PED compliance (in EU) for interconnecting pipelines

[Michele AZ]

Hello everybody,

my name is Michele, from Italy. This is the first time I write on this forum, but the users helped me a lot in the previous years, so thank you

We are currently have a job in which we have build interconnecting pipelines (made out of stainless steel), as well as piping supports (poles and brackets etc.). We did not design the process (it's a CO2 recovery plant), we did not set the DNs and the thk of the pipelines as well as we did not set the materials for all the pipelines, also we did not design the P&IDs and the line list.

All we did is designing the pipelines' paths within a CAD environment (with flanges and some valves provided by the process engineering firm, which is also the manufacturer of the machines which we are going to interconnect with out pipelines), the brackets and the poles. Eventually, we are manufacturing all of them.

The client hired a firm of professionals in order to get the plant certified, so they are evaluating the conformity of the overall plant. They reported to us that we (manufacturers of the interconnecting pipelines) shall provide pipe supports which are compliant with the PED, for the cat.II and III pipelines.

We are already providing all the sketches filled with 3.1 materials certificates, welding maps etc. but they insist on the supports matter, saying that we should use PED compliant supports (so with all the docs attached, 3.1 certificates, certificates of PED compliance of the manufacturers etc.). We are going to use (as we did many times in the past) just plain u-bolts, and maybe some raised clamp in order to support insulated pipes. The manufacturer of the u-bolts gave us a 2.1 certificate, stating that the u-bolts do not need any CE mark.

The pipelines are pretty straight forward: from a flange of a machine to a flange of another machine nearby, the path is pretty much linear, sitting on brackets made out of square pipes. We are going to fix them with simple u-bolts. Max pressure 24 bar, sizes from DN50 to DN200, Sch.10s and Sch.40, no corrosion implied.

I feel like they are asking too much, what do you think?

Thank you in advance,

Michele

 

[LittleInch]

Well to be pedantic, you are actually referring to pipes, not pipelines.

Also you don't say which design code you're working to?

I struggle to understand what a PED compliant Support looks like or is any different to any other support.

U bolts with clamp forces though are generally a pretty bad support design IMHO. They are notoriously difficult to decide what they are - an anchor, a guide, a clamp?

Ditto how much force they insert on fairly thin pipe and potentially cause damage or buckling. They have a very small contact area on the pipe so it results in a high stress concentration factor and point loads. You might struggle to get sufficient information to show it is PED compliant.





Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mk3223]

It looks that this is a major process piping for a CO2 Recovery Plant. I wonder that, in your Engineering Contract, it should define the requirements of the design and Code compliance for the piping work. IMO, you may need to have a stress analysis to confirm the proper and adequate supports for the large pipe size and pressure as mentioned.

The U-bolt support may be okay for the small bore piping with low pressure and temperature, but not for the large piping as well as the insulated pipes.

 

[XL83NL]

Correct, pipelines don’t fall under the scope of the PED, but I assume you meant a piping system.

Ask who ever told you this, where in Annex I of the PED such specific requirements are laid down for supports. The Annex I only has some general requirements on supports, but not anything like this.

The only case I can imagine is that the design code is EN 13480. That code deals with specific requirements on pipe supports, when such support are attached to a piping system that falls in either of the categories. Then, depending on the categories, the requirements increase (cat. III obviously setting more requirements than cat. I).

Huub
- You never get what you expect, you only get what you inspect.

 

[DekDee]

Agree 100% with XL83NL with regards to politely requesting where it is actually nominated in the PED.
Many, many hours have been wasted on many, many projects trying to comply with something that is on someones " wish list" but is not actually addressed in the code, standard or specification.

 

[GD2]

Michelle AZ,
I am not familiar with PED, but whoever created the ISOs must be also responsible for creating stress ISOs that determines the location and type of supports.
You didn’t mention about this. Wasn’t a detailed stress analysis required for this piping? You have mentioned that the piping size goes upto DN200. Most likely, a stress analysis is required unless you are duplicating a similar piping system with similar process conditions.

GDD
Canada

 

[Michele AZ]

Thanks everybody for the responses.

First, yes, I meant piping system, not pipelines (sorry!).

Then, I feel like I have to give you more details: we shall have supports that fall under the EN13480-3 (so S2 and S3 supports) as XL83NL mentioned. We did run a stress analysis for these pipes, consiedering U-bolts as the main fixing system.

To be more specific, this is the first plant we build for this client (we did other stuff in the past), but it has other plants very similar to this (the one we are making is next to another one) and had never a problem with clamps, ubolts etc. so does the process engineering firm (which is also a manufacturer) which never bothered to use systems different from clamps or ubolts for this kind of jobs.

We have just one DN200 pipe (with 2 small DN150 branches) that is at 24 bars. The other pipes that fall under PED are maximum DN80 (max 24bar) and the temperature range for this job is not relevant.

Again, thank you.

 

[XL83NL]

Then the design code dictates the requirements. EN 13480 has gotten you.
Its a harmonised standard, meaning compliance with EN 13480 automatically means compliance with the PED. In that regard, one might think that the PED has a requirement on supports, which in fact, it doesn’t. It’s the other way around.

Huub
- You never get what you expect, you only get what you inspect.

 

[GD2]

Michele AZ,
You said you have run a stress analysis. and asking us whether the U-bolt supports are acceptable.
Did you the stress reports and verify whether it met code requirement and passed?
With a stress analysis, things are very straightforward. It will give you the details of type of support, and location. If you didn't put approved support type, you need to rerun the analysis with correct supports.

GDD
Canada

 

[LittleInch]

I know this isn't what you asked, but the more I look at U bolts the less I like them.

The issue in your stress analysis is if you have regarded U bolts as anchors in x,y and Z? If you have then the reality is that these are not good at doing that and it creates stress concentrations in the pipe and is too dependant on how well or not the fitter tightens them up.

A 1" or 2" air line? fair enough. A high pressure stainless CO2 line maybe not so good.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.