Page 33 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

18 Applied Process Design for Chemical and Petrochemical Plants

Materials of Construction for Lines

The process designer must also consider the corrosive
nature of the fluids involved when selecting construction
materials for the various process and utility service lines.
Some designers attach these materials designations to the
line designation on the flowsheets, while others identify
them on the Line Summary Table (Figure 1-240). Some
typical pipe materials designations are:

CS40 - Carbon steel, Sch. 40
CS80 -Carbon steel, Sch. 80
SS316/10 -Stainless steel
316m Sch. 10
GL/BE - Glass bevel ends
N40 - Nickel, Sch. 40
TL/CS - Teflon-lined carbon
steel
Figure 1-18A. Computer generated P. and I D. flowsheet. Courtesy
of Intergraph Corp., Bui. DP016AO. PVC/CS Polyvinyl chloride - lined CS
PP - Solid polypropylene
(designate weight sch)

Test Pressure for Lines
The process designer also needs to designate the
hydraulic test pressures for each line. This testing is per-
formed after construction is essentially complete and
often is conducted by testing sections of pipe systems,
blanking off parts of the pipe or equipment, if necessary.
Extreme care must be taken to avoid over pressuring any
portion of pipe not suitable for a specific pressure, as well
as extending test pressure through equipment not
designed for that level. Vacuum systems must always be
designed for "full vacuum," regardless of the actual inter-
nal process absolute vacuum expected. This absolute zero
design basis will prevent the collapse of pipe and equip-
ment should internal conditions vary. Some line design
systems include the test pressure in the line code, but this
Figure 1-188. Computer generated instrumentation detail for P. and often becomes too unwieldly for drafting purposes.
I D. flowsheet. Courtesy of lntegraph Corp., Bui. DP016AO. The usual complete line designation contains the fol-
lowing: (1) line size (nominal); (2) material code; (3)
sequence number; and ( 4) materials of construction.
G-Glycol Examples: 2"-CL6-CS40
SA- Sulfuric Acid 3"-CL6a-CS40
B-Brine 4"-RW1-CS40
CL - Chlorine 16"-Sl 50-CS40
P - Process mixture ( use for in-process lines not 3"-P-TL/CS
definitely designated by other symbols) See Figures 1-23 and l-24A through D.
Some engineers rearrange the sequence of the code
although the information remains essentially the same.
The line number sequence is conveniently arranged to
Sometimes it is convenient to prefix these symbols by L start with one (1) or 100 for each of the fluid designations
to indicate that the designation is for a line and not a ves- (CL, P, etc.). Since the sequence numbers are for coordi-
sel or instrument. (text continued or, page 23)