Leak Detection
Content
Leak Detection with Penetrant Inspection Process
One of the many applications of liquid penetrant inspection is leak testing by enhancing visual detection of leaks. For leak testing, the liquid penetrant is applied on one side of the enclosing wall or surface of the test object and allowing time for the penetrant to seep through leaks and inspecting on the opposite side of the wall. The word “leak” refers to the physical hole. The word “leakage” refers to the flow of a fluid through a leak. Leak testing to detect and locate leaks is important to be able to repair unacceptable leaks in vessels or systems such as holding or process tanks, radiators, pipe systems, hydraulic systems, etc. Penetrant inspection of leaks is generally subjective as compared to the quantitative leak inspection using tracer gas and pressure change techniques. Both visible and fluorescent penetrants may be used as liquid dye tracers. Likewise, dye additives (ZL-5 and ZL-7) may be added to water or oil systems to enhance location of leaks. Leak Testing Techniques Using Penetrant Materials Inspection of empty vessels, tanks, or other liquid containment systems: Observe all safety precautions when inspecting enclosed areas. Make sure there is enough ventilation when using chemicals. If not, use self-contained breathing apparatus for oxygen source. Apply penetrant on the inside wall of the tank or area being inspected. Depending on the thickness of the wall, let penetrant dwell on the surface between 10-30 minutes. Allow a dwell time of at least one hour if the wall thickness is greater than ¼ inch. Apply developer on the other side of the wall. Observe indications where the developer was applied. When using SKL-4C or SKL-SP1 Spotcheck penetrant, use SKD-S2 nonaqueous developer and observe for red indications against the white developer background. For Zyglo fluorescent penetrant inspection (ZL-4C, ZL-19, ZL-60D), apply ZP-4B dry powder developer and observe fluorescent green indications using a blacklight in a darkened area. Inspection of closed systems such as radiators and engines: ZL-5 water soluble fluorescent additive may be added to water based systems (such as a large tank or pipe system containing water). ZL-7 oil soluble fluorescent additive (special order item) may be added to oil based systems (such as certain engines containing oil). The inspection
procedure is the same as for water based systems. The fluorescent additive is added to the system, the system is circulated, and the exterior is checked with a blacklight. The amount of ZL-5 or ZL-7 added to the test system is dependent on the volume of water or oil in the test system. Also, the fluorescent water or oil in the test system may be subject to waste disposal regulations when the inspection is completed.
One of the many applications of liquid penetrant inspection is leak testing by enhancing visual detection of leaks. For leak testing, the liquid penetrant is applied on one side of the enclosing wall or surface of the test object and allowing time for the penetrant to seep through leaks and inspecting on the opposite side of the wall. The word “leak” refers to the physical hole. The word “leakage” refers to the flow of a fluid through a leak. Leak testing to detect and locate leaks is important to be able to repair unacceptable leaks in vessels or systems such as holding or process tanks, radiators, pipe systems, hydraulic systems, etc. Penetrant inspection of leaks is generally subjective as compared to the quantitative leak inspection using tracer gas and pressure change techniques. Both visible and fluorescent penetrants may be used as liquid dye tracers. Likewise, dye additives (ZL-5 and ZL-7) may be added to water or oil systems to enhance location of leaks. Leak Testing Techniques Using Penetrant Materials Inspection of empty vessels, tanks, or other liquid containment systems: Observe all safety precautions when inspecting enclosed areas. Make sure there is enough ventilation when using chemicals. If not, use self-contained breathing apparatus for oxygen source. Apply penetrant on the inside wall of the tank or area being inspected. Depending on the thickness of the wall, let penetrant dwell on the surface between 10-30 minutes. Allow a dwell time of at least one hour if the wall thickness is greater than ¼ inch. Apply developer on the other side of the wall. Observe indications where the developer was applied. When using SKL-4C or SKL-SP1 Spotcheck penetrant, use SKD-S2 nonaqueous developer and observe for red indications against the white developer background. For Zyglo fluorescent penetrant inspection (ZL-4C, ZL-19, ZL-60D), apply ZP-4B dry powder developer and observe fluorescent green indications using a blacklight in a darkened area. Inspection of closed systems such as radiators and engines: ZL-5 water soluble fluorescent additive may be added to water based systems (such as a large tank or pipe system containing water). ZL-7 oil soluble fluorescent additive (special order item) may be added to oil based systems (such as certain engines containing oil). The inspection
procedure is the same as for water based systems. The fluorescent additive is added to the system, the system is circulated, and the exterior is checked with a blacklight. The amount of ZL-5 or ZL-7 added to the test system is dependent on the volume of water or oil in the test system. Also, the fluorescent water or oil in the test system may be subject to waste disposal regulations when the inspection is completed.
