P&IDs - strip vs. sheet 2

[Procman]

Our company has bought a number of plants. We are trying to standardise on P&IDs. Some plants use the scroll type or strips while others are using sheets. My personal preference is sheets but in order to convince those who have been using strips or scrolls for over 20 years I need some support! Where can I find articles or can anybody give me some good reasons why the one type is better than the other?

 

[jay165]

I don't know what sadistic bastard invented the "scroll" P&IDs, but I HATED them. Difficult to reproduce and modify originals, bulky, etc.

I haven't seem any plant designed with them since the early 70s, so I think they've gone the way of the dinosaur, but others may have different knowledge and experience.

 

[saxon]

Procman, P&ID rolls are left overs from the early days of cad when the plotters were fed from continous rolls or manually fed across a drawing board with hand cranks. All I can say is, "They're are a pain in the butt to work with and to reproduce".

saxon

 

[Montemayor]

Procman:

Both saxon & jay165 have hit the nail on the head. The strongest, most logical and forceful reason that you have to eliminate the scroll-type of P&ID is that this type of drawing is not subject to change easily in a timely and cost-effective manner.

If your plant is within the USA, you are subject to OSHA mandates and legal requirements and, as such, must maintain your P&IDs up-to-date (on a day-to-day basis) with every change, addition, or removal of equipment that takes place. This is in keeping with OSHA's PSM policy and follows their dictates on Management Of Change (MOCs - remember them?).

There was a time when the P&ID was an archival document: it was drawn and filed for reference and as a museum piece. This no longer is the case legally. The P&IDs are now regarded as living documents subject to modifications and changes, as per MOC, and must be kept at the ready for review and inspection by OSHA whenever they come a'calling at the front gate.

These legal requirements must be met and you will soon find that you must have the facility to add (& remove) sections or portions of your P&IDs. This is why the Sheet Method is the only way to go, and the "strip" method cannot function properly under such requirements.

If you can't convince your supervisors with the above information, they deserve the opportunity to pay the difference in maintaining the P&IDs.

Art Montemayor
Spring, TX

 

[katmar]

This is one instance where you can have your cake, and eat it. I have worked for years with a VERY good draughtsman who used to create great scroll type P&ID's by hand on paper. Maintenance was an issue - no argument about that.

As we moved into the CAD era we (like many other companies) broke our P&ID's up into sheets, but they were always drawn with the utility "rails" across the top and flags from one sheet to the next so that if you wanted to stick them all together into a scroll you could.

During training and commissioning sessions it is best to have a scroll type to stick up on the wall of the "war-room". But during plant construction and checking scrolls are very difficult to use and sheets are better.

If you plan carefully, you can have both!

regards
Harvey

 

[11echo]

Well I guess I have to show my age here, I like the strip P&IDs! ...But I started in this business when that was the way you normally did things, way back in the "board" days. The advantages to the strip P&IDs is that it is easier to follow lines as the lines jump from one sheet to another. Yes they are a pain trying to play with they like the old days, BUT as Katmar pointed out that if you left them on one drawing file you could continue to run lines from one sheet to another in a coherent matter. And if you only needed one sheet you can do a "window" plot and have a fresh sheet of your P&ID. I now see most P&IDs cut up into individual sheets and draftsmen, young designers, and engineers run lines all over the place, making things very confusing ...ie you have to use your finger to be able to follow an individual line and there's not the normal transition from sheet to sheet ...flow from left to right ...not the way things are suppose to happen. The unfortunate side effect of the new computer world is that it's generated a "shortcut" in learning how to do drawings ...of all types. I now see drawing packages go out the would have made my old design/drafting supervisor madder then a wet hornet! ...But now most don't care or worse don't know.
My own ranting & ravings. ...Mark

 

[nbucska]

Could anyone please tell us what the )*$^$@#@&(*&^% is
P&ID ???


<nbucska@pcperipherals.com>

 

[jay165]

Process and Instrumentation Diagram. The basic blueprint of any process flow.

Class act on your post, btw.

 

[Montemayor]

All:

Correction: P&ID = Piping and Instrumentation Diagram.

As I mentioned and inferred previously, it is the official and legal document wherein Electrical Engineers are supposed to show how a process is designed, installed, & operated safely using instrumentation, interlocks and safety relief devices. It is the documented instrument by which an operating process is technically defined and maintained in the As-Built condition in accordance with the USA government’s mandate in OSHA 1910.

Read thread124-63685 for an in-depth discussion on the subject.


Art Montemayor
Spring, TX

 

[Procman]

Thanks to all for this valuable info!

 

[SL1000]

Art mentions the USA government’s mandate in OSHA 1910 with respect to the upkeep of documentaion, in this case the P&ID. Is there an equivalent requirement in the UK/Europe besides good engineering practices and if so what is it?

Thanks
SL1000

 

[gkandy]

What is the difference between a scroll type and sheet type

 

[Procman]

A "scroll" type is a long strip. The height of the document is usually an A4 or letter size drawing, but it has unlimited length (Therefore being called a scroll).

The sheet type is a standard sheet such as A0, A1, A3 or for those Americans under you 11 x 17" etc.