8.—(1) Every union and joint on a pipeline or gas container must be constructed and fitted so that it will—
(a)not be liable to work loose or leak when in use; and
(b)be readily accessible for inspection and maintenance.
(2) Every union on a medium or high pressure pipeline or on a gas container must be made of suitable metal; but such a union may contain non-metal washers and seals provided that such washers and seals are supported and constrained by metal components.