4.1 Why documentation matters
A single inspection tells you the condition of a unit on one day. A logged history of inspections tells you how that condition is changing — and change over time is what actually predicts failure. Without records, every inspection starts from zero: no baseline to compare against, no wear rate to project forward, no way to know if today's reading is normal or a warning sign.
Documentation also does work beyond prediction. It creates an audit trail for warranty claims, gives the next shift or the next technician full context instead of a verbal handover, and gives reliability teams the data they need to make plant-wide decisions about spares, budgets, and replacement scheduling.
4.2 What every record needs
Date, time, and inspector
Who checked the unit and when — the minimum needed to trust and trace any record.
Unit identification
A clear tag number or location ID — critical in a cluster where dozens of nearly identical units run side by side.
Measurements against baseline
Liner thickness, apex diameter, or any other measured value, recorded next to the original baseline for instant comparison.
Photos of findings
A photo settles disputes and disagreements about severity that a written description alone often can't.
Corrective action and next due date
What was done (or needs to be done) and when the unit is due for its next check — closing the loop.
4.3 Paper vs. digital logs
| System | Strength | Weakness |
|---|---|---|
| Paper checklist | Fast, no training needed, always available | Hard to trend, easy to lose, no automatic alerts |
| CMMS / digital log | Searchable history, automatic trend charts, scheduling alerts | Needs consistent data entry discipline to stay useful |
Most plants use both in practice — a paper or tablet checklist on the floor that feeds into a digital system afterward, giving the speed of paper with the long-term value of a searchable record.
4.4 Turning records into trends
The real value of documentation shows up once you have three or more data points for the same unit. Plotting liner thickness against date turns a stack of individual readings into a wear-rate line — the same projection introduced in Lesson 2 — and that line is what lets a reliability team schedule a replacement weeks ahead instead of reacting to a low reading in the moment.
- An inspection without a record only tells you about today — a logged history is what lets you predict tomorrow.
- Every record needs, at minimum, who, when, which unit, measurements against baseline, and next steps.
- Photos resolve disputes about severity that written notes alone often can't.
- Trends only emerge after three or more consistent readings — consistency in what and how you record matters as much as recording at all.