Never miss anything while review P&ID-Check list for an Instrument Engineer

P&ID Instrumentation Review Checklist

A comprehensive guide for Instrument Engineers in the Oil & Gas Industry.

1. General & Document Control

Is the P&ID number and title correct as per the document list?

Is the revision number and date consistent with the project stage?

Are all relevant legends (general, symbols, abbreviations) referenced or included?

Are battery limits clearly defined and consistent with other P&IDs?

Is the equipment numbering and naming consistent with the equipment list?

Are line numbers unique and do they follow the project's line numbering philosophy?

Is the flow direction indicated correctly on all process and utility lines?

Are all continuation notes to and from other P&IDs clear and correct?

Is there a 'cloud' around all changes from the previous revision?

Are notes and callouts clear, unambiguous, and not conflicting with symbols?

2. Instrument Identification & Tagging

Does instrument tagging follow the ISA-5.1 standard and project specifications?

Are instrument bubbles correctly shown (e.g., field-mounted, DCS, SIS)?

Is the loop numbering unique and logical within the unit/area?

Is the functional identifier (e.g., F for Flow, T for Temp) correct for the measured variable?

Are suffixes (e.g., A, B for redundant instruments) used correctly?

Are instruments part of a packaged system (e.g., compressor, dehydrator) clearly identified with a package tag?

3. Flow Instruments (FT, FE, FG, FCV)

Is the flow element (FE) type specified and appropriate for the service (e.g., Orifice, Coriolis, Ultrasonic)?

Are upstream/downstream straight-run requirements for orifice meters considered (check for nearby valves/bends)?

Are block and bypass valves shown for maintenance of in-line instruments like Coriolis or ultrasonic meters?

For orifice plates, are pressure taps correctly oriented (side for liquid, top for gas)?

Are flow control valves (FCV) shown with correct fail-safe position (Fail Open/Fail Close/Fail Last)?

Is a bypass line shown around the flow control valve?

Are handwheels for manual operation of FCVs shown where required?

Is the flow transmitter (FT) correctly linked to the flow element (FE)?

Are local flow indicators (FG) shown where needed for operator convenience?

4. Level Instruments (LT, LG, LSH, LSL)

Is the level transmitter (LT) technology appropriate (e.g., DP, Radar, Ultrasonic)?

Are nozzles for level instruments located correctly on the vessel (avoiding inlets, vortex breakers)?

Is the range of the level transmitter (e.g., LSHH, LSH, LSL, LSLL) clearly indicated on the vessel sketch?

Are bridles or stilling wells shown for external level transmitters or guided-wave radar?

Are root valves (block valves) shown for all instrument connections to the vessel?

Is a local level gauge (LG) provided for visual indication alongside the transmitter?

Does the level gauge range cover the full range of the level transmitter and switches?

Are vent and drain valves shown on level bridles and level gauge connections?

Are level switches (LSH, LSL) shown as separate instruments or integral to the transmitter?

For DP transmitters in closed tanks, is the low-pressure side correctly connected to the vessel's vapor space?

5. Pressure Instruments (PT, PG, PSH, PSL)

Is the pressure instrument connection point logical for what it needs to measure (e.g., pump suction/discharge, vessel top)?

Is a block-and-bleed valve configuration shown for each pressure instrument?

Are local pressure gauges (PG) provided at key locations (e.g., pump suction/discharge, filters)?

For differential pressure transmitters (PDT), are both high and low-pressure taps shown correctly?

Are diaphragm seals or chemical seals specified for corrosive, viscous, or high-temperature services?

Is a siphon or pigtail shown for steam service to protect the instrument?

Are pressure switches (PSH, PSL) correctly identified for their safety or control function?

Is the pressure control valve (PCV) fail-safe position correct (e.g., fail open for depressurizing)?

6. Temperature Instruments (TT, TE, TG, TW)

Is a thermowell (TW) shown for every temperature element (TE)?

Is the temperature element located to measure a representative process temperature?

Is the thermowell insertion length appropriate for the pipe size (typically 1/3 to 1/2 of pipe ID)?

Is the temperature element type specified (e.g., RTD, TC) if known?

