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Do you show flanges on a plant P & ID?
18

Do you show flanges on a plant P & ID?

Do you show flanges on a plant P & ID?

(OP)
Ok, we're having a debate internally here about what is "normally" done on a P & ID.

Do you
A) Show deliberately a little vertical line next to each flanged valve to indicate it's a flanged valve or
B) Assume all the valves in a plant are flanged valves.

If B how do you show when it is deliberately a welded end valve you want (e.g. last valve going into a long gas pipeline)

I've seen both ways and A really annoys me as you get little lines all over the place and then you can't see it or it gets lost in all the other data.
We're talking fairly basic P & IDs here, not the all singing all dancing "intelligent" P & IDs.

Spool pieces, blind flanges on e.g. drain valves are shown but "normal valves"?

Answers on a postcard please....

Thanks, LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

No. Use a note to detail anything out of spec or unusual.

Piping Design Central

RE: Do you show flanges on a plant P & ID?

Agree with Gator.

A Piping and Instrumentation Diagram - P&ID, is a schematic illustration of functional relationship of piping, instrumentation and system equipment components.

A Piping and Instrumentation Diagram is not a fabrication drawing.

RE: Do you show flanges on a plant P & ID?

The most common approach I have seen so far is to indicate flanges and their size on all vessels and all valves. For flanged connections between two piping segments this was rarely indicated on P&IDs, but also not uncommon.

Welded valves have their own symbol in the P&ID legend and they are distinctive on the drawings.

With Process and Safety background, I am a big fan of capturing this kind of information on P&IDs. When defining various unsafe scenarios, seeing the number of flanges (as potential leak paths) and at the same time being able to determine isolatable inventories at the P&ID level only, is a tremendous thing. Having this information on P&IDs also helps in defining isolation philosophy for turnarounds (where to insert a spade or a blind flange), doing troubleshooting of the plant operations, defining piping specification breaks, HP/LP interfaces etc. I think the reasons for providing this information on P&IDs are numerous.

As for the clarity of drawings - a proper P&ID should not be congested and if rules of good practice are followed (e.g. one vessel per sheet etc.) showing flanged connection on the drawings should not really affect their clarity.

Dejan IVANOVIC
Process Engineer, MSChE

RE: Do you show flanges on a plant P & ID?

We dont show spool breaks but we show other flanges (vessels, valves, pumps etc.)

RE: Do you show flanges on a plant P & ID?

It's a bit ironic that today you are asking about showing flanges after I had a similar discussion about trying to get you all to show major valves just last year.

My opinion is that if something is important, show it, however it usually is not necessary to show flanges, especially since a PID should have adopted different symbols for flanged and weld-end valves, if indeed it would be important to show the difference.


On plant drawings made by major engineering companies, the likes of Flour, Brown & Root and Stone & Webster, etc., back in the day, proper piping plans and profiles were made. On those flanges were shown. Two lines were made for pipe only when D>12", with pipes smaller than that represented by one centerline line. All valves were shown as above as well, except with valve lengths and flange widths to scale.

Don't see why the argument. Nobody's drawing them in pen & ink on vellum. Either way, it's JUST A CUT & PASTE!

If all valves are flanged, then no, a simple general note, "All valves flanged, except as noted otherwise." should do the trick.

RE: Do you show flanges on a plant P & ID?

It DOES HELP on P&ID's to know what joints can be broken for temporary fittings, flush or hydro connections, Backwards flow attachments, blind flanges, or blank connections.

The "dot" and "line" connections in Big Inch's sketches above are the usual practice, and they should be encouraged.

RE: Do you show flanges on a plant P & ID?

3
Do not show Flanges on P&ID's unless there is a compelling reason.
Show Flanges at Vessel Nozzles only where there is an installed Spec Blind.
Show Flanges for inline Flanged Valves only where there is a Spec Blind.

Do not show Weld Dots on any P&ID.

The manner of connection (Flange, Threaded, Socket-weld, etc) of a valve in a line is covered by the Piping Material Line Class Specification and the line size.

