FAMILIARIZATION OF P&ID, HOOK UP DRAWING, JB DRAWING, AND ILD

P&ID: A Piping and Instrumentation Diagram - P&ID, is a schematic illustration of functional relationship of piping, instrumentation and system equipment components P&ID shows all of piping including the physical sequence of branches, reducers, valves, equipment, instrumentation and control interlocks.

A P&ID should include, Instrumentation and designations, Mechanical equipment with names and numbers, All valves and their identifications, Process piping, sizes and identification , Miscellaneous – vents, drains, special fittings, sampling lines, reducers, Permanent start-up and flush lines, Flow directions, Interconnections references, Control inputs and outputs, interlocks, Quality level,  Computer control system input, Vendor and contractor interfaces, Intended physical sequence of the equipment, Instrument root valves, control relays, manual switches, equipment rating or capacity, primary instrument tubing and valves, pressure, temperature and flow data, elbow, tees and similar standard fittings, extensive explanatory notes

Hook up drawing: Hook-up drawing is a detailed drawing showing typical installation of instrument in a correct manner so that instrument operates properly. Hook-up drawing indicates tubing slopes, position of instrument in reference to process tapping point, scope break between instrument v/s piping. Hook-up drawing also gives information about the requirement of bulk material for each installation. It also details its specification (size, type and material) and the quantity.

JB drawing :

Junction box is an intermediate between instrument and control panel. Junction box is an electrical box which contains terminal blocks. The cables from the instruments come to one side of the terminal block and from the other end it goes to the control panel. JB drawing shows instrument  and its terminal numbers which are to be connected, instrument cable number, junction box number, terminal number assigned for the specified instrument,multi-pair cable and  pair number , marshaling cabinet number, terminal number in marshaling cabinet.

ILD: Instrument Loop diagram represents detailed drawing showing a connection from one point to control system. It could be connection between: Field instrument to control system (or vice versa), Signal from Control Panel to control system (or vice versa),Signal from MCC to control system (or vice versa),Signal from one control system to another system.

                  Loop diagram shows instrument (in a symbol) and its terminal numbers which are to be connected, instrument cable number, junction box number, terminal number assigned for the specified instrument, multi-pair cable and  pair number , marshaling cabinet number, terminal number in marshaling cabinet, control system details (rack, slot, I/O channel). It also clearly indicates location of each equipment by means of border line. A limit Loop Diagram usually shows a single control loop which means it could only contain just one input (sensor to control system), just one output (control system to final element) or combination of both.