To exempt certain situations from the application of the first part of this Sentence [Sentence 4.6.6.5.(6)], which would otherwise require piping to conform to Section 4.5., and permit alternate means of transfer [flexible hose], if certain measures are taken [suitable lengths of flexible hose designed in conformance with good engineering practice].
These measures are to limit the probability of the escape of liquid [e.g. hose rupture], which could lead to harm to the public.