PED 2014/68/EU - Assemblies 1

[IdanPV]

Hello all,

I would like to consult regarding the definition of an "assembly" as per PED 2014/68/EU.
The system I have contains the following pressure equipment:
* Steam Generator (MAWP=5 Barg) - Category III
* Pressure Vessel (MAWP=3 Barg) - Category III
* Piping System with DN<32, piping is classified as SEP.
* Pressure Relief Valves which manufactured by PRVs manufacturer.
See illustration below

All the items are CE marked and supply to the user with Declration of Conformity.

According to Artice 2:
assemblies means several pieces of pressure equipment assembled by a manufacturer to constitute an integrated and functional whole.
That's my case I think.

According to Article 4(2):
The following assemblies which include at least one item of pressure equipment covered by paragraph 1 shall satisfy the essential safety requirements set out in Annex I:
(a) assemblies intended for generating steam or superheated water at a temperature higher than 110 °C comprising at least one item of fired or otherwise heated pressure equipment presenting a risk of overheating;
(b) assemblies other than those referred to in point (a), if the manufacturer intends them to be made available on the market and put into service as assemblies.
My questions are:
1. It seems that the steam generator is meet the definition of Article 4(2)(a), but what about the assembly which contain the piping and the vessel?
2. Does the complete assembly which contains all the item described above shall meet the ESR set out in Annex I?
3. Does the complete assembly which contains all the item described above shall be marked with CE and supply with Declration of Conformity?
4. Article 4(2)(b) allows the manufacturer to decide whether to classify the equipment as an assembly. What could be the consequences if the system described above is not classified as an assembly?

Thanks,

 

[AKuep]

1. It seems that the steam generator is meet the definition of Article 4(2)(a), but what about the assembly which contain the piping and the vessel?
confirmed
2. Does the complete assembly which contains all the item described above shall meet the ESR set out in Annex I?
Yes. Assembly means all items incl. pipings and pressure accessories even if only SEP.
3. Does the complete assembly which contains all the item described above shall be marked with CE and supply with Declaration of Conformity?
Yes incl. conformity assessment procedure (risk analysis, operating instruction, Final Documentation), Name plate, CE marking, DoC
4. Article 4(2)(b) allows the manufacturer to decide whether to classify the equipment as an assembly. What could be the consequences if the system described above is not classified as an assembly?
Article means complete assemblies ready for use.
It is not prohibited to place the individual pressure devices separately on the market. Someone then has to carry out the assembly and perform the conformity assessment procedure. This can also be the end user.

 

[XL83NL]

I’ll try and provide a first short answer. More extensive reply with details - if required - later.

1. Individual items remain as they are. SEP piping stays SEP piping. Etc

2. Yes. However for assemblies it is different. I can provide you with a typical list of documents that we make for our assemblies.

3. Yes. On the assembly.

4. It will then not be CE-marked, and you may violate legislative requirements. It depends if the assembly constitutes a ‘functional’ whole.


Also, bear in mind you must perform a hazard and risk analysis. That may indicate you’re PID isn’t ‘safe’ and requires modification. I’m not a chemical or process engineer (but mechanical), but I know a thing or two about the PED. This PID doesn’t seem complete. Not u til its hazoped and safe, you can apply the CE mark. No nobo is likely to give a design appraisal for this if it hasn’t been properly hazoped or process safety verified.

 

[IdanPV]

@AKuep and @XL83NL, thank you very much for your detailed answers.

I do have some more questions,
1. Does a hydrostatic test per ANNEX I, 7.4 is required? in what pressure?
2. What does "functional whole" mean?

XL83NL,
The PID is for illustration purpose only, and it isn't the actual PID which in use.
The actual PID is much more detailed and complex.

Thanks,

 

[AKuep]

1. The pressure test must be carried out as part of the final inspection of the assembly.
If water pressure testing is not possible or impractical, a pneumatic pressure test can also be carried out.
If pressure tests have already been carried out for all individual pressure devices including connection piping, the test can be limited to a leak test of all assembly connections if necessary: Risk analysis, agreement with NB.
For test pressure: max. load factor against yield point: 1.05.

