Hydrogen leak testing
Encyclopedia
Hydrogen leak testing is the normal way in which a hydrogen
pressure vessel or installation is checked for leaks or flaws. There are various tests.
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
pressure vessel or installation is checked for leaks or flaws. There are various tests.
- The Hydrostatic testHydrostatic testA hydrostatic test is a way in which leaks can be found in pressure vessels such as pipelines and plumbing. The test involves placing water, which is often dyed for visibility, in the pipe or vessel at the required pressure to ensure that it will not leak or be damaged. It is the most common method...
, The vessel is filled with a nearly incompressible liquid - usually waterWaterWater is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
or oilOilAn oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
- and examined for leaks or permanent changes in shape. The test pressure is always considerably more than the operating pressure to give a margin for safety, typically 150% of the operating pressure. - The Burst test, The vessel is filled with a gas and tested for leaks. The test pressure is always considerably more than the operating pressure to give a margin for safety, typically 200% or more of the operating pressure.
- The Helium leak testHelium mass spectrometerA 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 plants. It typically uses a vacuum chamber in which a...
, The leak detection method uses heliumHeliumHelium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
(the lightest inert gas) as a tracer gas and detects it in concentrations as small as one part in 10 million. The helium is selected primarily because it penetrates small leaks readily. - Usually a vacuum inside the object is created with an external pump connected to the instrument.
- Alternatively helium can be injected inside the product while the product itself is enclosed in a vacuum chamber connected to the instrument. In this case Burst and leakage tests can be combined in one operation.
- The Hydrogen sensor, The object is filled with a mixture of 5% hydrogenHydrogenHydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
/ 95% nitrogenNitrogenNitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
, (below 5.7% hydrogen is non-flammable (ISO-10156). This is called typically a sniffing test. The handprobe connected to the microelectronic hydrogen sensors is used to check the object. An audiosignal increases in proximity of a leak. Detection of leaks go down to 5x10-7 cubic centimeters per second http://www.reedlink.com/SingleArticle~ContentId~11957~pub~IA.html. Compared to the helium test: hydrogen is cheaper than helium, no need for a vacuum, the instrument could be cheaper.
See also
- Hydrogen analyzerHydrogen analyzerA Hydrogen Analyzer is a device used to measure the hydrogen concentration in steels and alloys. It also has industrial applications for Corrosion Monitoring.-See also:* Hydrogen embrittlement* Hydrogen sensor* Hydrogen leak testing...
- Hydrogen pipingHydrogen pipingHydrogen piping, in industrial settings, is a system of pipes used to move hydrogen. Due to issues with hydrogen embrittlement, and corrosion, materials for hydrogen pipes must be carefully selected...
- Hydrogen safetyHydrogen safetyHydrogen safety covers the safe use and handling of hydrogen. Hydrogen poses unique challenges due to its ease of leaking, low-energy ignition, wide range of combustible fuel-air mixtures, buoyancy, and its ability to embrittle metals that must be accounted for to ensure safe operation...
- Tubing (material)
- Hydrogen stationHydrogen stationA hydrogen station is a storage or filling station for hydrogen, usually located along a road or hydrogen highway, or at home as part of the distributed generation resources concept. The stations are usually intended to power vehicles, but can also be used to power small devices. Vehicles use...
- Tracer-gas leak testing methodTracer-gas leak testing methodTracer-gas leak testing method is a nondestructive testing method.-Types:Several tracer-gas leak testing methods exist among which the methods of choice are:* Helium mass spectrometer or helium leak detection, providing the highest sensitivity...