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Proper procedures to install instrument and air process piping/tubing

asked Oct 6, 2015 in Engineering by jakangaru (2,010 points)
Sharing the installation procedures on instrument and air tubing/piping.

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answered Oct 6, 2015 by jakangaru (2,010 points)

Air:

  • Air piping/tubing should adhere to project specific piping specification. Distribution to each instrument should be via a ¼ turn isolation valve.
  • The hook-up from the air distribution manifold, to the instrument and process piping, should be installed with sufficient flexibility, to allow for normal equipment movement and to isolate against vibration.
  • Tubing runs, multiple or single tube, should be supported at distances of 24 inch, using stuff blocks or equal.
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answered Oct 6, 2015 by jakangaru (2,010 points)

Instrument:

  • Instrument process tubing/piping should not be fastened to plant process lines. Expansion bends should be provided where process lines could transmit vibrations to the instrument.
  • Impulse tubing should have a slope of minimum 1:10 with no pockets.
  • Each instrument should be available for maintenance and disconnection without interfering with the process.
  • Transmitters in gas / vapor service should be installed such that their impulse lines slope back to the process tapping point (self-draining) without any pockets. For liquid service, transmitters should be located to avoid high points.
  • Tubing clamps should be made of non-corrosive material, 316 SS or flame retardant plastic.
  • Galvanic corrosion between tubing and tubing support system should be avoided. The tubing clamp should, when installed, not allow for water/seawater to be accumulated between tubing and tubing clamp.
  • Parallel run of tubes on the same tray/support should be arranged such that it is possible to have access to every connection point.
  • Installation into, or through, panels should be made via bulkhead unions.
  • Instrument tubing and cable maybe installed on the same field tray for shorter distances (maximum 16 feet). Instrument tubing and cables may be routed through the same penetration/transit, provided the transit is approved for such use.
  • All tube cutting should be performed with a proper tube cutter. Hacksaw should not be used.
  • All tubing for hydraulic systems should be hot oil flushed before taken into service.
  • For all NPT threads, Loctite 577 or similar should be applied. Teflon tape should not be used.
  • When multiple tubes are run in parallel they should be run in the vertical plane.
  • Where tubing is used, the supplier’s installation procedure and tools should be followed. Unsupported tubing at the instrument should not exceed 12 inches. Where possible, impulse lines of instruments adjacent to each other should be laid on tray. Tubes on racks should be supported with tubing clamps every 40 inches. Tube clamps should be fixed to the tray by means of bolts and nuts. Clamps, bolts and nuts should be 316 SS.
  • Long tubing runs should be avoided, where possible, to reduce the number of fittings and the possibility of leaks.
  • Piping, tubing and fittings installed, but not connected, should have the end sealed, either temporarily for short period or using pipe caps/plugs for long period.
  • All instrument impulse lines should be de-burred and thoroughly blown through with clean dry air before connecting to instruments.
  • Support racks for multiple tubes may be run in the vertical or horizontal plane. When runs are horizontal and there is a possibility of oil or dirt falling on the racks, then a protecting cover should be installed.
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