Sometimes its possible to do all the right things and still get bad results

RE: Do you show flanges on a plant P & ID?

pennpiper is the respected senior authority on this subject ...... Bravo !

Ummm ... No one has mentioned the PIP P&ID Industry standards ????!!

MJCronin
Sr. Process Engineer

RE: Do you show flanges on a plant P & ID?

I agree that weld dots are not normally shown on PIDs, but if they are important for some reason, they certainly could be.

RE: Do you show flanges on a plant P & ID?

Normally we do not bother about this if process has shown flanges or not, as anyhow for detailing we need to go to the relevant material classes. And as BIMR put it above, P&IDs are not fabrication drawings only schematics though I have seen clients asking for (to consultant process engineer):
1) Your P&IDs must show lines from east to west so we can recognize from the P&ID itself. (I don't know how it was solved finally!!!!!).
2) Your lines should be showing the road crossing (going down and then coming out)....

RE: Do you show flanges on a plant P & ID?

(OP)
Gentlemen and I think sadly it really is all gentlemen unless anyone tells me otherwise, thank you for your valued input. As I expected there are two views on this and to summarise and respond to a couple of points,

Dejan, thanks for the links and the symbols sheets etc

People seem split about 50:50 on this.
One problem I now have is that the legend sheet I'm working to as we're designing an add-on to an existing plant, does not appear to have any symbol or way of identifying if a valve is welded or indeed one weld end, one flanged. I've searched the sheet and looked at some P & IDs where this should be and can't see anything there or any symbol or note or type of valve to indicate a weld end valve. Maybe they don't have any, but it seems surprising. The piping spec is non descriptive about flanges or welds and doesn't seem to have any options on this, but maybe that ends up buried in the valve schedule.

It think the thing to do is to generate a symbol for a weld end valve - does anyone have an example? - and then assume all are normally flanged.

Flanges on vessels, flanges where you specifically need to show them (removable spools, spectacle blinds etc) are in there and seem a good idea.

The symbols BI has loaded to me are more isometric piping drawings to me and I've never seen a weld dot on a P & ID.

BI- the valves you refer to were valves on a PFD, but that's another post/story.

Thanks again for the valued input
LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

Dear All,

The trend is changing because of intelligent P&IDs where MTO of all the pick-able (except Pipe & Elbow) items is now started coming from Intelligent P&IDs.
You will see these changes in approach of P&IDs are now becoming spec intelligent to account for Flanges as well.

Working on such project currently where this is being observed. Great utitlity if you look at MTO aspect of this change.

Thanks & Regards,
Abhijit

RE: Do you show flanges on a plant P & ID?

I was just going to mention the same thing. Great post Abhijit.
One hardly ever sees plans and elevation drawings anymore. That's where the MTOs used to come from, but no longer.

RE: Do you show flanges on a plant P & ID?

Quote (LittleInch)


The piping spec is non descriptive about flanges or welds and doesn't seem to have any options on this, but maybe that ends up buried in the valve schedule.
LI

The PIDs I've dealt with generally do not show flanges. Only at vessel connections. However many times a valve or random component does get drawn with flanges. It is quite inconsistent depending on the age of the PID and who drew it... always a challenge keeping things consistent across the plant(s).

Per your sentence I quoted above; Our pipe specs are very detailed on what valves/piping components are allowed to be flanged/welded/threaded. The PID indicates the pipe spec on each process line. From that I generally assume it follows said spec. Usually any anomalies are called out with a Note.

RE: Do you show flanges on a plant P & ID?

Drawings are just a means to convey information.

If the people actually using the P&ID aren't going to need to differentiate a flanged valve from a welded flange for their purposes then don't bother showing them.

If there is a good reason to show them then show 'em.

I lean toward the former. But when it comes down to it, all that matters is that the information needed is conveyed.

RE: Do you show flanges on a plant P & ID?

(OP)
I agree, but equally established conventions are also useful.

The issue partly arose because someone who was used to seeing flanges identified on each valve, got a P & ID which worked the other way and then assumed, without seriously thinking about it, that all the valves were welded.

