P&ID's A.F.D. - How complete are they

[mgp]

We have a discussion about the various development phases of a P&ID, especially when going from one design phase to another.

The terms "Approved for design" and "Approved for Construction" are often used as milestone terms, however the ecpected level of completion is not always common understood.

Is anyone able to make a proper listing of what is included/excluded according to common engineering practice - or better - does anyone know any Standards or Recommended Practices which clearly defines these levels?

My own understanding:

Approved for Construction P&ID's are finalised and released for fabrication except where any (few) outstandings are surrounded by Hold clouds.

Approved for Design P&ID's are more tricky:
Design is completed with main equipment & lines sized, but design may be outstanding for e.g.
relief valve sizing
vendor data for valves & equipment
vents/drains

Or am I completely out of line?

Regards
Mogens

 

[TD2K]

I think that's pretty reasonable Mogens.

IFC P&IDs should be as you said just about completely finished. IFD wouldn't have vents and drains for high/low points as a lot of those get added during detailed design when pipe routing is laid out. Most of the other work should be complete except where you are waiting for vendor data or vendors are doing packaged equipment and all you have is a box essentially.

 

[MortenA]

Mogens

Approved for construction should not have HOLDS. How could you construct with a hold? The only thing would be if the items were to be installed at a later phase and therefore not required. E.g. some types of instrumentation/process control computers could be installed after finalizing piping and could therefore wait a little.

Best Regards

Morten

 

[grafter]

Mogens,

I would be interested to know if your need for clarification of "Approved" is based on contractual argument between Contractor and Purchaser?

Regards,

Brendan.

 

[mgp]

Hi Grafter

Yes in some sense it is based on a contractual agreement.

We have a typical set of project phases:
Conceptual Design, Basic Design, Detailed Design, Construction and so on. The different design phases may, (and may not) be put out for tender by other design contractors, and our discussion goes about that at a certain stage P&ID's shall be "Approved for Design". This will - when subcontracted - be a contract document, but we want to make sure that everybody has a common understanding of this term, preferably in line with the rest of the industry.

To Morten
I agree that "AFC" should not have holds, but it is almost never an ideal world where e.g. all vendor data is available at construction start. Most schedules does not allow you to wait for this provided the majority of design is ready.

regards
Mogens