To ensure cylinders continue their safe use, there are a number of regulations which demand that a periodic examination or test has to be performed, with a satisfactory outcome, by the cylinder’s owner.
The frequency of the test is a variable from one set of regulations to another and even varies within a particular regulation. The test interval depends primarily on the gas contained and the cylinder material (or materials in the case of composites – see Part 4), though a number of other risk factors, often covered by the owner’s quality system, are also relevant (see Test Intervals below). To support the regulations there are both national and international standards which give details of the work which has to be undertaken. The most widely used of the International Standards is probably ISO 6406 revised in 2006, while EN 1968 is also in common use.
It will be very difficult to cover all the various combinations of tests that are required for a successful retest programme. The much specialised area of acetylene cylinders is not covered here and will be the subject of a separate article. What follows is a useful summary of some key aspects and the way events are likely to progress in future. I will be pleased to expand any points in this complex field, which the readers may have.
The traditional test
The periodic inspection, often referred to as a retest, or a requalification, has been performed for over a century. It has key components which all need to be performed and passed. The work relies heavily on the competence of the inspector since some aspects can be subjective. The subjectivity is reduced and a more objective outcome can result with increasing experience on the part of the inspector. The key components which need to be covered for seamless and composite
cylinders are:
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