I still haven't got any feedback on how people show welded valves if the convention is to not show flanges. - Anyone?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

The primary purpose of the P&ID is effective communication between process and piping design. I've seen various other groups in meetings/design reviews asking for non-process things to be included but doing so only adds to the workload and adds more contributors to the workflow.

As mentioned upthread, valve particulars such as end connection type are detailed in the valve specs.

Sometimes smaller companies/suppliers can get very detailed on their P&IDs since this may suit them better but they're typically not issuing dozens, maybe hundreds of drawings for one project and likely have only a few people using the P&IDs, so communication is simpler.

Of course, with CAD, it's tempting to say, "Hey, why don't we just include X, since everything's digital and easy to add or revise?".

What was the reason to propose showing flanges in the first place - for maintenance? Purchasing/MTO? Safety?

Piping Design Central

RE: Do you show flanges on a plant P & ID?

(OP)
Gator,

The initial issue was the ease of the piping designer, but as others have noted above, p & ids get used for lots of other reasons as the plants goes into operation and modifications.

TBH, we're probably in the smaller company mode and as pipeline engineers our plant processes are relatively simple. At most we issue tens of p & ids, not hundreds.

Thanks for the input.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

My opinion - yes, they should all be shown - there can be some serious installation errors otherwise. This is the job of the process and piping engineers on the design project.

RE: Do you show flanges on a plant P & ID?

2
The interesting, and frustrating, thing about working for many clients from many different companies is that you see how different people tackle the same problem. Sometimes there are good reasons, and sometimes (very often) the reasons behind what is done (what is on the legend sheet) is long forgotten or only known partially and by a few.

Some companies' P&IDs show every valve that gives a person access to the process fluid. Personally I agree with that approach. Others find that showing instrument blocks, bleeds, vents, drains, equalizing valves etc. adds unnecessary complexity and makes the drawings too difficult to read, and they imply all these valves by means of a separate document such as a set of instrument installation details. Personally I hate that, both from a construction and operation point of view. I take it to the extent of even showing (as a symbol, without tags), the suction and discharge check valves in PD pumps etc. If you want to analyze how something will flow, you need to know what is and isn't in the way.

Some companies give each item on the P&IDs (including most valves) a unique tag number, i.e. HV-1234. Others only give valves what amounts to a model number or spec call-out ID and fail to give them a unique identifier. Just try to write an operating or maintenance procedure using drawings like those...Others try to include both, and to differentiate valve types to an extreme degree using different symbols. Sometimes they run out of space or end up with twice as many P&IDs to fit everything. I prefer to give every valve and instrument a unique tag number and then give the details in a separate bill of materials or the like, though the "model numbers" right on the drawing can be very handy. As to hand valves, at an early stage in a project, valves are of only three types: they are either block valves, throttling valves or check valves. The detailed symbols, if they're necessary, to differentiate a ball from a gate etc., go in after selection is complete.

The same goes for controls: some try to duplicate the entire cause and effect, including linkages, on the P&IDs. That's typically a failure. Some kind of numbering system referring back to the cause and effect just works better.

And then there's the OP's original ask: piping details such as flanges and other split/breakpoints in lines and equipment. The best approach is what Pennpiper suggested- to show them when they're need to understand function. We usually show flanged nozzles and body flanges on vessels., flanges for removable spoolpieces, where components such as spectacle blinds, static mixers etc. are to be inserted into a line, where a line joins a flex joint or hose etc. Attempting to show every pair of flanges, coupling or union or Victaulic coupling etc. on a line can result in a set of drawings which are needlessly garbled. P&IDs aren't isometrics or pipe routing drawings.

Weld dots and other shortforms from isometrics or routing diagrams do not belong on P&IDs in my opinion.

Smart P&IDs are centralizing the information and making errors between documents less frequent. That gets rid of the need for a lot of checking, but that checking sometimes catches other things that people miss. On balance it's a good thing, if not taken to an extreme.

RE: Do you show flanges on a plant P & ID?

Exactly why standards are not useful all the time.
The best practice is to show something whenever you think you need to show it.