2. They form a whole (all the items which are necessary for the assembly to function and be safe are present). Safety and function are only guaranteed if a described assembly is complete.

 

[IdanPV]

Thank you.
Where is the value of 1.05 came from?
Annex I. 7.4 does not iclude this value, and the calculated value should be against the Ps value, not the yield point.

 

[XL83NL]

Thank you.
Where is the value of 1.05 came from?
Annex I. 7.4 does not iclude this value, and the calculated value should be against the Ps value, not the yield point.

1.05 just is 5% above a certain value (probably a safety margin to some extent), that was once chosen by CEN. If you take 1.5 (which is the factor to yield, i.e. 2/3) and divide it 1.05, you get the infamous 1.43.
See also https://www.eng-tips.com/threads/how-was-ped-97-23-ec-test-pressure-coefficient-1-43-derived.364778/

Not sure why AKuep referenced that value here, i don't see how it relates

1. The pressure test must be carried out as part of the final inspection of the assembly.
If water pressure testing is not possible or impractical, a pneumatic pressure test can also be carried out.
If pressure tests have already been carried out for all individual pressure devices including connection piping, the test can be limited to a leak test of all assembly connections if necessary: Risk analysis, agreement with NB.
For test pressure: max. load factor against yield point: 1.05.

2. They form a whole (all the items which are necessary for the assembly to function and be safe are present). Safety and function are only guaranteed if a described assembly is complete.

Correct; we have all our subassemblies and individual pressure equipment (piing and vessels) all hydrotest individually. If we combine them, we have to do a leak test at a certain pressure. Our Nobo will have to witness that leaktest for certain nodes, depending on the CAM (Conformity Assessment Module) that applies to the assembly.

As per 2; this has been a long-standing point of discussion for us. There's this (somewhat) older PED document by CEN on assemblies, which says a few things about functional whole; https://ec.europa.eu/docsroom/documents/24721. But its not that prescriptive. Also, there's a draft PED guideline on functional whole, but I recently checked with Brussel - they mentioned there's been debate about this guideline for years already, and they don't anticipate a resolution on short notice. to me this means Brussel (where the NoBo's) gather) cant find any consensus on this topic. So its even harder for us.

PS: there are also the PED CABF recommendations, that may help for certian topics (incl. assemblies). These documents are made by the Notified Bodies. Googling them doesnt lead to direct hits, given the ipression theyre kept somewhat secret. https://www.google.com/search?q=ped+cabf+recommendations. CABF-R-045 is specifically about leka testing assemblies; https://unm.fr/wp-content/uploads/2024/09/cabf_en.pdf

The issue we found is that some manufacturers or suppliers declare something to not be a functioning item (even though we think it is) and then not provide CE. They only tell you after buying their equipment and paying for the whole stuff; once the documents arrive at site, an EU DoC is missing. We then have to apply CE, taking over a whole lot of responsibilities and liabilities; this is a big issue for a lot of reasons. Make sure upfront, before paying, what youre gonna get.

XL83NL,
The PID is for illustration purpose only, and it isn't the actual PID which in use.
The actual PID is much more detailed and complex.

Thanks,

Understood. Good to hear. Just make sure youre system is haropped. Also, the EN 764-7 may help in some circumstances, as its the only harmonized standard for assemblies afaik.

 

[IdanPV]

@AKuep and @XL83NL , thanks again,

A pressure tests have already been carried out for all individual pressure items, does a leak test of all assembly connection is permissible?
Can you please point me to a paragraph in the Directive which allow this?
How exactly this test is preformed?

Thanks,

 

[AKuep]

The requirements for the final inspection in the PED are the same for assemblies as for individual pressure equipment.
A pressure test is primarily a strength test and an integrity test to verify the design, provide proof that the enclosed space is tight during the test load.
Of course, in most cases a hydro test can also be used to check for leaks. However, other leakage tests can also be useful.
As already mentioned, a pneumatic pressure test is permitted if a water pressure test is impractical or not possible.

As already mentioned, a risk analysis should include the manner of this test.