Chemical Engineering June 2016 - 39

tions. during the manufacturing process,
several pieces from each lot are
forced to burst as a test, to ensure
that the manufactured lot meets the
specifications.
rupture discs have evolved considerably
since their first use in the 1930s.
nonetheless, most of the older designs
are still in use today. compared to modern
designs, older rupture disc designs
have lower performance capabilities,
reduced repeatability and are more difficult
to accurately calibrate to a specific
burst pressure.
While they may be less expensive
than the newer high-performance designs,
they may bring tradeoffs in
performance or reliability.
in many
cases, a facility's particular management
of change (Moc) protocol
prevents upgrading to modern
technology. When this happens, users
often become accustomed to tolerating
the poor performance of these
outdated designs.
understanding the terms that are
used to describe rupture disc performance,
and the technology options
Table 1. ManufacTuring design range
Customer request: Burst pressure of 100 psig @72oF
Rupture discs will be marked somewhere between the minimum and maximum possible marked burst
pressure
Manufacturing design range +10 to -5 psig -10%
Maximum possible
marked burst pressure
Minimum possible
marked burst pressure
110 psig
@72oF
95 psig
@72oF
100 psig
@72oF
90 psig
@72oF
Customer request: Burst pressure of 100 psig @72oF
Burst pressure
Maximum acceptable burst pressure
Minimum acceptable burst pressure
-5%
100 psig
@72oF
95 psig
@72oF
Table 2. bursT pressure Tolerance
35 psig (≤40 psig)
35 + 2 = 37 psig
35 - 2 = 33 psig
Table 3. operaTing raTio
Rupture disc with a marked burst pressure (BP) of 100 psig @72oF
Operating ratio
70%
Maximum operating pressure
(If based on marked BP)
Maximum operating pressure
(If based on marked BP minus burst tolerance)
that are available to meet the increasing
demands placed upon these important
safety devices can give engineers
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Circle 11 on p. 74 or go to adlinks.chemengonline.com/61496-11
ChemiCal engineering www.Chemengonline.Com june 2016
39
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70 psig
80%
80 psig
90%
90 psig
95%
95 psig
66.5 psig 76.0 psig 85.5 psig 90.3 psig
100 psig (>40 psig)
100+5%=105 psig
100-5%=95 psig
0%
100 psig
@72oF
100 psig
@72oF
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Chemical Engineering June 2016

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