RE: Do you show flanges on a plant P & ID?

Sometimes there is a distinction between P&ID and PFD drawings, the valve type is certainly shown on the PFD ( process flow diagram ). Sometimes the drawings are combined, but called P&ID.

RE: Do you show flanges on a plant P & ID?

Isn't there always (not just "sometimes") a distinction between P&IDs and PFDs though? PFDs typically won't show valves that are assumed to be present (blocks and checks at pumps, for example) unless they are critical to the overall process.

Valve types are always shown on P&IDs, and the concept of "installation errors" due to wrong symbology on P&IDs I don't really understand unless it relates to bi-directional flow or some other unusual cases. I would hope that such "unusual cases" are monitored separately as happens with critical lines for stress analysis.

Vents and drains on P&IDs are only to be shown if they are critical to normal (or expected upset) operations. Locations of HP and LP vents and hydrotesting vents and drains are often better left to the field* to determine since the P&ID designer cannot be expected to know the final physical piping routing.

moltenmetal's comment, "P&IDs aren't isometrics or pipe routing drawings" is a very good one.

Paul


* Fab shops will have input on this if testing is not performed on site.

RE: Do you show flanges on a plant P & ID?

(OP)
Thanks for all the comments, I didn't expect quite so many comments but it's clearly something that varies a lot with different sets of usage.

Moltenmetal I agree completely with your points about tagging. I much prefer lots of individual tag nos even for manual valves.

If were taking this a bit further, in my opinion and I've found it in a few company specifications, is the number of valves and equipment you show on a PFD. I always argue that the only things you show on a PFD are things which affect the fluid, so pumps, heaters, HXs, control valves, but no other items which don't change pressure temperature or composition such as isolation valves, esd valves, pig traps.

I come across a range of opinions on this and would like to know if I'm in the majority or not??

Thanks, LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

We put piping vent and drain valves on the as-built P&IDs.

Instrument block/bleed/bypass always go on our drawings, but as I noted we have some clients who don't want them on there.

A PFD and a P&ID are as different as a P&ID and an isometric drawing. A PFD only shows equipment and main control loops, and stream and equipment tag numbers.

RE: Do you show flanges on a plant P & ID?

Quote:

I always argue that the only things you show on a PFD are things which affect the fluid, so pumps, heaters, HXs, control valves, but no other items which don't change pressure temperature or composition such as isolation valves, esd valves, pig traps./

IMO, as you already know, valves that control flow are not limited to "control valves". On/Off valves also control flow and can be especially important in pipeline PFDs. In fact in some systems (esp. pipelines) they just might be the only kind of valves installed at all.

RE: Do you show flanges on a plant P & ID?

(OP)
I can appreciate the point but where do you stop. The whole point to me of a PFD is to show what is supposed to happen during operation. It after all a Process FLOW diagram, not a process no flow diagram...

I usually like to include a control schematic diagram to illustrate how the on/off and other parts function, but keep the PFD as simple as you can and assume the system is working as it should be.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

"I still haven't got any feedback on how people show welded valves if the convention is to not show flanges. - Anyone?"

Bueller here. Ha We don't show welded valves on P&IDs. The P&ID line number shows the line class/spec and that spec tells you the valves are welded.

Now. If you have a one-off, for example if you need a buttwelded valve in a line that is of a spec that normally uses only flanged valves, then we would show a spec break OR put a note on the drawing where that BW valve goes.

For flanged pipe, you don't show flanges on the P&ID. However, we will show flanges where they are important for the process, e.g. break-out spools, future tie points, future spool pieces where a meter will be added, etc. As was said above, one of the main uses of the P&ID is the formal communication tool between the engineer and the designer. If you want a flange pair in the line you need to make it on the P&ID so the designer knows to put it in for you.

A great question; one that always engenders a ton of debate, although it shouldn't, in theory.

RE: Do you show flanges on a plant P & ID?

Well I think it can be very important process-wise to know that you're not going to be continuously blending gasoline with jet fuel, for example.

RE: Do you show flanges on a plant P & ID?

