Page 438 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

404 Applied Process Design for Chemical and Petrochemical Plants

Figure 7-3a cont.

MATERIAL
ITEM PART NAME
81C,83C 81S,83S
1 BODY CARBON STEEL 316 S.S.
2 DRIVE PIN 316 S.S. 316 S.S.
3 SPRING WASHER CARBON STEEL 316 S.S.
4 SPRING CARBON STEEL 316 S.S.
5 GUIDE 303 S.S. 3165.S.
81C-17-4 S.S. 815-17-4 S.S.
6 SPINDLE
83C-303 S.S. 835-316 S.S.
81C-TEFLON, KEL-F, 81S-TEFLON,KEL-F,
7 SEAT ORVESPEL ORVESPEL
83C-BUNA-N 835-BUNA-N
81 C-17-4 S.S. 815-17-4 S.S.
8 NOZZLE
83C-303 S.S. 835-316 S.S.
9 LOCKNUT CARBON STEEL 3165.S.
10 PRESS.ADJ. CARBON STEEL 3165.S.
11 CAP CARBON STEEL 316 S.S.
12 SEAL, SLOWDOWN TEFLON TEFLON
13 SLOWDOWN ADJ. CARBON STEEL 3165.S.
14 JAM NUT CARBON STEEL 316 S.S.
81C-17-4 S.S. 815-17-4 S.S.
15 RETAINER SCREW
83C-CARBON STEEL 835-316 S.S.
16 RETAINER 303 S.S. 3165.S.
81C-BUNA-N" 81S-TEFLON""
17 SEAL, NOZZLE
83C-BUNA·N" 835-BUNA-N"
18 SPLIT RING CARBON STEEL 316 S.S.
19 BONNET FLANGE CARBON STEEL 316 S.S.
20 FLANGE BOLTS CARBON STEEL 3165.S.
81C-BUNA-N• 81S-TEFLON ••
21 SEAL, BONNET
83C-BUNA-N" 835-BUNA-N"
22 BONNET CARBON STEEL 3165.S.
23 PRESSURE SEAL TEFLON TEFLON
'Teflon or Viton also available.
"Buna-N or Viton also available.

of that pressure, pounds per square inch, is called accu- ing from the pressure in the discharge system of the
mulation [10]. installed device [35]. This pressure may be only atmos-
pheric if discharge is directly to atmosphere, or it may be
Blowdown: blowdown is the difference between the set some positive pressure due to pressure drops of flow of
pressure and the reseating pressure of a safety or relief discharging vapors/gases (or liquids where applicable) in
valve, expressed as a percent of the set pressure, or the pipe collection system, which in turn may be con-
pounds per square inch [ 10]. nected to a blowdown or flare system with definite back-
pressure conditions during flow, psig (gauge). The pres-
Back Pressure: pressure existing at the outlet or dis- sure drop during flow discharge from the safety relief
charge connection of the pressure-relieving device, result- valve is termed "built-up Back pressure."