A tracer-gas leak testing method is a

nondestructive testing Nondestructive testing (NDT) is any of a wide group of analysis techniques used in science and technology industry to evaluate the properties of a material, component or system without causing damage. The terms nondestructive examination (NDE), n ...

method that detects

gas leaks Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or co ...

. A variety of methods with different sensitivities exist. Tracer-gas leak testing is used in the

petrochemical industry The petrochemical industry is concerned with the production and trade of petrochemicals. A major part is constituted by the plastics (polymer) industry. It directly interfaces with the petroleum industry, especially the downstream sector. Compa ...

, the

automotive industry The automotive industry comprises a wide range of companies and organizations involved in the design, development, manufacturing, marketing, and selling of motor vehicles. It is one of the world's largest industries by revenue (from 16 % such ...

, and in the manufacture of

semiconductors A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

, among other uses.

Types

Several tracer-gas leak testing methods exist, including: * Detection of leaks using

helium mass spectrometer A helium mass spectrometer is an instrument commonly used to detect and locate small leaks. It was initially developed in the Manhattan Project during World War II to find extremely small leaks in the gas diffusion process of uranium enrichment pl ...

, which provides high sensitivity *

Hydrogen leak testing Hydrogen leak testing is the normal way in which a hydrogen pressure vessel or installation is checked for leaks or flaws. This usually involves charging hydrogen as a tracer gas into the device undergoing testing, with any leaking gas detected by ...

, which provides the best mobility * Refrigerant gas leak detection, for refrigeration applications

Method selection

Typical leakage rates

The nature of the product or the process and the process gases will set the leak rate requirement:

Sensitivity of methods

Based on the target leak rate, the table below will help to choose the most suitable method.

Applications

Typical applications of tracer-gas leak testing include: * In petrochemical plants,

hydrocracking In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of ...

, vapocracking,

catalytic reforming Catalytic reforming is a chemical process used to convert petroleum refinery naphthas distilled from crude oil (typically having low octane ratings) into high-octane liquid products called reformates, which are premium blending stocks for high-oct ...

, and

steam reforming Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reaction of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen produc ...

are all

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxi ...

-based processes, in which were hydrogen leak testing is required. * When manufacturing

, all processes taking place in a process chamber at atmospheric pressure or under vacuum – diffusion, oxidation,

LPCVD Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (substra ...

PECVD Plasma-enhanced chemical vapor deposition (PECVD) is a chemical vapor deposition process used to deposit thin films from a gas state (vapor) to a solid state on a substrate. Chemical reactions are involved in the process, which occur after creat ...

, PVD and

ion implantation Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the physical, chemical, or electrical properties of the target. Ion implantation is used in semiconductor device fa ...

– require helium or hydrogen leak testing. * In vehicles,

airbags An airbag is a vehicle occupant-restraint system using a bag designed to inflate extremely quickly, then quickly deflate during a collision. It consists of the airbag cushion, a flexible fabric bag, an inflation module, and an impact sensor. Th ...

have to be tested for leaks so they remain functional for a long time. As well as airbags, the

air conditioning Air conditioning, often abbreviated as A/C or AC, is the process of removing heat from an enclosed space to achieve a more comfortable interior environment (sometimes referred to as 'comfort cooling') and in some cases also strictly controlling ...

system, fuel system, and exhaust system require testing for leaks. *

Pacemakers An artificial cardiac pacemaker (or artificial pacemaker, so as not to be confused with the natural cardiac pacemaker) or pacemaker is a medical device that generates electrical impulses delivered by electrodes to the chambers of the heart eit ...

and

catheters In medicine, a catheter (/ˈkæθətər/) is a thin tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. Cath ...

have to be tested for efficacy and longevity. * On planes, tracer-gas leak testing is used to quickly and safely locate fuel leaks, as well as to check oxygen distribution devices and

cabin pressurization Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft in order to create a safe and comfortable environment for passengers and crew flying at high altitudes. For aircraft, this air is ...

systems. * Refrigeration and air conditioning must have the lowest possible rate of loss of

refrigerant A refrigerant is a working fluid used in the refrigeration cycle of air conditioning systems and heat pumps where in most cases they undergo a repeated phase transition from a liquid to a gas and back again. Refrigerants are heavily regulated du ...

gases (contributing to

ozone depletion Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone la ...

). * Sewage and drinking water networks, to reduce loss of water and make sure drinking water is not contaminated by sewage.

Standards

Several standards apply to leak testing and more specifically to tracer-gas leak testing methods, for example: * BS EN 1779:1999; leak tightness by indication or measurement of gas leakage, * BS EN 13185:2001 Non-destructive testing. Leak testing. Tracer gas method, * BS EN 13192:2002 Non-destructive testing. Leak testing. Calibration of reference leaks for gases.

References

{{DEFAULTSORT:Tracer-Gas Leak Testing Method Tests Nondestructive testing Hydrogen technologies