Module 2 · Inspection & Condition Monitoring
02
Lesson 2 of 5

Measuring Wear

Wear is not optional — every hydrocyclone erodes from the inside. The job isn't to prevent it, it's to measure it accurately enough to replace parts before they fail, and not a day sooner than necessary.

2.1 Why wear tracking matters

Slurry is abrasive by nature — it's a stream of hard mineral particles moving at high velocity against the vessel wall. Over time this erodes the liner. Left untracked, that erosion eventually breaks through, and a breakthrough failure is far more expensive than a planned liner change: it means an uncontrolled slurry leak, an emergency shutdown, and often damage to surrounding equipment.

Measuring wear regularly turns an unpredictable failure into a predictable, schedulable replacement. It also protects against the opposite mistake — replacing liners too early, which wastes budget and production time on parts that still had useful life left.

The goal: know how much liner thickness remains, know how fast it's disappearing, and use both numbers to schedule replacement before failure — not after it.

2.2 Where wear concentrates

Wear is never uniform across the vessel. Because velocity and particle impact angle change with geometry, some zones erode many times faster than others. Understanding this pattern tells you where to focus limited inspection time.

  • FEED INLET NOSEHighest-velocity impact zone; the incoming jet strikes here directly
  • LOWER CONE / APEXHighest wear zone overall — rotational velocity and particle concentration peak here
  • MID-CONEModerate, steady wear as the spiral tightens
  • CYLINDRICAL SECTIONLowest wear rate — flow is still developing and less concentrated against the wall

2.3 Measurement methods

Different methods trade off speed, accuracy, and whether the unit needs to be taken offline. Most inspection programs combine more than one.

MethodToolBest used for
Ultrasonic thickness gaugeUT gauge + couplant gelPrecise reading through the liner without cutting into it
Physical caliper checkVernier caliper / depth gaugeExposed liner edges during a shutdown
Visual baseline comparisonReference photos / wear templateFast go/no-go check between full measurements
Apex go/no-go gaugeSized plug gaugeConfirming apex bore hasn't enlarged past limit

Ultrasonic thickness gauging is the workhorse for most programs — it reads remaining liner thickness through the outer shell, so the unit doesn't need to be opened, and readings can be logged at the same points every time for a consistent trend.

2.4 Setting a replacement threshold

A liner should never be run to zero thickness. Most operations set a minimum safe thickness — often expressed as a percentage of the original — and schedule replacement once a unit crosses it, with margin built in for the time it takes to source and fit a new liner.

Remaining life (weeks) ≈ (Current thickness − Minimum safe thickness) ÷ Wear rate per week

This simple projection, taken from two or three consecutive monthly readings, is usually enough to schedule a replacement window weeks in advance — turning liner changes into planned work instead of emergency response.

Key Takeaways
  1. Wear concentrates in the lower cone, apex, and feed inlet nose — inspect these zones first and most often.
  2. Ultrasonic thickness gauging is the most practical routine method since it needs no shutdown and gives a repeatable number.
  3. A fixed minimum safe thickness, tracked against wear rate, turns liner replacement into planned work instead of a surprise failure.
  4. Consistent measurement points and consistent timing matter as much as the tool — a trend is only as good as its data.