Is a temperature transmitter (TT) shown, or is the signal direct to the control system?

Are local temperature gauges (TG) provided where required?

For skin-point temperature measurement on furnaces/heaters, is the symbol correct?

Is the temperature control valve (TCV) fail-safe position correct for the application (e.g., fail close on a heating medium)?

7. Control Valves (FCV, LCV, PCV, TCV)

Is the valve type symbol correct (e.g., globe, ball, butterfly)?

Is the actuator type shown (e.g., Diaphragm, Piston)?

Is the fail-safe position (FC/FO/FL) clearly indicated for every actuated valve?

Are block valves (upstream and downstream) and a bypass line shown for all control valves in critical service?

Is the bypass valve correctly sized (typically smaller than the main line)?

Is a drain/vent shown between the block valves for maintenance?

Is an I/P converter (current-to-pneumatic) shown for pneumatic actuators?

Is a positioner (FY) shown for the control valve?

Are limit switches for open/closed position feedback (ZSC/ZSO) shown where required?

Is a volume tank/booster shown for large or fast-acting actuators?

Is the instrument air supply line shown with a filter/regulator?

Are solenoid valves (SOV/XY) shown for tripping/interlock functions?

8. On/Off & Emergency Shutdown Valves (XV, ESDV, BDV)

Are shutdown valves (ESDV/SDV) and blowdown valves (BDV) tagged correctly as per safety requirements?

Is the fail-safe position clearly indicated and appropriate for the safety function?

Are open/closed feedback switches (ZSC/ZSO) shown for all ESD/BDV valves?

Is the actuator type shown (e.g., pneumatic spring-return)?

Is the controlling system specified (e.g., SIS/ESD system)?

Is the solenoid valve (XY) shown and connected to the correct system (SIS)?

Is fire-proofing specified for ESDV actuators where required by philosophy?

Is car-sealing/locking for manual block valves around ESDVs shown (e.g., Car Seal Open)?

9. Analyzers (AT, AE)

Is the analyzer type specified (e.g., pH, O2, H2S, Gas Chromatograph)?

Is the sample take-off point correctly located to get a representative sample?

Is a sample conditioning system shown or noted?

Is the sample return line shown, and does it return to a suitable, lower-pressure point?

Are double block and bleed valves shown for sample point isolation?

10. Control Systems, Signals & Interlocks

Are signal lines correctly represented (e.g., electric, pneumatic, data link)?

Are instruments correctly assigned to the DCS (Basic Process Control System) or SIS (Safety Instrumented System)?

Are interlock numbers (I-XXX) shown and are they unique?

Is the interlock logic clearly depicted or referenced to a logic diagram?

Is there a clear distinction between DCS control loops and SIS safety functions?

Are soft-links or data links between systems (e.g., DCS to package PLC) shown correctly?

Are hardwired signals for critical shutdowns correctly shown?

Are alarms (e.g., PAH, LAL) associated with the correct instrument and system?

Is the instrument air header shown with connections to pneumatic instruments/valves?

Are computer functions (e.g., calculation blocks) shown with the correct symbol?

Is redundancy shown correctly (e.g., 2-out-of-3 voting for SIS transmitters)?

11. Installation & Miscellaneous

Are instrument hook-up drawings referenced?

Are requirements for heat tracing or insulation on instrument lines/bodies shown?

Are pressure safety valves (PSV) shown with block valves upstream/downstream where permitted?

Is the PSV discharge routed to the correct flare/vent system?

Is a rupture disc (PSE) shown upstream of a PSV in fouling service?

Is a pressure instrument shown between the rupture disc and PSV to detect leakage?

Are corrosion coupons or probes shown where specified?

Are vents and drains on equipment and piping correctly shown and sized?

Are spectacle blinds, spades, and spacers shown for equipment isolation?

Is the "Normal Operating Position" of manual valves indicated (e.g., NO, NC)?

Are locked open/locked closed (LO/LC) requirements for manual valves shown?

Is there adequate access shown for maintenance and operation of instruments and valves?

Are all vendor package interfaces clearly marked and documented?

Are all instrument connections on the P&ID reflected in the vessel/piping drawings?

Tagged Engineering Deliverable Check List