ISO 4126-6:2014 過度の圧力から保護するための安全装置—パート6：破裂ディスク安全装置の適用、選択、および設置 | ページ 6

3.1

bursting disc safety device

non-reclosing pressure relief device actuated by differential pressure and designed to function by the bursting of the bursting disc(s), and which is the complete assembly of installed components including, where appropriate, the bursting disc holder

3.2

bursting disc assembly

complete assembly of components, which are installed in the bursting disc holder to perform the desired function

3.3

bursting disc

pressure-containing and pressure-sensitive component of a bursting disc safety device

3.4

bursting disc holder

that part of a bursting disc safety device, which retains the bursting disc assembly in position

3.5

conventional domed bursting disc (also referred to as, forward acting)

bursting disc which is domed in the direction of the bursting pressure (i.e. where the bursting pressure is applied to the concave side of the bursting disc

Note 1 to entry: See ISO 4126‑2:2003, Figure 1).

3.6

slotted lined bursting disc

bursting disc made up of two or more layers, at least one of which is slit or slotted to control the bursting pressure of the bursting disc

3.7

reverse domed bursting disc (also referred to as, reverse acting)

bursting disc which is domed against the direction of the bursting pressure (i.e. where the bursting pressure is applied to the convex side of the bursting disc

Note 1 to entry: See ISO 4126‑2:2003, Figure 2).

3.8

flat bursting disc

bursting disc having one or more layers which is flat when installed. It may be made of a ductile or brittle material

3.9

graphite bursting disc

bursting disc manufactured from graphite, impregnated graphite, flexible graphite or graphite composite and designed to burst due to bending or shearing forces

3.10

specified bursting pressure

bursting pressure quoted with a coincident temperature when defining the bursting disc requirements (used in conjunction with a performance tolerance, see 3.14)

3.11

specified maximum bursting pressure

maximum bursting pressure quoted with the coincident temperature when defining the bursting disc requirements (used in conjunction with specified minimum bursting pressure, see 3.12)

3.12

specified minimum bursting pressure

minimum bursting pressure quoted with the coincident temperature when defining the bursting disc requirements (used in conjunction with specified maximum bursting pressure, see 3.11)

3.13

coincident temperature

temperature of the bursting disc associated with a bursting pressure (see 3.10, 3.11 and 3.12) and which is the expected temperature of the bursting disc when it is required to burst

3.14

performance tolerance

range of pressure between the specified minimum bursting pressure and the specified maximum bursting pressure or the range of pressure in positive and negative percentages or quantities which is related to the specified bursting pressure

3.15

operating pressure

pressure existing at normal operating conditions within the system being protected

3.16

relieving pressure

maximum pressure under discharge conditions in the pressurized system

Note 1 to entry: It can differ from the bursting pressure of the bursting disc.

3.17

relieving temperature

temperature under discharge conditions in the pressurized system

Note 1 to entry: It can differ from the coincident temperature specified for the bursting disc.

3.18

differential back pressure

differential pressure across a bursting disc in the opposite direction to the direction of the bursting pressure, which is the result of pressure in the discharge system from other sources and/or a result of vacuum on the upstream side of the bursting disc

3.19

vent area

cross-section area available for discharge of fluid as calculated by the manufacturer

Note 1 to entry: The calculated vent area should not exceed the cross-sectional area of the upstream piping, A₁.

3.20

batch

quantity of bursting discs or bursting disc safety devices made as a single group of the same type, size, materials and specified bursting pressure requirements where the bursting discs are manufactured from the same lot of material

3.21

bursting pressure

value of the differential pressure between the upstream side and the downstream side of the bursting disc when it bursts

3.22

stiffening ring

component of a bursting disc assembly used primarily for reinforcing bursting discs

3.23

back pressure support

component of a bursting disc safety device, which prevents damage to the bursting disc due to differential back pressure

Note 1 to entry: A back pressure support, which is intended to prevent damage to the bursting disc when the system pressure falls below atmospheric pressure, is sometimes referred to as a vacuum support.

3.24

coating

layer of metallic or non-metallic material applied to components of a bursting disc safety device by a coating process

3.25

lining

additional sheet or sheets of metallic or non-metallic material forming part of a bursting disc assembly or bursting disc holder

3.26

plating

metal layer applied to a bursting disc or bursting disc holder by a plating process

3.27

temperature shield

device which protects a bursting disc from excessive temperature

3.28

operating ratio

ratio between the operating pressure and the minimum limit of bursting pressure

Note 1 to entry: See Figure 1.

Note 3 to entry: In the case of a pressure system with a back pressure on the downstream side of the bursting disc, the operating ratio is the value of the differential pressure between the upstream side and the downstream side of the bursting disc divided by the minimum limit of bursting pressure expressed as a differential pressure.

3.29

bursting disc safety device discharge capacity

rate at which a bursting disc safety device can discharge fluid after bursting of the bursting disc

3.30

replacement period

time period beginning at the installation of a bursting disc assembly and ending at replacement

3.31

pressure relief system

system intended for the safe relief of fluids from pressure equipment for prevention of excessive pressure

Note 1 to entry: It can consist of equipment nozzle, inlet piping, pressure relief device(s) and discharge piping to atmosphere/collecting vessel/header.

3.32

discharge coefficient

coefficient which determines reduction of theoretical discharge capacity of a pressure relief system by the simplified approach (see C.2) which incorporates a burst bursting disc, forming part of a bursting disc safety device

Note 1 to entry: It is denoted by the symbol α.

3.33

flow resistance factor

K_R

dimensionless expression of the velocity head loss attributed to the presence of a bursting disc safety device in a piping system

3.33.1

flow resistance factor

K_RG

flow resistance of a bursting disc safety device when burst with compressible fluid in contact with the upstream side of the bursting disc

3.33.2

flow resistance factor

K_RL

flow resistance of a bursting disc safety device when burst with incompressible fluid in contact with the upstream side of the bursting disc

3.33.3

flow resistance factor

K_RGL

flow resistance of a bursting disc safety device when burst with either compressible or incompressible fluid in contact with the upstream side of the bursting disc

3.34

base pressure

pressure recorded at the pipe inlet of the bursting disc flow test system

3.35

base temperature

temperature recorded at the pipe inlet of the bursting disc flow test system

3.36

maximum allowable pressure

p_S

maximum pressure for which the equipment is designed, as specified by the manufacturer

3.37

non-fragmenting bursting disc safety device

bursting disc safety device that is designed to retain the petals produced during activation