The hook up drawing is a deliverable document that showing the sequence of parts with technical considerations for specific installation of field instruments. For example when installing DP Transmitter, the pressure tapping shall be taken on side or top of pipe with consideration of the fluid on the flow line. Describe scope limit between instrument discipline and other (piping or mechanical). The tube of pressure sampling shall be slope to prevent any fluid trap and so on. The drawing is a guidance in correct way up of installation so that field instruments will operate correctly as expected for accurate sensing and best practice.
There is one important thing in the instrument hook up drawing that engineers have to carefully prepare, that is material take off (MTO). MTO consist of detail required parts to be hooked up.
To create an instrument hook up drawing, we need other document to be as refference, those are P&ID and instrument datas heets.
The purpose of instrument hook up itself is to be as guidance what spareparts shall be prepared and hook up guidance during installation.