Leak Testing Fundamentals That Should Know

Leak is a general term that you come across every now and then.

Generally, it is referred to the flow of gas or liquid through the wall

of a vessel through an imperfection such as hole or crack or a bad seal.

The flow of liquid or gas is generated due to the pressure

difference. Liquids or gases tend to flow from higher pressure to lower

pressure.

Leak Testing Massachusetts

• the units you can use

If you need to measure the leaks of gases into the atmosphere, then the

units are expressed as mm3 or cm3 (cc) per second or minute.

A standard unit of leakage for air pressure is mbarl/sec. (Millibar-litre

per second). A leak into atmosphere of 1 mbarl/sec equals a volume leak

of 1000 mm3/sec.

Leak detection

The methods used to detect leaks have common feature that is almost always

operator-dependent and require strict supervision. Also these processes

are very messy. There are many methods listed below that indicate a

leak, but these do not accurately quantify the degree of leakage.

Important observations

Components or samples are filled with pressurised gas and then immersed in a

liquid. They are filled with air or nitrogen under acetone. The

observation technique is to look for a bubble stream. The formation of

bubbles indicates the presence of leak.

Methods:

Chemical trace

Chemicals are added to the gas within the sample prior to some functional test.

If there is any leakage onto the surface of the component then it can be

readily seen using ultraviolet light.

Chemical penetration or dye penetration

Chemical is sprayed onto different sides of the component or sample. Then you

can see some actions happening on the sides of the sample’s surface due

to capillary action. This method is also called dye penetration method.

Gas sniffing

Sample components are filled with a gas that can be easily identifiable and

can create a pressure differential. Hydrogen, helium and sulphur

hexafluoride (SF6) gases are generally used as an operator to test

leaks. Helium is the most commonly used option, whereas SF6 is generally

avoided because it is highly toxic. Some electrical equipment are good

candidates of it because of its flame suppression properties.

There are many methods which work for leak testing. In fact visual inspection

can also work if the leaks are major. Material testing companies offer

these services by expert professionals with rich experience in the

industry. They also offer additional services like Digital imaging Massachusetts to ensure quality in various processes.

Abc Testing Incorporated is certified as Asnt Snt TC 1A, level Iii in Liquid Penetrant and visuals. We also offer Charpy Impact Testing new England, Bend Testing New England, Welding Inspection, Positive Material Identification.