted shakers rely on regulated air for the springs/angle. Leaks or regulator faults change the level and motion.
Check air supply, regulators and for leaks; confirm level and angle.
Consequence downstream
Distorted motion and wrong pool depth → poor screening.
Correction
Repair leaks/regulators; maintain air supply; re-level and re-trim.
Electrical, motor & control failures
Shakers are electrically driven in a wet, classified area. Their electrical failures are about the motors, the starters/VFDs and the protection that keeps crews and kit safe.
Vibrator motor electrical failure / winding burnout
Mechanism
Moisture ingress, overload, single-phasing or bearing drag burns out vibrator-motor windings.
Shows as
Motor trips, won't start, runs hot, or one motor down (asymmetric motion).
Detect / inspect
Insulation resistance (megger), current balance, temperature; check seals and area rating.
Consequence downstream
Lost or distorted motion; deck down; screening compromised.
Correction
Replace/rewind to rating; fix ingress; ensure correct overload protection and area-rated motors.
Starter / VFD / overload mis-set or failing
Mechanism
Incorrect overload settings or a failing starter/VFD either nuisance-trips or fails to protect the motor.
Shows as
Nuisance trips or, worse, no trip on overload (motor cooks).
Detect / inspect
Verify overload settings vs motor FLA; check starter/VFD health and fault logs.
Consequence downstream
Unplanned outages or burnt motors.
Correction
Set overloads correctly; maintain starters/VFDs; keep settings documented.
Hazardous-area / Ex rating and bonding failures
Mechanism
Shakers sit where gas can be present. Non-rated equipment, damaged glands or poor bonding create ignition and shock risk.
Shows as
Non-Ex devices, damaged cabling/glands, missing bonding near the deck.
Detect / inspect
Verify area classification and Ex ratings; inspect glands, cabling and bonding/grounding.
Consequence downstream
Ignition/shock safety risk; potential incident in gas-cut returns.
Correction
Use correctly rated equipment; maintain glands/bonding; inspect cabling for abrasion.
Wash-down water ingress into electrics
Mechanism
Routine wash-down drives water into junction boxes, motors and connectors not sealed for it.
Shows as
Earth faults, trips, corrosion of terminals and connectors.
Detect / inspect
Inspect seals/IP integrity of boxes and motors; look for water and corrosion inside enclosures.
Consequence downstream
Electrical faults and outages; safety risk.
Correction
Maintain IP-rated enclosures and seals; train crews on wash-down practice; dry and treat affected gear.
Operational & process failures
The failures the crew fights every tour — driven by how the shaker is fed, set and managed against the fluid and the formation.
Flooding (fluid running off the screen)
Mechanism
Capacity exceeded — by rate, blinded screens, too-fine mesh, wrong angle or low G-force — so the pool runs off the end.
Shows as
Whole mud over the end of the deck; solids bypass; lost mud.
Detect / inspect
Observe pool position and end-of-deck overflow; check rate, screen condition, angle and G-force.
Consequence downstream
Direct solids bypass to the active and mud loss; dilution spikes.
Correction
Address the actual limiter (coarser only if needed, more capacity, correct angle/G-force, clean/replace blinded screens).
Dry screening / whole-mud loss to cuttings
Mechanism
Over-drying — too-coarse screens, too high G-force/angle for the fluid — throws usable mud over with the cuttings.
Shows as
Wet, mud-rich cuttings discharge; high mud-on-cuttings; rising mud cost.
Detect / inspect
Inspect discharge dryness and mud-on-cuttings; check G-force/angle vs fluid.
Consequence downstream
Expensive whole-mud loss and higher waste volume/OOC.
Correction
Trim G-force/angle and screen choice to keep solids moving without throwing mud; balance with downstream drying.
Solids bypass through damaged or bypassed screens
Mechanism
Torn screens, edge bypass or an open bypass send unscreened solids to the active.
Shows as
Rising LGS and sand in the active despite 'running shakers'.
Detect / inspect
Inspect screens and edges for holes/bypass; check bypass position; trend LGS/sand.
Consequence downstream
Loads hydrocyclones/centrifuge and forces dilution.
Correction
Repair/replace screens; seal edges; close improper bypass; screen don't bypass.
Wet cuttings / poor conveyance
Mechanism
Low G-force, wrong motion/angle, blinded screens or sticky solids stop cuttings conveying and drying.
Shows as
Cuttings not moving off the deck, wet sloppy discharge, bed building.
Detect / inspect
Observe conveyance and bed; measure G-force; check motion/angle and screen state.
This reference describes failure modes and engineering principles in general terms. Corrective actions must be matched to your actual equipment, fluid, formation and procedures, and carried out under the relevant rig and safety standards.
Grounded in standard solids-control practice and field references (drilling-fluid solids-control handbooks; API RP 13C screen practice; OEM guidance). SC DrillTech is independent and vendor-neutral.
Take it further
Tools and references built from the same field experience as this page — independent and vendor-neutral.
Are your shakers the limiter — or just where you see the symptom?
Flooding, blinding and bypass usually trace to feed, G-force, screen choice or upstream flowline issues. An independent evaluation measures the deck and follows the solids through the whole train, instead of just changing screens.
