Flow lines should be labeled to show pipe size, line service identification, line number, line material, piping class and the line pressure rating.
Numbering Process
Most companies have their own method of numbering lines. Typically, a line number will be assigned to a primary flow line and then incremented as it branches. If there is no in house process to number the lines, start at the upper left line (on the P&ID) and use that as the lowest number. Assign numbers up to each piece of equipment. Do this for all lines. Next start with the outlet lines. Once all the primary lines are numbered, secondary lines should be numbered with the same methodology.
Line Numbering Example
A typical line number or line designation would be as follows:
3" PV-500-040-A-2"HC-ST
Where:
3 = Nominial diameter of the line
PV = Service Classification
500 = Line Number
040 = Pipe Schedule
A = ANSI Pressure Rating
2"HC = Coating or Insulation thickness and function. This example shows 2" insulation for the purpose of heat conservation. Other examples might be CC for cold conservation, FP for fire protection or PS for personnel safety.
Some coatings might be C for cement lined pipe, F for fiberglass, G for galvanized, P for plastic.
This is an optional item and is typically left off if there are no entries on it.
ST = Type of heat tracing to be used. This example shows steam tracing as the type of heat tracing. Other examples might be ET for electrical tracing.
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