Thickness Gauge Calibration Check
This procedure ensures handheld ultrasonic and dial thickness gauges deliver accurate readings by performing zero verification and multi-point checks against certified standards. Regular calibration checks prevent material waste, non‑conforming product, and safety risks from undetected corrosion or wear.
The purpose of this calibration check is to verify that all thickness gauges in service produce measurements that are traceable to national standards and within the required tolerance (typically ±0.001″ or ±0.025 mm). Accurate thickness measurements are critical for maintaining wall thickness in pressure vessels, pipelines, and structural components, as well as for ensuring dimensional compliance of manufactured parts.
This procedure applies to all handheld ultrasonic thickness gauges and dial thickness gauges (e.g., magnetic, mechanical) used in the facility for in-process inspection, incoming quality, and maintenance thickness surveys. It covers calibration verification only — full calibration adjustment must follow the manufacturer’s formal procedure if verification fails. All technicians performing this check must be trained on gauge operation and the contents of this SOP.
- Wear clean safety glasses to prevent accidental contact with couplant or debris. Handle all calibration standards with care to avoid cuts from sharp edges.
- Couplant fluids are generally non‑hazardous, but avoid skin contact if allergic. Wash hands after handling. Store couplant in sealed container.
- Certified calibration thickness standards (step wedges or shims covering gauge range)
- Clean lint-free cloth (microfiber recommended)
- Couplant (ultrasonic gel) – for ultrasonic gauges only
- Thickness gauge under test (fully charged or with fresh batteries)
- Ambient temperature thermometer (optional, required if gauge has temperature compensation)