Demolition PIDs and drafting workflow on brownfield projects

[Vinu1991]

Hi All,

I was preparing a PID markup the other day on my project and the markup was for the updation of a demolition PID. I have some doubts over usage of the term demolition in the context of a PID.

On some projects, I have seen that if any part of an existing facility is being deleted then we prepare a demolition PID. On other projects, they say that if you are making any changes and not necessarily only removing an existing component completely, you still need to capture it in the demolition PID. In all cases the as-built drawing is the reference drawing.

So, my question is as follows. Are demolition PIDs made only when you are removing an existing part of a facility completely or when you are making some changes/modification to an existing facility (e.g. cutting a spool piece but not necessarily removing it to make way to add some flanges), or are both kind of changes to be captured in a demolition PID?

Also please give me some inputs as to what the general practice (engineering drafting workflow) is in relation to the updation of a PID during a brownfield project.

Currently, my understanding on the engineering drafting workflow on a brownfield project is as follows:

1. Catch hold of the as-built PID.
2. Markup on the as-built PID for the preparation of the demolition PID.
3. Use the drafted demolition PID as a guide/input to prepare the construction PID.

Any inputs on clarifying the above would be very helpful.

Thanks and Regards,
Vinayak

 

[Terrifyingtesttube]

I work in food & beverage for a process design and engineering consulting company, and the way that we typically do it is:

Current drawings from client, verify as needed
If there is substantial removal work then the lines, equipment, and instruments to be removed are highlighted (usually bold/black against grey). Identify all the interfaces between demo and keep with tie-points. These are the demolition drawings.
Remove the "demolished" items from the drawings, adding in the new stuff (again highlighted in bold/black). These are the installation drawings.
Once the work is complete go through for as built with the installation drawings, mark them up as needed, and issue final works drawings.

If it is a simple tie-in like just adding a tee-piece for a new water supply, then we usually just do an installation drawing.

If it is a simple change like changing a weld to flange connection, then depending on the client I could see some asking for both demo and install, and some being okay with just a single drawing with an explanatory note.

 

[MortenA]

Its client (perhaps even project) specific. Some uses demolition P&IDs some dont. They are in my experience only for marking up stuff that will be removed (this may include stuff that is the replaced). I wouldnt caputre holds and notes that becomes redundant. That would be in the new revision of the P&ID. I wouldnt consider the demol. P&ID a seperate revision of the P/`&ID but rather a project drawing preferrably with it own doc no. based on the original doc no. So it seems like i have the same understanding as you do.

 

[don1980]

Two sets of marked-up P&IDs (Project P&IDs and Demo P&IDs) are generated for all projects that involve modifications to existing plants. The Demo P&IDs simply show what is being deleted from the operating process. They identify the equipment and piping that will no longer be part of the plant process. Demo P&IDs don't necessarily mean that all the "dead" equipment and piping will physically removed - they just mean that this stuff is no longer part of the process. In some cases, all the dead piping and equipment is removed at the time the new stuff is being installed. In other cases, the plant may decide to just leave it there (or some of it there), and wait until they accumulate enough dead piping and equipment to justify a project to go remove all this stuff.

It's essential to have up-to-date P&IDs that show all the piping and equipment that part of the operating plant. So, as part of every new project, it's essential to identify all the stuff that will no longer be part of the new process - no longer appear on the plant P&IDs - once the project is completed and installed. But, the piping and equipment within the "demo scope" (shown on the demo P&IDs) may or may not be physically removed at the time this new project is constructed. The extent to which the dead piping and equipment is physically removed is simply one of the many decisions that each project team must decide - they can physically remove it now or wait till later. Regardless, this stuff will no longer show up on the operating plant's P&IDs.

 

[MortenA]

So you agree with OP?

 

[tickle]

I am not sure that a set of rules can be put down that will satisfy each and every project. At the end of the day, the benefit of producing a demolition P&ID should be considered against the benefit that it adds. A demolition P&ID for the installation of flanges adds little value, but a demolition P&ID may add lots of value for a complicated project. It may be that several demolition P&IDs are required if the demolition is to be done in stages, as well as intermediate operating configurations.

My preference is to ensure that each stage of the project has a different revision of the P&ID (rev 1, Rev 2 rev 3 etc). Some companies create a new drawing to capture demolition typically XX-YY-111D, but it depends on document management systems. Further each individual P&ID may require revision (updation) during the project.