Often valves are annotated NC or NO (normally open or closed) if there could be some confusion about what's supposed to be going where.

RE: Do you show flanges on a plant P & ID?

KernOily,

With respect to adding a valve or other piping component which is not included in the piping class it would be treated as a special piping item and assigned a tag number e.g. SP-XXXX.

RE: Do you show flanges on a plant P & ID?

(OP)
BI - In that instance then yes, showing a valve on a PFD would be required because without it the composition would change. Otherwise no (IMHO).

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

MickMc - Thanks. I've not seen this myself. Typically in my experience, SP numbers are assigned to things like: expansion joints, ball joints, startup strainers, etc. I've always seen a spec break or a note on the P&ID when using out-of-spec components, just the way God and Mother Fluor intended. Ha Probably depends on the owner's preference and the P&ID lead sheet for the particular project. I could see using an SP number for an out-of-spec valve and I wouldn't get heartburn about it if the team wanted to do it that way.

RE: Do you show flanges on a plant P & ID?

You show no special symbol for welded end valves or any valve (other then type i.e ball, gate, globe, & etc.) the piping spec for any line "should" dictate what type of valve it is (flanged/weld end/screwed/SW). I agree with Kern oily on use of a SP number for any "odd-ball" items that may be generated.

RE: Do you show flanges on a plant P & ID?

3
Sorry guys ("guys" in the all-inclusive, gender-neutral sense)...

If *I* draw, or have drawn for me, a P&ID, then it is my complete expectation that to the extent practical, every flange is shown, no exceptions. With CADD today, and construction isometrics and bills of material automatically generated from the 3-D model, there is absolutely no excuse (in my mind) why this cannot or should not be so. When I do as-building and walk-downs in the field, I use the P&ID. It is my expectation that, as I walk down a line from point A to point B, every branch, valve, bleed ring, vent, drain and flange can be seen and "yellowed out". When this is not the case, I mark the P&ID such that this is indeed the case. I've been doing things this way for 34 years, and I am going to continue to do it this way through to my retirement. I don't subscribe to, nor do I agree with, any rationalization that P&IDs get too busy to show these details; if that's the case, split the P&IDs across enough sheets in order that these details *can* and *will* be shown. I also strongly push for every valve to be denoted by its corresponding valve tag number on the P&ID; I believe that final selection of manual valves is an *engineering* function, not a *drafting / design* function. I want to be able to do a 100% accurate valve count in support of BOMs and RFQs and RFPs directly from the P&ID.

I do not subscribe to, nor do I agree with, the assertion that the P&ID is not a fabrication drawing. WRONG! - It *IS*.

I don't always get things the way that I want, but I've been in the EPCM business for more than three decades and I have never willingly settled for less than what is described above, and I strive for as close to 100% accuracy on the P&IDs as I can get. For what it's worth, everyone I've ever worked with in Canada - employers, clients, producers and EPCMs alike - appear to share my expectations.

In short, if you know the thingy exists, and it is possible to show the thingy on the drawing, then show the thingy on the drawing. Anything less is a measure of laziness, complacency, and lack of due diligence.

RE: Do you show flanges on a plant P & ID?

When I do as-building and walk-downs in the field, I use the P&ID

RE: Do you show flanges on a plant P & ID?

Dear SNORGY this stands true for you at field however, this isn't stands true when Engineering is being done. P&ID is considered as a mother document for Piping guys to do their design for Piping.

Process designers/engineers are not in the position to understand the piping material specification like different ratings, end connections requirements etc.

As you have mentioned above, if you are using P&IDs for tracing lines from point A to B in the plant, you should also take piping as built isometrics with you to get 100% details for all the items in each & every line you are tracing.


What we also can do in the engineering phase is that update P&IDs to the as-built state based on the as built isos. Does that makes sense?

Dear all, let's discuss this topic further to fine tune the understanding we have about this important topic.

