Specifications Rupture disk

Determine size and specifications for all safety relief valves and/or rupture disks for process safety relief (including run-a-way reactions) and relief in case of external fire. 

Although not specifically recognized in the tides of the codes, the rupture disk as a relieving device, is, nevertheless, included in the requirements as an acceptable device. 

A single rupture disk can be used as the only overpressure protection on a vessel or system (Figure 7-10). The disk must be stamped by the manufacturer with the guaranteed bursting pressure at a specific temperature. The disk must rupture within +5% of its stampied bursting pressure at its specified burst temperature of operation. The expected burst temperature may need to be determined by calculation or extrapolation to be consistent with the selected pressure. 

Note that in lieu of testing, Par (b) 2 and (b) 3 above allows the use of a capacity factor of 0.80 as a multiplier on the stamped capacity of the spring loaded safety relief valve (nozzle bpe). Some manufacturers test specific valve/rupture disk combinadons and determine the actual capacity factor for the combination, and then use this for the net capacity determination. See Figures 7-10, 7-11, 7-12, 7-13A and 7-13B. c. A rupture disk de ice may be installed on the outlet side of a spring loaded safety relief valve... 

V Tiere the pressure relief valve is used in series with a rupture disk, a combination capacity of 0.8 must be applied to the denominator of the referenced equations. Refer to a later section this text or to specific manufacturers. 

When ordering rupture disks, the following information and specifications should be given to the manitfacturer. 

There have been at least six different formulas proposed and used to determine the proper and adequate size of rupture disk openings for a specific relieving condition. The earlier studies of Sylvander and Katz [25] led to the development of the ASME and API recommendations. This approach assumes that a fire exists under or around the various vessels in a process. This fire may have... 

Sonic flow, safety relief, 438 Rupture disk, 460, 461 Sub-sonic flow, 461 Sonic or critical flow, 115, 125 Calculations, 125 Velocity, 126 Specific speed, 194-197 Impeller designs, 194 Upper limits, chart, 195-197 Specifications,... 

Rupture disk, 455 Safety relief valves, 454, 467, 481 Specifications, centrifugal pumps, 209 Spray nozzle particle size, 225 Standards and Codes, 31, 32, 33 Static electricity, 536 Static mixing, 332 Applications, 336 Calculations, 337, 338 Materials of construction, 337 Principles of operation, 335 Type of equipment 334-338... 

For all other conditions EF has to be determined by tests (Fig. 23-13). EF and therefore the effective vent area Aw of a non-inertia-free explosion device are smaller than the venting efficiency of an inertia-free vent device (specific mass < 0.5 kg/m2) with the same vent area. Therefore, such devices need testing to determine the mechanical strength before actual use, and the EF or the pressure rise, respectively, has to be chosen relative to the Predmax of the rupture disk of the same area. 

Coverage confirmation, time to provide full foam coverage, leaks, blockages, rupture disk function, age of foam, portioning calibration mechanisms, performance of delivery pumps or bladder tanks, foam drain times, etc. should be verified for each unique system. NFPA 11 provides guidance in the specific test requirements for several characterisitic foam systems. 

An 800-gal reactor containing a styrene mixture with a specific heat of 0.6 cal/gm °C has a 10-in. rupture disk and a vent line with equivalent length = 400. The vessel MAWP is 100 psig and the rupture disk set pressure is 20 psig. The styrene mixture had a self-heat rate of 60°C/min at 170°C as it is tempered in a DIERS venting test. Determine the allowable reactor mixture charge to limit the overpressure to 10% over the set pressure. 

Commonly reported near misses include such events as exceeding operating limits, a release of a chemical or other hazardous substance that does not meet the threshold for a process safety incident metric, activation of relief valves, interlocks, or ruptured disks. Companies may establish near-miss metrics based on the specifics of their operation, based on their observations of frequent upsets or failures, or to track and correct observed unsafe practices or behaviors. 

An alternate pressure relief valve with a marked set pressure not to exceed 150% of the DOT service pressure may be used in lieu of the rupture disk device if the flow capacity required for relief devices on TC/DOT specification 4L insulated cylinders is provided at 120% of marked set pressure. Installation must provide for ... 

The rupture disk is the operating part of the pressure relief device and, when installed in a proper rupture disk holder, is designed to burst at a predetermined pressure to permit discharge of the cylinder contents. Such disks are usually made of metallic materials and may be of flat, preformed, reinforced, grooved, or scored construction. Nonmetal-lic materials are also used for specific applications. 

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