Friday, September 17, 2010


In the P&ID , It is not only show the pipe, valve, fitting, flange but its show the istrument equipment that to provide to control the system operation. Like in the our body, the istrumentation is syaraf or brain and it function for feeling the activities in our body.

Here refer on the read from the book of the piping design, you will see the , what is the instruments equipment and shall be shown in 100% in the piping drawings such piping layout, piping section and piping isometric but in Bill of materials , the piper can not put the instrument materials in his Bill Of Materials, because usually the instrument materials is prepare in  Bill of Materials Isntrument.


-  Size of connection ( 1", 1 1/2", or clamp/skin)
-  Type of connection (female threaded, flanged, welded, or skin)
-  The weight of the connection is correct (threaded is 6000#, flanged (including weldolet) is sch
-  The pipe is at least the minimum size specified for a temperature connection (Fluor Standard is

    3" on buttwelded pipe, 2" @ threaded & socketwelded tees)
-  A temperature connection on an elbow is located with the thermowell "into" the flow
-  There is 2'-0" clear from the end of the olet or face of flange (for instrument installation/removal)
    to the next obstruction
- The instrument (thermometer or thermocouple) does not interfere with walkways/aisleways
- If the thermowells are squad checked, they aren't too long for the pipe OR the equipment (in the
   downpour area of a vertical vessel) - they should terminate near the center of the pipe and will
   not interfere with equipment internals
- Whether readable or blind - the instrument is accessible per the project Piping Layout
- When the instrument is readable - it can be read
- The piping components on the parts list on a trim iso for a flanged temperature connection
   includes bolting and gaskets
- The reductions on a "pup piece" follow the instrument design Standard - not the Piping Material
   Specification (if the contest is swage vs reducer)
- The instrument is in the correct location when specified as either VAPOR or LIQUID on the
   P&ID at a vertical trayed vessel
- The instrument is located per the P&ID


Gauges, switches, alarms, differential pressure (d/P cells)
- The stopping point of Piping's responsibility and the beginning of instrument design's
   responsibility (after the valve)
- The size of the connection (1/2",3/4", 1", 1 1/2")
- The connection is the correct number of pipe diameters from the control valve when the control
   valve is a back-pressure regulator or a pressure reducing regulator (BPR or PRR)
- The instrument is accessible per the project Piping Layout Specifications
- The instrument is located per the P&ID
- The instrument is located so as to permit the installation of the portion downstream of Piping's
   responsibility and not interfere with walkways/aisleways - refer to 000 250 2720

Relief valves

- The outlet is larger than the inlet (in most cases)
- The rating of the inlet flange is higher than the rating of the outlet flange (in most cases)
- Bolts longer than the standard bolt length are in the parts list on the piping isometric
- Downstream piping is not pocketed
- Tailpipes discharging vertically upwardhave a weep hole
- Inlet & outlet piping has been to stress analysis
- Inlet & outlet piping has been reviewed for hydraulics if the relief valve is not "minimum" to the
   system it is protecting
- Except on thermal relief valves, springs are always oriented vertically upward
- The relief valve has been correctly modeled in PDS
- If the downstream block valve is in a horizontal run, the hand wheel is in the horizontal to
   vertically down position


- The gauge glass can be seen from the case of the level controller (didplacement-type)
- The case mounting and orientation of the "arm" of the level controller (displacement-type)
   has been set by piping
- The swing of the case door(displacement-type controller) is not blocked
- All valves (block & vent & drain) are operable
- The level gauge glass can be cleaned

Meter Runs
- The size matches the P&ID
- If the beta ratio is ANYTHING other than .75 (000 250 2710), and the upstream and
   downstream runs used on the project are per the Fluor chart, this will be brought to the
   attention of the piping supervisor, who, in turn, will bring it to the attention of control systems,
- The upstream and downstream runs have no welds within them

Coriolis Meters
- Motion isolation supports are properly located per the manufacturer's recommendations

Control Valves

- The flow pattern matches the flow pattern on the P&ID (angle vs straight)
- The size matches the P&ID
- If there is a handjack, it has been oriented by Piping
- The actuator type matches the type shown on the P&ID
- The size, rating and facing on the iso matches the instrument outline
- The end-to-end dimension on the iso matches the instrument outline
- The actuator model number is specified before the iso is checked
- The actuator modeled is the one specified

After you read the instrument materials/equipment, we can know much better about the piping design configuration between piping and instrument.
As you know, many companies in the world used Instrument Engineer and Piping Engineer to Update the PFD (Process Flow Diagram) to became a P&ID (Process and Instrument Diagram )

So the Piping Engineer should know the P&ID much better because if the piping engineer do not know about the P&ID is like a bird without two wings

Rumbai, 17 September 2010.

Sources : me and friend in Flour Daniel.

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