Thanks & Regards,
Abhijit

RE: Do you show flanges on a plant P & ID?

cjabhijit,

Sorry, I disagree. Process Engineers or Systems Engineers or Project Engineers or P&ID Engineers - whichever engineers draw the P&IDs - in my mind are responsible to make sure that they are in complete alignment (to the maximum extent possible) with the piping drawings or isometrics before they get to the field. If the guys doing the 3D model want to add flanges, delete flanges, change valves etc. then the appropriate thing for them to do is to communicate those changes via a master P&ID stick file prior to IFC.

"Process designers/engineers are not in the position to understand the piping material specification like different ratings, end connections requirements etc."

I believe, personally, that anyone fitting that description is not adequately competent to draw a P&ID.

RE: Do you show flanges on a plant P & ID?

Hey Snorgy, we're in alignment on just about everything EXCEPT showing every flange. Perhaps if you use the proviso, "...on every line greater than 2" NPS", your rule about flanges might make sense to me. But I've never had a client who insisted on this.

Not to compare resumes with Snorgy, but I've been working and living in Canada a long time too, though most of my projects aren't in Canada. It's just another piece of evidence that skilled and competent people can hold strong, and divergent, opinions about the only right way to do something, and yet there may be more than one "right" way.

I'm curious what do you do with the other types of couplings or joints that give someone access to the process fluid? Do you show compression fitting joints? Threaded unions? Victaulic couplings? Tri-clamp connections? Our piping systems aren't all piping, and when they're piping, it isn't all flanged... We follow the same rules with those connections as we do with flanges: we show them when they're needed to understand function, and don't show them otherwise unless a client insists.

FYI I never said that a P&ID isn't a fabrication drawing: I said that it is neither a routing nor an isometric, which is pretty obvious. When flanges ARE on our P&IDs, it's a signal to our piping designers to ensure that they're present- because they have a necessary process function.

Your comment about the minimum level of competence of people drawing P&IDs resonates strongly with me. Too many people attempt to eliminate the need for basic competence in the design of pressure retaining equipment by replacing that competence with pipe specs. We see that in many of our clients and we find it both frustrating AND dangerous.

RE: Do you show flanges on a plant P & ID?

As BigInch posted, if something is important, show it, however it usually is not necessary to show flanges.

Fabrication drawings, also called machine drawings, are principally found in and around machine and fabrication shops where the actual machine work is performed.

P&IDs are usually designed to present functional information about a system or component. Examples are piping layout, flow paths, pumps, valves, instruments, signal modifiers, controllers, etc:



P&IDs do not have a drawing scale and present only the relationship or sequence between components. Just because two pieces of equipment are drawn next to each other does not indicate that in the plant the equipment is even in the same building; it is just the next part or piece of the system. These drawings only present information on how a system functions, not the actual physical relationships.

Because P&IDs provide the most concise format for how a system should function, they are used extensively in the operation, repair, and modification of the plant.

From Department of Energy Fundamentals Handbook

http://www.purduecal.edu/cpmi/NSF%20Courses/ECET-4...
ENGINEERING SYMBOLOGY, PRINTS, AND DRAWINGS



For those things that are deliberately left off P&IDs for the sake of clarity, other documents are used to provide the details. Common documents that serve vital support functions to P&IDs include:

Piping and material specifications. Here, you can dig into all the gory details about materials of construction, gaskets, bolts, fittings, etc. for each of the services.

http://www.aiche.org/chenected/2010/09/interpretin...

Examples of PIDs':
http://www.aiche.org/sites/default/files/ChEnected...

"If you compare lead sheets from a few dozen companies, you will find that 90% of them are pretty much Copy | Paste. For that last 10%?, there can be distinct differences and company-specific conventions used that are not obvious on P&IDs."

"Clearly there can be a lot of information to show on a P&ID. And for this reason, there are various degrees of detail that a particular company will generally choose to show. There is no formal standard for the various amounts of information a P&ID must include. Rather, it is left to the discretion of the engineers involved. In terms of detail provided, my opinion is that a good P&ID will strike a balance of "clarity without confusion". If you can't see the process for all the symbols, then it's probably overdone. On the other hand, if you can't even discern how a pump may be operated or what interlocks may exist, then you probably need to embellish it a bit."

