P&ID at IFC level

[Buchi]

Hi gangs,

i am interested in knowing the difference ( in terms of detailing) between the P&ID generated at the Basic Engineering stage and that generated at the detailed engineering stage and issued for IFC.

cheers,

Buchi

Buchi

 

[saxon]

Buchi, I think you're confusing the difference between what is known as a PFD (process flow dia.) and the P&ID.

Hope this helps.
saxon

 

[pmover]

generally and depending upon engr firm...

a PFD is initially created establishing the main process systems (i.e. flows, pressures, temps, equipment, etc.). from that PFD, a P&ID is generated and may be referred to issue for design (IFD) or similar. this set of P&IDs are used by engrs/designers in establishing the basis of design and for conducting the design. during the design process, project team members continually and have a responsibility to update and maintain a master set of P&IDs. The case may be where another issue (rev 1 of IFD) of P&IDs are generated to capture handwritten comments/updates on master set of P&IDs.

Once the design is completed, the P&IDs are then issued for construction (IFC). at this stage, the construction superintendent maintains a master set to incorporate as-builts. there must be open communication between field and design engrs/designers to ensure proper design of facility and maintaining a master set of P&IDs.

i trust this concise description helps you.

good luck!
-pmover

 

[MortenA]

one major item is that you CANT have "holds" on a P&ID issued for construction.

Best regards

Morten

 

[tickle]

Morten

I have in the past issued a variety of documents with holds at the IFC stage, including P&ID's. At the time I believed I was correct in doing so and can now provide arguements supporting the issuing of a P&ID with a hold on it.

For example, the hold may be actual value at which a level alarm from a transmitter is set. This would have no bearing on the actual construction and would be confirmed during commissioning.

I would be pleased to hear your opinion on why a P&ID cannot be issued with a Hold.

I am not trying to shoot you down or ridicule you, I am just interested in the rationale behind your statement, whether I am misreading the intent of your post, or whether you are referring to a particular industry sector. Also I suppose differnt people expect to see different items on a P&ID.

Thank you in anticipation

 

[pmover]

in the event of issuing P&IDs with holds, the engr firm (or issuer of dwgs) needs to explicitly clarify to receivers of P&IDs the justification or explanation of holds.

i've received and have been with firms that have issued P&IDs with holds. yes, it may cause some apprehension and communication is important is this mater.

good luck!
-pmover

 

[mgp]

These two threads might be of interest to you too

thread378-21094
thread798-61448

With respect to the HOLDS question I think that in the ideal world Morten is correct but in reality it is quite common that P&ID's are issued AFC (or IFC) with Holds, provided the unresolved item is minor compared to the overall P&ID content as for example mentioned by tickle.

After all no Project Managers will accept holding back a whole construction package if a minor detail, e.g. the size of a thermal relief valve, was not resolved. Of course one must be sure that the HOLD (when resolved) will not affect the released work.


regards
Mogens

 

[MortenA]

Tickle

You may be right - some companies provides this info on P&IDs - some dont - however since they are issued "for construction" i would assume this included control loops.

You say that a level alarm wont influence construction but what if its a level alarm on a stand pipe or a swith in a specific nozzle?

I dont think that it is just in an "ideal world" that this rule should be kept because if its a minor thing - why not just get rid of it before issuing? And if its a major - how will you construct something whit this unsolved?

Mogens and I have worked together and we might have issued for construction with holds? Sometimes its just impossible to get the client to forward the info you need to resolve a HOLD and issueing might be the thing that triggers it (but maybe also some sour remarks ;-)

Best regards

Morten

 

[smckennz]

The basic P&ID starts by showing the major equipment items and the interconnections between them. In many cases the first draft may be a tracing of the PFD. Items not shown are typically equipment numbers, pipe sizes and materials, support services, instrumentation, and controls grouping.
The style of PFD determines the amount of information to be added. The block diagram type of PFD which is used to determine the mass and energy balances may not show equipment such as pumps; only process material inputs and outputs.
The functional type PFD will show discrete equipment, but normally only what is required for the process and not what is required to serve the process. For example it may show a feedwater pressurising pump but may not show the feedwater distribution pump, supply tank and borefield. Or the water filtration plant. Or the gondola required to take the copper sulphate to the top of the mountain.

Basic P&IDs are characterised by a lot of blank space on the page. A good set will not change shape as the detail is added; the blank space gets filled in instead. A bad set will have equipment moved and pages added.

P&IDs are a living, breathing thing and normally continue to change as the job progresses.
If the P&IDs stop changing, its a sure sign that the designers have run out of money.

Cheers

Steve