Process Piping CE certification detail etc. ??????

So I have been asked to help out the guy on site who is doing the CE self certification on the factory machines. He wants me to do the assessments on the interconnecting pipe systems.

Here is my problem. I haven't seen this done before and either has he so we aren't sure what format or detail I need to go in to.
The "Pressure Equipment Directive" isn't any help as it only really deals with the responsibility of the pipe/fitting vendors to certify their items and says a little on adequate support etc. It doesn't deal with the safety of an installation.

So do I need to check the process design is safe and correct? Do I only need to check the fittings have the pressure rating on them? Do I need to find the data sheets on PRV's, pressure switches, valves etc. to prove they are CE marked and correctly rated for the design?

Has anyone ever done this or have any experience at all with it.? We are looking at low pressure systems here (transport of liquid chocolate at either 30 deg C or 42 deg C)

Food service ...alittle out of my line, but I have alittle pharmaceutical experience ...semi close. So I'm guessing this piping is stainless steel, so the first thing I'd check and get record of is if they did a "pickling" of the pipe to eliminate any carbon steel tool contamination. Next I'd look at how/when any leak tests were done on this piping plus record of it. I'd get the Process Flow Diagram and look at operating pressures/temp.s and verify that all in-line valving, Instrumentation, & etc. can operate inside the parameters set in the PDF. And lastly see if the piping construction followed any piping spec.s that were apart of the design. ...Good Luck!

Thanks for that but unfortunately nearly all that information is missing or hugely out of date. That's the main reason they need to go though this CE process. Newer installs would have all the information and be most likely CE compliant from design stage.