This came up some while ago when I belive some Anshutz cyinders (aledgedly! I state for legal reasons although it is well documented) went pop. It is on every one of the target gun manufacturers sites FWB, Walther, etc, and Anschutz also have a picture of a blown cylinder if any one thinks its a joke.
The Anschutz cylinders were (aledgedly) defective ones and they will replace certain cylinders manufactured at certain dates free of charge, but this then set the beaurocratic Effing Safety machine going in Germany. These cylinders originally escaped legislation due to their size but with pressures of 4000 psi and being continualy pressured up and down, and with moisture also present the risk was recognised and the directive you have seen was the result. The single biggest action was the major manufacturers setting a 10 year life, this is almost certainly for their own legal protection, not our safety.
It came to a head last year when the ISSF started to enforce it at most big events, World Cup, Europeans, etc, the Germans in particular with great enthusiasm. It is unlikely to effect any one other than serious target shooters at the higher levels, I am not sure ( this is an opinion, not fact) but I do not believe it is enforcable in UK law, I think gun cylinders are too small under our law. It has effected the resale value of older PCP target guns as the cylinders have to be inside the 10 year rule, or replaced or serviced by the manufacturers.
BUT, in the event of an incident where no direct legislation applies, the HSE may apply the "best practice" rules and this could fall with in this area, I am a retired H&S manager for a major PLC and in the knowledge of the Anschutz incidents and the European action I would advise any manufacturer to give this some serious consideration. The European action is about ass covering and if I was a manufacturer I would do the same.
Best regards
Robin