If you do mean the Line Number then you would need to justify the cost of putting the Line Number on each line.
The cost would require; a serious study of where to put the number; how many times the number would be required on each line; the method of application; the validation of the correctness of each number-to-line; and the long term maintenance of the numbers.
Sometimes its possible to do all the right things and still get bad results
As long as valves and equipment are properly tagged, I don't personally see much need for identifying line numbers on piping. There may be cases where it is justified, but in my experience, it's not something that's commonly done.
Disagree respectfully.
As some cost of adding the line ID on the pipes, it can be useful for the safety O&M activities and any future engineering work, especially for a complicate unit with multiple process piping. Many safety incidents occurred as the wrong pipes were marked for the maintenance work.
You can order the pipe ID labels and wrap or stick it on the pipes.
Will the facility ever be modified or upgraded? If yes, can it be certain that operations will update the line tags?
In any case, lines should be walked down from source to destination to confirm that real world matches the documentation prior to any work being started.
Yes, it can be a pain/difficult to do this but failure to do this can cause large problems down the road.
If you have to reply on correct labelling of lines for safety then you may want rethink how the system is designed. Safety should not rely on the operators checking line numbers. Consider valve interlocks etc.
From a construction point of view it might be nice, but usually this is the isometric number.
Can't say I've even seen this in practice and dubious about it's benefit, if any, on process safety.
Making sure each valve and instrument is correctly tagged is an ongoing issue in many plants - Tags get lost, damaged, valves and instruments replaced or moved, but never re-tagged. This is far more important than the line number.
Why do you ask?
what's your view?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I wouldn't ever bother with putting line/tag numbers on pipe runs. Use ANSI A13.1 for pipe marking and hang tags on components as others have suggested.
Pipe marking labels must effectively communicate the contents of the pipes and give additional detail if special hazards (such as extreme temperatures or pressures) exist. The legend should be short in length and easy to understand. For example, the legend "Steam 100 PSIG" specifies the contents as well as the additional pressure hazard. An arrow should be used in conjunction with the legend to show which direction the material flows. If flow can be in both directions, arrows in both directions should be displayed.
ASME A13.1 was updated in 2007 and reaffirmed in 2013. It uses a color code chart with six standard color combinations and four user-defined combinations as shown below. The colors are based on the contents of the pipe and in general, the most hazardous feature of the contents is used to determine the colors used.
Have never seen process plants with labeling consisting of P&ID numbers.
Different plants at different geographical locations use line numbers painted / stencilled on piping (both insulated and bare) at frequent intervals. Some are easy to understand, others are quite complicated. Also there is a colour coding for each piping. Normally different oil and gas industries have their own piping colour coding and numbering guidelines.
As an inspection and corrosion personnel, I have found these markings extremely helpful, even if they are complicated. You get used to them with time.
From a process safety perspective, as soon as one comes down to the plant from his comfortable office, the piping markings become the guiding star or the modern day GPS.
I am with Bimr on this. ASME A13.1 compliant pipe marking labels should be enough with commodity (e.g. "150 psi Steam", or "30 psi Natural Gas", etc.) and colour coding per ASME A13.1. No need to invent bicycle here, and use what already exists.
Line numbers will be overkill on top of system commodity with colour coding. From operational and maintenance prospective, no need to complicate things.
