Petroleum Refining Design and Applications Handbook. A. Kayode Coker

should internal conditions vary. Some line design systems include the test pressure in the line code, but this often becomes too unwieldy for drafting purposes.

The usual complete line designation contains the following: (1) line size (nominal); (2) material code; (3) sequence number; and (4) materials of construction (see and Figures 14.18 and 14.20a–d).

Examples:	2″-CL6-CS40
	3″-CL6a-CS40
	4″-RW1-CS40
	16″-S150-CS40
	3″-P-TL/CS

Some engineers rearrange the sequence of the code although the information remains essentially the same. The line number sequence is conveniently arranged to start with one (1) or 100 for each of the fluid designations (CL, P, etc.). Since the sequence numbers are for coordination purposes and will appear on piping drawings, Line Schedule (Figure 14.20a through d), the number has no significance in itself. It is convenient to start numbering with the first process flow sheet and carry on sequentially to each succeeding sheet. Sometimes, however, this is not possible when several detailers are preparing different sheets, so each sheet can be given arbitrary beginning numbers such as 100, 300, 1000, etc. Although the sequential number may be changed as the line connects from equipment to equipment, it is often convenient to use the system concept and apply alphabetical suffixes to the sequence number as shown in Figures 14.18 and 14.19. This contributes materially to the readability of the flowsheets. Each line on the flowsheet must represent an actual section or run of piping in the final plant and on the piping drawings.

Figure 14.18 Examples of line numbering.

Figure 14.19 Use of alphabetic suffixes with line symbols.

Figure 14.20a Line schedule.

      Figure 14.20b Pipe line list.

      Figure 14.20c Line schedule sheet.

Figure 14.20d Line summary table.

      Suggested guides for line identification for any one principal fluid composition:

      1 1. Main headers should keep one sequence number (Figure 14.18).

      2 2. New sequence numbers should be assigned:(a) Upon entering and leaving an item of equipment.(b) To take-off or branch lines from main headers.(c) To structural material composition of line changes.

      3 3. Alphabetical suffixes should be used in the following situations as long as clarity of requirements is clear, otherwise add new sequence numbers.(a) For secondary branches from headers or header branches.(b) For by-pass lines around equipment, control valves, etc. Keep same sequence number as the inlet or upstream line (Figure 14.18).(c) For identical multiple systems, piping corresponding identical service items, and lines.

      In order to coordinate the process flowsheet requirements with the mechanical piping specifications, Line Schedules are prepared as shown in Figures 14.20a through d. The complete pipe system specifications are summarized by codes on these schedules.

Equipment code designations can be developed to suit the particular process, or as is customary a master coding can be established and followed for all projects. A suggested designation list (not all inclusive for all processes) for the usual process plant equipment is given in Table 14.4 and process functions in Table 14.5. The various items are usually numbered by type and in process flow order as set forth on the flowsheets. For example:

Table 14.4 A system of equipment designations.

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AD	- Air Drier
AF	- Air Filter
Ag	- Agitator
B	- Blower
BR	- Barometric Refrigeration Unit
C	- Compressor
CP	- Car Puller
CT	- Cooling Tower
CV	- Conveyor
D	- Drum or tank
DS	- Desuperheater
E	- Heat Exchanger, condenser, reboiler, etc.
Ej	- Jet Ejector
Ex	- Expansion Joint
F	- Fan
FA	- Flame Arrestor
Fi	- Filter (line type, tank, centrifugal)