RE: Do you show flanges on a plant P & ID?

Dear Snorgy, I value your opinion however, would like to highlight how it is done.

I strongly believe that P&ID can't cover all the items which are required to fabricate the line at site otherwise why Piping would consume so many hrs to generate all the deliverable like Plot Plna, Equipment Layout, Piping GA, Isometrics, Material specifications.

Pls reconsider your opinion considering all the inputs being received in this topic.

P&ID just can not cover all the items.

Example- If there is Epoxy lined Piping & the lining requirement is to have flanged connection every 12m. This is doesn't mean P&ID will cover all these flanges for say some 200m of run of this lined piping. Does that makes sense?

Thanks & Regards,
Abhijit

RE: Do you show flanges on a plant P & ID?

In my opinion, all flanges should be shown on P&IDs (Piping & Instrumentation Diagrams). Snorgy's commentary is spot on. The P&IDs are the bible and are the foundation for all other construction/fab drawings.

We also typically label the class rating (e.g. 150#, 300#, etc.) on every or flange joint in our P&IDs, just for the sake of consistency. It's amazing how often contractors or clients will mistake spec break locations.

On PFDs (Process Flow Diagrams), showing flange symbols would be extraneous and are never shown.

RE: Do you show flanges on a plant P & ID?

Consistency is a good reason not to show all details on P&ID's. If the same item is needlessly shown on multiple drawings, it is a headache to have to go through the entire set of drawings to make sure that everything is consistent throughout the set.



RE: Do you show flanges on a plant P & ID?

Hi,

Not all flanges are required to be shown in the P&ID. If a flange is used as a mechanical joint to connect two pipes, it need not be shown in P&ID. Flanges connecting to equipment (which includes valves) are to be shown clearly in P&ID; adopting a legend which can discriminate a welded valve to a flanged valve can solve the purpose.

RE: Do you show flanges on a plant P & ID?

(OP)
WOW,

I only expected 4 or 5 replies, not 45, so many thanks to all those who have contributed here to a very interesting exchange of views.

I've flip flopped a bit reading some of these comments, but finally gone back to my start point, which is that, all things considered, showing flanged valves as flanged valves on a P & ID is ultimately easy for a CAD designer, even in simple P & ID blocks, never mind the new intelligent ones, prevents you having to check valve tables and piping specs which may or may not tell you whether flanged valves are used and is useful during piping drawings, fabrications and operations.

Yes, you always need to have the legend sheet available, but showing flanges at flanged valves, which is where this post started, to me now seems to done by enough people with good reasons why to make it my default, if I actually have control of the legend sheet - which isn't always the case.

Someone said if I had a spool which was broken into flanged section to allow easy removal or needed for manufacture then yes, I would either show all the flanges or show one spool piece then add a note saying "multiple ( or 20) spool pieces installed in this section". At the very least when you're doing a HAZOP it will highlight the potential for increased leakage or break / make issues if it is dismantled during some operation, say a well work over.

Thanks again for the info and conversation and feel free to get the half century of responses
LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

You need to remember WHEN a P&ID is generated, and for those that don't know it's at the beginning of the project(or suppose to be). Remember that a P&ID is a SCHMATIC and is NOT used to indicate real-world piping configurations. SO how would anybody generating a P&ID know where to put flanges or unions (other then connection points on "store bought equipment" or generically between two points to indicate a piping spec change) which aid in construction or maintenance of a piping configuration!?? So now your doing an as-built walk-down of a brand new facility, WHY would you note a flange on a header, where for what reason (other then a piping spec change)the welders decided they needed one to aid in piping assemble? You wouldn't see any recognizable configuration to even show where the flange was on a P&ID. Best you could show was it's between two know pieces of equipment, what good would that serve? Adding "extra" stuff to a P&ID is confusing, time consuming, not necessary, and a waste of man power and money. ...And 30 years ago wouldn't be an issue, only now with the know everything computer experts are these "extras" required. ...My $0.02

RE: Do you show flanges on a plant P & ID?

