P&ID 4

[Fritzfrederix]

Hi there,

Is there someone who knows or has a description whow a P&ID should look like? We've got quite a discusion about at our engineering department

bye

 

[TISM]

Need help with P&ID? try this thread first
thread798-60922
Good luck

TISM

 

[Derfel99]

The current trend for P&ID's is to have them easily readable in an 11x17 size paper, and to limit the drawing to 1 major piece of equipment (drum, column, compressor).

 

[PYLERH]

As with any drawings, the cleaner the drawing with the fewer number of jogs in lines, the easier they are to understand. Make your main process lines heavier so the main flow is more readily apparent. Leave lots of space for future details/additions. Use standard ISA SP5.1 definitions for instrumentation and controls.

 

[engpm]

There is a standard in Europe for PID & PFD: ISO 10628 Flow diagrams for process plants - General rules (replace former Germany DIN 28004 Flowsheets and diagrams of process plants).
Available from

http://www.din.de

(also English version)

 

[npf]

Hello
PID Definition :The P&ID establishes the equipment sizing and defines the piping, controls, and instrumentation requirements for the processes and operating systems including the appropriate support utilities.

For more information(P & ID symbols etc) visit

http://www.pip.org/downloads/Sample-PID.pdf

sj77

 

[nineu]

hello!
During the course 2003-2004 I have to teach a topic called flow diagrams: pictorial representations
I have no idea where can I find the rules, pics, etc for this purpuse.
If anyone could help me....
thanks a lot

 

[saxon]

Fritzfredrick & nineu, Check out ANSI/ISA Standard S5.1 latest rev. and go to the following site:

http://www.isa.org

saxon

 

[11echo]

Boy this is a sore subject with me! I've been drawing P&ID's for 27 yr.s now, I came up thru the "old school" - board drafting/big companies. Unfortunately that schooling is no longer available anymore, and the new "computer jockeys" haven't a clue HOW to draw most piping drawings (I suspect the same in other disciplines). They can run rings around me on how to use a computer, but not how to put draws together. Also I'm afraid engineers are no better! They can push numbers around but how to put a drawing is another story. Normally what happens is a engineer will "sketch" something out and pass it to the computer jockeys and in gets generated in a the standard "money see, monkey do" mode, normally not a "pretty" site!
IF you REALLY want to generate a good procedure, go to a senior designer(15 to 20 yr.s plus) and ask them to generate a procedure for you. Two things will happen, one the pressure to get something out will be off your shoulders, and two you stand a good chance of getting something that will REALLY work! My 2 cents, GOOD LUCK! ...Mark

 

[RGCook]

11echo,

In the next generation (the one after yours), process engineers and computer jockeys must be the author and creator to maintain an edge. Your analogy harkens back to the days when we scribbled our memos and report on paper and gave them to a secretary to type up.

Your options are few, adapt to the new era or be left in the past.

 

[Assumptions]

RGCook
Sounds great to be able to pass off the responsibility to the computer program. However, you are still responsibile for the result. The methods are yours. The program is there to use and the seller or creator of the program takes no resposibity for the results(In the future they make take responsibility but then one would expect that they would do the whole project as a turn-key project.) Thus one requires a method to assure that the result(s) are correct. Does one run a dummy typical program that has been proved by a back up hand calculation? How does one know that it is equivalent.
How is a checker supposed to check the work?
When two entities are involved then how does one establish that the others work is acceptable?

11echo
Agree with your point, as I understand it, that one needs competency. GIGO gives GO. Experience is a result of work. No matter how it has been gained.

My thoughts on the original post. A P&ID is the step between the PFD and construction calculations and drawings. How much information is to be presented? Debatable. If too much then one will have many revisions and run the risk of people working from an outdated document. Too little information can lead to insufficient information.

One has to find a happy medium in the industry and a company's operating procedures. (Don't forget about the insurance companies requirements)

 

[11echo]

I regret sounding the pessimist here, but to be honest I don't see how the knowledge to make "good" drawings is getting passed on! This "old school" I when through is the culmination of decades of people setting up standards and procedures on how to do things. However with the advent of the computer a "short cut" has been generated that skirts a lot of that knowledge. Yes the ability to do lettering and line work is probably not necessary anymore, but there is a "composition" to a drawing that is not being learned. What I see on P&IDs now is a spaghetti bowl of lines and symbols! A lot of the time you need your finger to be able to follow a line through the drawing. I've seen attempts to put fitting symbols at line branches, and the list goes on! Technically these P&IDs may be correct ...the sequence of equipment, valving, & instrumentation, but there is and "artistic" value too, and that's being missed. I heard an axiom the says it all ..."IF good work is not recognized, when poor work will follow"! And boy, truer words were not spoken!
I feel at times like the guy in the old space monster movie! He has seen "the monster" and is trying to warn the towns folks as to what is coming! BUT no one will believe or listen to him! (notice I put myself in the hero role here!*G*) ...I guess time will tell. ...AGAIN my own ranting & ravings! ...Mark

 

[Montemayor]

To all:

In this general discussion, I believe Assumptions has come closer to the real crux of the question. 11echo and RGCook both have valid and important concerns. However, the reality of what P&ID's should reflect are:

1) They should be readable and incorporate all the ACTUAL piping and instrumentation existing in the actual process (or unit) IN AN ACCURATE, AS-BUILT MANNER.

2) They should be interpreted, defended or challenged by engineers during the required HAZOP(s) that legally have to occur before any unit is commissioned or changed.

3) They should be constantly under a controlled state and be subject to PSM (Process Safety Management) and MOC's (Management of Change procedures).

