PD5500 Project Advise

[MattC-1]

Hi all,

I am looking for some advice on designing a pressure vessel to PD5500.

I have a masters degree in civil engineering so am theoretically qualified to do the design, but myself and my company has not designed any 'proper' pressure vessels before - although we've made plenty of components (mainly fuel injectors) that do see high pressure flows through them. We have purchased a copy of PD5500 from BSI and are looking forward to diving in with the design!

The vessel to be designed is a stainless 316L air receiver with an operating pressure of 25 Bar. It will only be used for internal use, we are not selling it to customers. We will be purchasing metric stainless tube and end caps from Aalco and then subcontracting certified welders to join the three components and install threaded ports top and bottom.

I am more than able to do the calculations and drawings for the vessel, but I understand that I need to involve a notified body to get approval of the design?

Does anyone have any recommended companies that are willing and able to be the notified body/inspecting authority in the UK?

We are hoping to use Cat 3 construction by derating the design stress of the stainless to 150MPa x 0.8 = 120 Mpa (the yield strength is below 230MPa) as per 3.4.2.2 as this simplifies inspection somewhat and improves safety factors. We already know that the vessel will be made out of 3mm stainless which even at this de-rated design strength of 120 MPa could support a design pressure of 35 Bar.

I was also wondering whether Section 1.1.3, attached, permits us to self certify the vessel without involving a third party as the tank is for internal use? We have other equally qualified engineering designers that could sign off on the drawing and verify the calcs. In this instance I assume we would just keep detailed design calcs, drawing and a completed form X on record and then install a name plate on the vessel with requisite information?

Many thanks for the help in advance.

 

[CuMo]

For 25 Bar G - most likely you would need the involvement of a NoBo.
Not sure what your vessel volume is but with such high pressure - it will most likely fall either in Risk CAT III or CAT IV.
(100 litres is somewhat the limit for CAT III). Both will require the involvement of a NoBo.
Also be aware that after Brexit - the rules of the PESR 2016 apply.

https://assets.publishing.service.g...to-pressure-equipment-regulations-2016-tp.pdf

I suggest go to either TUV UK or LLoyds Register UK.
Both can provide sufficient expertise.

Not sure whether you need to UKCA (This is the CE equivalent currently for the UK) certify the vessel if you're not placing it on the market
but I'm pretty sure it must be registered with a NoBo.

You can download this tool for free and see where your vessel falls under the PED/PESR.

https://www.lr.org/en-gb/pressure-equipment-directive/ped-software-tools/

Or you can save yourself a whole lot of hassle and let us do it for you quickly and efficiently. )

P.S. be aware that the lower temperature limit for CAT 3 is 0 deg C.
Air receivers tend to cool down during rapid discharge so that might be a show stopper.


Personally I would stay away from CAT 3.
I have never seen anyone use it so far.
I suggest use CAT 2 as a minimum. Spot X-RAY all butt-welds and Dye Pen all welds as a minimum.

 

I have a masters degree in civil engineering so am theoretically qualified to do the design

And I have a masters degree in mechanical engineering, but since electricity is like magic to me I don't try to design power grids, despite having a license to do so.

More to the point, buying a PV Code and some software is insufficient to prepare one for the task of PV design.


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[r6155]

@ MattC-1
I´m sure you can design a spaceship.
But now I suggest you contact a pressure vessel engineer.

If you insist that you can do everything, I suggest you install this pressure vessel near your desk.

Regards

 

[DriveMeNuts]

I don't think you have adequate qualifications or experience to undertake this project.
ASME VIII Div 2 specifies that to be a pressure vessel designer, the engineer shall have 4 years of experience under a mentor.

 

[KevinNZ]

Here in NZ we have regulated 3rd part design verification and sign off of the fabrication and installation by pressure equipment inspectors. This process would ensure the design is valid even if the designer does not have experience. Sounds much like the UK. Do the UK regulators have an approved list of design notified body/inspecting authorities?

I agree where there no required external oversite then pressure equipment should no be undertaken by inexperienced designers without review. We all have to start some where.

 

[DriveMeNuts]

The purpose of a 3rd party appraiser is to provide a layer of safety by checking and verifying that a competent vessels designer complies with code rules has not made any errors.

If the vessels designer has little experience and has therefore not achieved competence, then effectively the 3rd party appraiser becomes the sole designer and therefore there is no check and verify layer of safety. TO make it even worse, in the 3rd party appraisers small print you will find that the appraiser is not liable if something goes wrong. This is not an advisable situation.

 

[Caloooomi]

P.S. be aware that the lower temperature limit for CAT 3 is 0 deg C.
Air receivers tend to cool down during rapid discharge so that might be a show stopper.

Even with 316L (group 8 material)?

@the OP: If you have no one that is experienced in pressure vessel design, subcontract it.
Where in the UK are you based? Due to Brexit, Northern Ireland is different to the rest of the UK now.

 

[CuMo]

Caloooomi, now when I checked the table - you're right. There is no low temperature limit for group 8 materials.
Probably we can design vessels as low as 0 deg K then?
However - I wouldn't even use CAT 3 for something with a static head only...