Are gas tanks pressurized

Liquid gas tank inspection: obligations, costs and more

How often does a gas tank have to be checked?

A liquid gas tank must undergo an external test before it is used for the first time, then every two years and usually an internal test every ten years. In these legally prescribed container tests, it is checked whether the requirements for the installation of the container and the material requirements are still met. In addition - depending on the liquefied gas supplier - more
Exams are added. Here is an example:


  • External inspection every 2 years
  • Internal inspection every 10 years
  • Calibration and replacement of the gas meter every 8 years or, if the sample test is passed, extension by 4 years and no replacement
  • Inspection of the pipelines every 10 years
  • In the case of commercial use, the tests of the consumption systems can also include shorter test periods
    (e.g. 1-4 years).


The tests are regulated by several directives and laws, including:


  • Technical rules for liquid gas (TRF)
  • Technical rules for the Industrial Safety Ordinance (TRBS)


What does the LPG system test include?

LPG system check before commissioning

Before the container is filled for the first time and goes into operation (i.e. the consumable device operated with it is switched on), both the tank and the consumable devices and lines connected to it must be checked. Specifically, these are the pipeline (supply line to the main shut-off device and the consumption line from the main shut-off valve to the consumer device) and the consumer device with the exhaust system (if present). All steps of the LPG system test are documented. In addition, the customer receives instruction in the use of his liquid gas system.


Recurring external inspection for liquid gas tanks

The external test is a visual and leak test. For example, the fittings, the area around the tank are checked for vegetation and compliance with safety distances to fire loads and the condition of the tank as a whole. It is also checked whether the technical data of the container match the information in the relevant documents.


Recurring internal inspection for liquid gas tanks

The internal liquid gas tank test determines, among other things, whether

  • the overfill protection is functional,
  • the safety valve works and all other tank fittings are in proper condition,
  • the tank's corrosion protection is still in order and no rust or deposits have formed on the tank and
  • the installation conditions are still met.

In the meantime, there are new test methods that no longer make it necessary to open underground and above-ground containers. The feed-in test and the noise emission test should be mentioned here.


Feed-in test

The aim of this test procedure is to assess the effectiveness of the container insulation. The prerequisite is that the liquid gas tank is coated with epoxy resin and that there are no fixtures or anti-buoyancy devices.


Acoustic emission test

During the acoustic emission test, the internal pressure of the container must be increased by heating the gas (approx. 10–11 bar). In addition, depending on the size of the container, one or more pressure sensors are installed at defined locations on the container. The evaluations of the pressure transducers are measured continuously and if no major fluctuations occur, the container can be operated for another 10 years. This test is intended to provide information about the material properties of the container.


Recurring pipeline test or leak test

In the case of privately used liquid gas systems, the pipes must also be checked every 10 years. This affects the supply and consumption lines. To do this, the pipelines are pressurized with a test medium (nitrogen or air). Thereafter, a waiting time of 10 minutes for above-ground pipes and 30 minutes for underground pipes must be observed for temperature equalization. The 10-minute leak test can then be carried out. Further specifications can be found in the technical rules for liquid gas (8.4.3.).


Who is allowed to test liquefied gas systems?

  • The external inspection of gas tanks after 2 years must be carried out by a qualified person.
  • The internal inspection after 10 years, on the other hand, can only be carried out by an approved monitoring body (ZÜS; in Germany TÜV NORD, MOT South, TÜV Rheinland, TÜV Thuringia, TÜV Saarland, TÜV Hessen and DEKRA) respectively.
  • The recurring pipeline tests can be certified by the specialist company (heating engineer) at a pressure of less than or equal to 0.5 bar and by a person qualified to perform the test at a pressure greater than 0.5 bar.