Page 241 - Valve Selection Handbook

228 Valve Selection Handbook

For a given thickness and strength of the material, the burst pressure is
controlled by a combination of slits and tabs. By this construction, the
rupture disc for low burst pressures can be manufactured from thicker
materials that permit the operating ratio to be raised to 80%.
The rupture discs are generally suitable in the lower pressure regions
only. They may be used in gas and liquid service and permit pulsating
pressure service. The discs are also non-fragmenting when used in con-
junction with a fluorocarbon seal member.

Scored forward-domed rupture discs. These are solid forward-domed
rupture discs that are cross scored on the convex side of the dome, as
shown in Figure 6-10. Scoring allows the disc to be made of thicker
material that allows the operating ratio to be raised to 85%. The discs
may be used in either gas or liquid-full service and offer a good service
life in cycling service. The score lines provide a predictable opening pat-
tern so that the disc can be manufactured to be non-fragmenting. Within
the lower burst pressure range, however, the rupture disc must be sup-
ported against full vacuum.
A special field of application of scored forward-acting rupture discs is
in polymer service. The problem of polymerization is minimized by
avoiding a crevice between the rupture disc and inlet holder component

Figure 6-10. Cross-Scored Forward-Acting Rupture Disc. (Courtesy of Anderson,
Greenwood & Company.)