Leak detection of equipment is a critical procedure in industrial production as well as the maintenance of pipelines and pressure vessels.
Below is a concise overview of 11 common leak testing methods, including their working principles,
features and applicable scenarios, for on-site technicians’ reference.
1.Soap Bubble Method
This is the most commonly adopted leak testing method in the industry.
The interior of the equipment is filled and pressurized with gas,
and soap solution is applied to the outer wall. Bubbles will form at leak points,
allowing rough estimation of the leakage rate.
Advantages: No production shutdown or equipment disassembly required;
the operation is not restricted by time. It is compatible with all types of gases within safe pressure limits.
2.Hydrostatic Pressure Test
It is specially designed for pressure vessels.
Fill the vessel with clean water completely and boost pressure with a hydrostatic pump.
Water has low compressibility and enables rapid pressure rise.
Even if the vessel cracks or fittings fall off, hazards are unlikely to occur,
so this method features excellent safety.
3.Sound Detection Method
This is a traditional and simple leak detection technique.
Escaping gas generates audible sounds,
and leak locations can be identified by the loudness and frequency of the noise.
Inspectors usually rely on bare ears or stethoscopes for testing.
Features: Low-cost and easy to operate. However,
the test is susceptible to ambient noise and fails to provide quantitative measurement of detection precision,
so it is only applicable for preliminary leak screening.
4.Ultrasonic Leak Detection Method
It is a mainstream high-precision leak testing solution.
It filters out ambient noise and amplifies ultrasonic waves generated by gas leakage for inspection,
with alarms triggered by instrument readings or audio alerts.
It boasts strong immunity to factory background noise and minimal human error.
Test results remain largely consistent when operated by different technicians,
enabling precise pinpointing of leak locations.
5.Rubber Membrane Method
This method is widely applied to gas pipelines in large industrial facilities.
Rubber sheets, funnels and thin films are pasted onto suspected leak areas.
Leaking gas will inflate the films, which can be directly observed by the naked eye.
It avoids errors from subjective human judgment and delivers intuitive, consistent test results.
6.Gas Tracer Detection Method
This method sees frequent application in industrial plants.
Inject special tracer gas into the vessel and place reactive media on its outer surface.
Leaks can be detected by gas detectors or test paper,
such as ammonia test paper for ammonia leakage inspection.
The operation is straightforward, but instruments need regular calibration to maintain testing accuracy.
7.Radioisotope Tracer Method
This method is dedicated to high-precision working conditions.
The equipment is pressurized with non-hazardous radioactive tracer gas,
and professional instruments are used to detect radioactive rays so as to locate leak points and estimate leakage rates.
Disadvantages: High cost and stringent professional competence requirements for operators.
8.Semiconductor Detection Method
This is an emerging leak detection technology.
It identifies leaks by detecting the change in conductivity of semiconductor materials when they come into contact with target gas.
It features accurate testing and high cost performance, yet the equipment suffers from average stability.
9.Halogen Pressure Detection Method
It is commonly used in power plants and large condensers.
Fill the equipment with halogen tracer gas.
The detector will give an immediate response once gas leakage happens.
This method boasts simple operation and great practicality.
10.Vacuum Bubble Test
This is a reverse leak detection technique.
Evacuate the vessel to create a vacuum, then coat suspected areas with liquids such as water or alcohol.
Leak points can be identified once liquid flow traces appear on the surface.
11.Thermal Conductivity Method
This method detects leaks by taking advantage of the differences in thermal conductivity among various gases.
The testing equipment delivers high precision, stable performance and great reliability, making it ideal for scenarios with stringent inspection standards.
Note: Reference for selection
Low-cost temporary inspection: Soap Bubble Method, Sound Detection Method
Pressure vessel hydrostatic test: Water Pressure Method
High-precision leak detection for complex working conditions: Ultrasonic Leak Detection Method, Halogen Pressure Method
Routine inspection of large pipelines: Rubber Membrane Method
High-precision special testing: Thermal Conductivity Detection Method, Radioisotope Tracer Method
Hidden leakage hazards cannot be overlooked.
Only by selecting the appropriate detection method based on equipment conditions and on-site working environments can production safety be guaranteed.
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