4) They should be compete with required vessel and instrument identifications and safety ratings relative to potential hazards (such as set pressures, switch positions, alarms, etc.)

What I am stressing here is that the P&ID is the INSTRUMENT OF RECORD as far as the USA government (through OSHA) is concerned -- and they are CONCERNED!! Regardless of how we all feel about government meddling in free enterprise, the truth of reality is that operating engineers (especially Plant Managers) are legally responsible to the government in the US for safe operation of all processing plants - PERIOD! If we do not comply with OSHA's requirements, they will (& can) pad lock the front gate. They can also put plant managers in jail for not complying.

I'm not preaching fear or revolt; I'm stressing the importance of generating and maintaining accurate, readable, and efficient P&ID's. Notice that I'm not even mentioning esthetics. I am presuming a PROFESSIONAL quality, which preempts and demands everything 11echo is correctly concerned about. I cannot visualize a P&ID generated (or modified) without an engineer being directly involved (& responsible)! How could this be possible when the drawing(s) are destined to be subjected to a HazOp? Any organization that tolerates this deserves what it gets - which will be the wrath of OSHA. As an example, it is not rare today that major companies (such as DuPont, etc.) demand that all P&ID's be stamped as correct by a registered engineer. This is not passing the buck, nor posterior protection; rather, it is to ensure that the enterprise is taken seriously and is covered by liability - where this is all coming from. As engineers we are responsible. And this won't go away. P&ID's and their quality are important - but more important is their accuracy and their detail that allows control of the operating process for safety reasons.

It's not about a drawing; it's about telling a detailed, accurate, engineering description of what's out there and how it is controlled.


Art Montemayor
Spring, TX

 

[209larry]

Fritzfrederix,

P&IDs in Autocad with well-engineered block attributes(visible and invisible) can save up to 65% of detail engineering manhours and gives a better accuracy than 'manually' cross-referenced construction drawings and documents. With a mouse click you can retrieve and generate equipment list, line list, instrument index, I/O list, alarm settings, piping bulk materials except elbows, vessel nozzle schedules, PID drawing index of 100 drawings in just 1 hour. Using VBA you can fill in extracted data into your equipment & instrument data and calculation templates.

209larry

 

[zqew05]

O&ID's should be a controlled document, meaning any changes should be submitted through the MOC process. There are people out there who make arbitrary changes because "that's how I like it done". Or is it called Preference Engineering?

 

[olmedo]

You can buy softwares that are designed to draw P&IDs.It includes library of symbols and nomenclatures.

 

[abcmex]

After reading this thread I was very impressed. I thought: WOW there is only one standard for PID's ISO 10628 Flow diagrams for process plants , see above). I know ISA has one instrumentation standard but they are more concerned about the instruments and control loop description.

Still I was suspicious because the PID's from USA that I saw all had a certain similitude that, I assumed before, should come from a standard.

Now the smoking gun.
ANSI Process Flow Standards. ASA Z32.2.3-1949. ;-)

 

[Mike6158]

From what I've seen, 11echo's lamentations are on the mark. I learned how to generate a P&ID from "old school" draftsmen back in the late 70's. One of them is still in the business and he has transitioned to CAD (and loves it by the way). The problem, as I see it, with a lot of today's draftsmen is that they fail to "let the drawing flow". By that I mean use simple tenets like trying to bring flow into the drawing from the left and exit the drawing to the right. While not always possible using this kind of standard ensures that the drawing "flows" to the user. When I draw (CAD) I used ledger lines to align horizontal and vertical lines to from equipment. This results in a symetrical drawing that is easy to interpret (even if the lines do not connect to the same piece of equipment). The minds eye likes symmetry. Too many people do not spend the time that is necessary to give the drawing symmetry and that makes for poor P&ID's.

 

[FrancisL]

Speaking as an Automation engineer who does a lot of work with P&ID’s from various companies I can state that there really is no consistent standard.
For example some people show all the System inputs and outputs in some form on the P&ID, others do not. Some use packages like InTools to extract the IO List but this is rarely complete either in having all the IO or all the fields such as the IO Address

Some carefully arrange the P&ID’s to only show one 'Unit' (in the S88 sense) others put as much equipment as possible on a P&ID and when it is full start the next one. The worst I have seen (lots) have equipment split across two or more P&ID’s

Some try to make flows go left-right and others do not. Often the P&ID is used by the automation supplier as a basis for the process graphics. But P&ID's are mostly drawn with no thought whatever for operation or procedural logic. And the resulting graphics are not IMHO good.

Another thing is that often a process has several virtually identical equipment items (eg Several batch reactors) but instead of drawing it once they draw the same diagram each time. Of course the tag numbers on each must be different but this can be achieved by having one diagram and a good Unit based tag numbering scheme.
By the way, tag numbering schemes are often as inconsistent as P&ID's, - but they are topic in themselves

 

[pmover]

all,

please note this thread: thread403-76603

Art M. posting is exactly what i learned/practiced, being in the oil & gas industry. p&id's are the bible and are frequently referred to by design engineers in the epc business.

in other mentioned thread, i thank wilg for clarifying the differences and in this thread, FrancisL observations are also noted.

lately, having reviewed "incomplete" (meaning not to the detailed level i'm accustomed to nor including spec requirements) hvac drawings/schematics for construction purposes does not provide a "degree of confidence" that required equipment or features are included in system.

different industries have different meanings or interpretations for same terminology. communication is key in understanding the terminology used in other industries, other than primary practice.

thanks and good luck!
-pmover