Sentence 4.5.2.1.(6)

Intent 1:

To exempt steel piping systems involving high service pressures from the application of Sentences 4.5.2.1.(3) and (5) if certain standards are met. This is to limit the probability that:

• internal stress or mechanical damage will lead to failure of the piping,
• piping and fittings will leak prematurely, or
• a chemical reaction with the liquid will lead to premature corrosion of the piping, which could lead to failure of the piping.

This is to limit the probability of the escape of liquid, which could lead to the ignition of vapour from a nearby ignition source, which could lead to harm to persons.