P&ID Main Issuance phases (NPSH example)

Hello

In a recent Facebook post, I have talked about an issue where the project team discovered that the pump NPSH needs to be increased, and in order to increase the NPSH, we would need to raise the elevation of the vessel. The post elaborated the effect of this change in the project workflow. You can check out the Facebook post from here if you haven't seen it:

So we see that the severity of a change highly depends on the current project stage. We have gone through different stages of a project in a previous article. I have also create an ebook talking about process design and its role within a project workflow. You can download it from here if you like.

But how is this reflected on a P&ID? Well, in a P&ID, we have different types of issues. Each issue has its own purpose, and based on this purpose, an expected level of detail is considered. Some of the P&ID issuance purposes are:

1. Preliminary / Conceptual issues: Sometimes not even needed as this is a very early project stage. So here, the vessel elevation may not be shown.
2. Approval / review issuance: Used to show the main concepts to the plant owner or client in order to ensure they have the same understanding. Maybe the pump calculations are not settled yet, so in this case, the elevation of the vessel is not shown.
3. FEED issuance: Usually within FEED stage. It has higher accuracy and a higher level of detail but still is preliminary and subject to many changes. So it may show the elevation of the vessel, but still there is a flexibility to change it.
4. Design issuance: Here we are supposed to be in the detailed engineering phase, so things are getting more serious, we shall start procurement activities, 3D model is getting to have high accuracy, so after the issuance of this P&ID the vessel's elevation is expected to be fixed.
5. HAZOP issuance: This issue is considered after evaluation of the design through HAZOP, changes may be late, but if they are necessary, they should be highlighted as soon as possible as being late will cost time due to rework, and maybe even money, if this would affect procured material.
6. Construction issuance: This is supposed to be considered a very late stage, where the project data is settled with vendors, piping isometrics are also settled and shall be considered by construction team, equipment supports and foundations are also settled. Here, changing the vessel's elevation shall cost a lot.

If you like to know more about P&ID preparation, and its operational and safety considerations and common practices, our course is about to launch in the first or second week of July. You can click below to know more about it:

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Have a nice day / night !!

Boostrand