Points of emission on P&IDs 4

[MikalT]

Is it a standard practice to show all possible points of emission (threaded connections like vents and drains or break flanges) on Piping and Instrument Diagrams? Is this only for hazardous fluids/gases? Has OSHA dictated that these be shown? Thanks for any insight!

 

[TD2K]

I've not seen this requirement though I've not dealt with highly hazardous substances. To my thinking, putting it on the P&ID would not provide any protection to the workers or people potentially exposed to the material. That's more a function of the piping specification and piping practice (flanged versus threaded, minimizing flanges, etc).

All valves should be shown IMO to accurately depict the system. Flanges are not typically shown except at vessel connectons (and then not always) and/or where you have a spectacle blind in the system or something like that. Basically, flanges shown are the exception.

 

[saxon]

MikalT, I've seen it done after the fact on "Asbuilt Dwgs." coming back in from the field. Due to the nature of the P&ID (it has no HI points or LO points, in most cases)they only show general location in relation to the piping specialties on the line. These types of marks are dependant on the requirements or desire of the company or chief engineer in charge.

Hope this helps.
saxon

 

[MikeClay]

I have also seen this done to identify and document all points for fugitive emissions. As "piping components", they were tagged and tracked in the maintenance system. This information was used to schedule and document routine inspections.

--Mike--

 

[Guidoo]

As shown by other posts, it may be done sometimes but: No it is not standard practice to show all emission points on the P&ID. Flanges, high point vents and low point drains are normally not shown.
However, different companies have different P&ID standards...

 

[moltenmetal]

There IS NO STANDARD for P&IDs- it varies from company to company and plant to plant. We see customers who try to treat P&IDs like piping drawings, identifying all sorts of connection types and locations, while we see others who don't even show all the VALVES that can give the operator access to the process fluid (i.e. the delete drains, vents and flush/bleed ports on transmitters etc.).

I personally believe that a P&ID should show every valve that gives the operator access to the process, but should not attempt to be a piping drawing. If you must keep track of every connection and joint which might become a point of emission in a piping system, your only recourse is to keep a set of accurate as-built pipe routing and isometric drawings. A 2-D P&ID cannot do a decent job of representing that information anyway, without losing its ability to fulfill its core functions.

 

[BenThayer]

Our site does something similar to what you are referring to. We tag and identify fugitive emissions monitoring points on our P&I-D's. These are basically valves that have packing but does not include gaskets, threaded connections, etc.

This is our method to comply with EPA requirements. The valves are tagged in the field with a unique number and that tag number is also on the P&I-D. This makes it more convenient to locate the actual valve in the field.

ben