# Leak testing (LT)

> Leak testing (LT) detects and locates leaks in pressure boundaries using methods that range from bubble solution and pressure-decay measurement to helium mass-spectrometer tracer-gas detection.

- Source: https://amps.global/glossary/leak-testing/
- Type: Glossary
- Published: 2026-09-05
- Tags: NDT, leak testing

## Key facts

- Methods in order of sensitivity: bubble test, pressure or vacuum decay, halogen or helium sniffing, helium mass spectrometry
- Vacuum box testing checks storage tank floor welds per API 653
- Codes: ASME BPVC Section V Article 10; pneumatic tests need strict safety controls
- Result is usually a leak rate compared with an acceptance value, not an image

Also known as: LT, leak detection, tightness testing.

## How it works

The component is pressurised, evacuated or filled with a tracer gas and the escape of fluid is detected directly (bubbles, sound, sniffer probe) or inferred (pressure change over time). Tracer-gas methods can find leaks far below what a hydrostatic test would reveal.

## Where it is used

Storage tank floors and repairs, heat exchangers, vacuum systems, refrigeration and gas equipment, and post-repair verification during shutdowns.

## LT in AMPS

Test gauges and detector calibration certificates are tracked on the AMPS equipment page with expiry flags, and the test record is produced from your own Word template with job data filled in automatically.

## Related pages

- [API 653](https://amps.global/glossary/api-653/)
- [Calibration certificate](https://amps.global/glossary/calibration-certificate/)
- [How to manage a shutdown with AMPS](https://amps.global/case-studies/03-shutdown-management/)

## Sources

- [Leak detection on Wikipedia](https://en.wikipedia.org/wiki/Leak_detection)
- [ASME Boiler and Pressure Vessel Code](https://www.asme.org/codes-standards/bpvc-standards)
- [API - American Petroleum Institute standards](https://www.api.org/products-and-services/standards)