PED Classification for Jacketed Pipe

[ENG2194]

Can someone comment on their experience classifying Jacketed Pipe (JP) for PED

From Guideline B-04 it sounds like JP would be classified as a vessel if the fluid designed to flow through the core pipe (secondary fluid) was anything but air. If that is the case, Guideline B-19 would seem to classify the JP as a chambered vessel in which case one would use the pressure volume and fluid of each the jacket and core to determine the PED category of each. The highest PED category would then be used.

If this is the right approach, would one consider the volume of the core chamber of "the vessel" (i.e. JP spool) up to the flanges?

 

[XL83NL]

This topic would better fit in the Pipelines, Piping and Fluid Mechanics engineering or CEN / ECN (eu standards) Code Issues forum, but Ill try to address your issue.

First, let me start by saying I think youve done some remarkable research into this issue. Most questions addressed on the PED are usually not that well thought out.

The jacket should be considered a second chamber, or containment, but not treated as a vessel, to my understanding. We have done 1 jacketed piping project in the past, and this was SEP, so that didnt gave me a decent trace.

Both the inner pipe and jacket are considered piping to my interpretation, so table 6 ÷ 9 apply. Therefore guideline B-04 does not apply. I would approach the jacket just like a pipe, and use guideline B-02 to determine it's category. Then, determine the category of the jacket again, using it's volume this time, and thus applying tables 1 ÷ 4. This way, you have fulfilled Annex II, article 3. Provide this approach to your NoBO, unless either case results in a module not higher than A (meaning 'self-certification').

 

[XL83NL]

Just to add, for guideline B-02, I would calculate the hydraulic diameter of the jacket and use that for the classification of the jacket to tables 6÷9.

 

[ENG2194]

The reason i assumed the JP would be considered a chambered vessel was article 2(3) where the last line reads:

"heat exchangers consisting of pipes for the purpose of cooling or heating air shall be considered as piping;"

if fluid flowing through the core of the JP is not air, would you still consider it as piping?

 

[ENG2194]

The reason i assumed the JP would be considered a chambered vessel was article 2(3) where the last line reads:

"heat exchangers consisting of pipes for the purpose of cooling or heating air shall be considered as piping;"

if fluid flowing through the core of the JP is not air, would you still consider it as piping?

 

[XL83NL]

This is a tricky one, I have to say. Provide your approach to the NoBo, and then please post his feedback here.

 

[ENG2194]

Here is the response from our NOBO:

The pipe would be evaluated as pipe and as a vessel (Volume), whichever category is higher would prevail for classification.
The jacket would evaluated as a vessel based on volume, since its acting as heat exchanger.

the evaluation would be from flange to flange for each independent chamber. The higher category of the two sides would define the assessment module and category of the item. However, if different categories the rules for each category can apply. Except for any shared pressure bearing items the higher category would be required.

 

[XL83NL]

Clear. Thanks for the reply. I concur with him

 

[XL83NL]

I just found guideline B-35; which I think addresses jacketed piping. I was not aware of this guideline, but just stumbled upon it while looking for some other details. Does this shed a new light on the situation for you?

 

[ENG2194]

yes!! i believe this is exactly what i needed. No explanation on how to calculate though. (hydraulic diameter or actual diameter??)

 

[XL83NL]

I’d use the hydraulic diameter with guideline B-02 as justification.

 

[ENG2194]

XL83NL you have been most helpful! thank you!

 

[XL83NL]

You’re welcome. Hope to see you around here more often.