(OP)
11echo,

P & IDs are more commonly produced towards the start of FEED, but then checked, amended and added to over the life of the project, especially as more information becomes available from e.g vendor data, more analysis is undertaken and more data added.

I disagree with your statement " a P&ID is a SCHMATIC and is NOT used to indicate real-world piping configurations". Sure it doesn't show all the elbows, bends, turns etc, but if it shows one take off of a certain size or branch of a different size then a valve then a piece of equipment, that's the order the piping has to follow.

The original question was about showing flanges on valves and then it sort of mutated, but as per my summary in the last post, on the balance of responses and the ease of doing it, showing flanges seems quite reasonable to do.

If a welded decided to add a flange that wasn't shown on a drawing I for one would be very upset...

You're entitled to your opinion and doing it that way - there seems to many others who would do it a different way and that's fine also.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

LittleInch, do you think that all flanges should be shown when they are used to interconnect shop-fabricated, field-erected plant modules to each other?

And I agree that "a P&ID is a SCHMATIC and is NOT used to indicate real-world piping configurations". To me "real-world piping configurations" means just that - what the piping looks like in the field when installed.

"...it shows one take off of a certain size or branch of a different size then a valve then a piece of equipment, that's the order the piping has to follow.". Well of course; I don't think anyone said that wasn't the case.

RE: Do you show flanges on a plant P & ID?

(OP)
Gator,

Yes I do.

Maybe real world piping configuration is being misunderstood here. Clearly it is a schematic, but said schematic can show all relevant parts such as flanges, drains, vents, branches etc etc. It quite often says things like minimum distance, vessel heights and sizes.

Plus this post has now made it to 50 replies ;_)

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Do you show flanges on a plant P & ID?

Hi Everyone,

I do agree with Snorgy 100% on this. I'd like to share few points on this.

1. P&ID is "living" document. It will be revised, added or changed not only throughout of the construction project, but many years after completion of the construction. The plant owner will maintain all systems and equipment, add/remove/upgrade/replace them as time goes by. Obviously, P&ID will be revised and re-issued every time there is change.

2. Having shown all items in P&ID will be handy in those circumstances I have mentioned above. If you working on a maintenance project to replace some plant equipment, knowing flanged connections will help to plan your isolation points accordingly.

I know you may not know everything in the system, and still do your job. Knowing is better then not knowing...

Regards,
Curtis

RE: Do you show flanges on a plant P & ID?

"2. Having shown all items in P&ID will be handy in those circumstances I have mentioned above. If you working on a maintenance project to replace some plant equipment, knowing flanged connections will help to plan your isolation points accordingly."

I agree. But P&IDs are not always kept up to date (the reasons for P&IDs not being up to date can be numerous) and there's no way to be sure of what's there without a site visit. Imagine assuming flanged tie points are there because they exist on the P&ID and then finding out you have to perform hot work.

Perhaps owners' commitments to accurate as-builts has improved over the years.

RE: Do you show flanges on a plant P & ID?

Gator,

I think Owners' commitment to as-builts has gotten progressively worse since I started in 1981. Unfortunately, the expectations of Regulatory bodies in my geographic region(s) has moved in the entirely opposite direction to that trend. The EPCs I subcontract to now all want to START with a good set of Client as-builts, and if they aren't available, they book a trip to the field to create them from the last best known version of the drawings. Invariably, the sites (brown field) are not exactly "as-built", so the P&IDs start off with red right off the top. Then, prior to start-up, after all of the design modifications have been made and the project has been "built", everything is walked down and a new set of "as-builts" is spawned.

Then the Client and others do...other things...that don't get documented, like add control valves, change line sizes, install compressors...and a new EPC contractor comes along and begins to question the competence of the predecessor.

The best you can do is, "When the project started, the site (within scope) looked like this; when the project was over, the site (within scope) looked like that."

The things I do, when it comes to as-builts, I show every flange I see.

RE: Do you show flanges on a plant P & ID?

Hey Snorgy, we started in the business the same year.

I keep hearing great things about laser scanning for as-built piping but have no idea of the cost.



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