Page 435 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Process Safety and Pressure-Relieving Devices 401

Pr988ure-Rellevlng Devices

Spindle
Test Gag Spindle Lift Nu!
Cap Forked Lever Pin
.....,._,,,,,, Spindle ���
Adjusting Bolt Lever Adjusting Boll
Adj. Bolt Nut Adj. Ball Lock Nut
Gasket Cap Set Screw
Bor,net

REGULAR llftlMG
SCREWED CAP GEAR
Type A (Std.) type C
SCREWED CAP AND
TEST ROD
Type B

PACKED LIFTING GEAR
PACKED LIFTING ANDTESTROO
GEAR (Voi...e not ohowo uo;;..t)
Type D Typ• E
Figure 7-18. Accessories for all types of safety relieving valves. Courtesy of Crosby-Ashton Valve Co.

Special Valves-

a. Internal spring safety relief valve
CAP --------�..;. b. Power actuated pressure relief valve
SPINDLE NUT
ADJ BOLT BEARING c. Temperature actuated pressure relief valve
These last three are special valves from the viewpoint of
chemical and petrochemical plant applications, but they
can be designed by the major manufacturers and instru-
mentation manufacturers as these are associated with
instrumentation controls. Care must be taken in the sys-
tem design to make certain it meets all ASME code
requirements.

Rupture Disk
DISC NUT----..._loi-k-·-""
DISC HOLDER
DISC INSERT A rupture disk is a non-reclosing thin diaphragm
GUIDE (ADJ) RING (metal, plastic, carbon/graphite (non-metallic)) held
between flanges and designed to burst at a predeter-
mined internal pressure. Each bursting requires the
NOZZLE RING ----- installation of a new disk. It is used in corrosive service,
....
NOZZLE------- toxic or "leak-proof' applications, and for required burst-
BODY-------.
ing pressures not easily accommodated by the conven-
Figure 7-2. Safety valve. Courtesy of Crosby-Ashton Valve Co. tional valve such as explosions. It is applicable to steam,