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Instrument Piping and Tubing QAQC Questionnaires

 Instrument Piping and Tubing QAQC Questionnaires

Tubing Installation


PIP Interconnecting instrument piping (tubing) between the primary metering

element and the measuring instrument shall be 0.5 inch AISI Series 300 stainless

steel tubing minimum. Tubing wall thickness shall be 0.89 mm (0.035 inch)

minimum. Applicable piping code and process requirements shall prevail.

PIP Interconnecting piping shall be limited to a maximum length of 6 m (20 ft) for

meters in control loops. Interconnecting impulse tubing between a differential

flow element and a transmitter in compressor suction service shall be kept as

close as possible or close coupled.

PIP Interconnecting Seal liquid to protect flow meter impulse tubing and secondary

measurement instrumentation from corrosive fluids or to provide a stable

hydraulic measuring medium shall be free flowing but not volatile under normal

process and external ambient conditions. Seal liquids shall not be miscible with

nor react with the process fluid being measured. Seal liquids shall be selected so

that their potential for contamination of the process fluid is acceptable.

PIP (Addition) PIP PCIDP000 “Differential Pressure Installation Details” shall be used

for interconnecting the flow Differential Pressure Instruments to the root valves

of the differential producers.

PIP 4.6.2.c (Addition) Purging of impulse lines shall be considered only if other methods

have failed to eliminate problems of condensation, vaporization, corrosion or




8.1.1 Pressure and D/P instruments in liquid or condensable vapor service shall be selfventing

(i.e., mounted below the process connections) with all impulse lines

sloping downward approximately 1:10 minimum toward the instrument.

Pressure and D/P instruments in gas service shall be self‐draining (i.e., mounted

above the process connections) with all lines sloping downward approximately

1:10 minimum toward the process connection.

8.3 Instrument Piping and Tubing

The instrument piping and tubing installation shall ensure the reliable and

accurate operation of the instrument(s) involved, and allow sufficient access for

maintenance, calibration and testing. It shall be possible to test all alarm and

shutdown initiating devices, without interfering with the process operation of

the packaged unit.

Instrument tubing shall be adequately supported to eliminate any vibration

transmission to the instruments or excessive load to the piping connection,

process line or vessel.

Tubing to and from non‐indicating instruments shall have a plugged tee or

equivalent test point for calibration and testing purposes.

All threaded connections shall be tapered per ASME B1.20.1.

All incoming and outgoing interconnection lines shall terminate in bulkhead

fittings. The lines shall be marked with the tag numbers of the corresponding

instruments. Bulkhead fittings shall be installed with adequate spacing to ensure

that any connection can be removed without the need to remove other fittings.

9.2.2 Tubing and Fittings Tubing Stainless steel tubing shall be seamless, annealed, minimum

wall thickness 1.24 mm, per ASTM A269, Grade TP‐316L.

Instrument air tubing shall be ¼ inch, 3/8 inch, or ½ inch OD

stainless steel. Wall thickness shall be 0.75 mm or larger. Fittings 316 stainless steel compression fittings shall be either Crawford

Swagelok, Parker Hannifin A‐Lok, Parker Hannifin Corp. CPI or

Hoke Gyrolock. Any proposal to use fittings other than those

listed above shall be reviewed by Supervisor, Instrumentation

Unit, Process Instrumentation Division, and P&CSD.

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