API RP 576-2000 pdf free download
API RP 576-2000 pdf free download.Inspection of Pressure-Relieving Devices.
4.8 PRESSURE AND/OR VACUUM VENT VALVE A pressure and/or vacuum vent valve (also known as a pressure and/or vacuum relief valve) is an automatic pressure or vacuum-relieving device actuated by the pressure or vac- uum in the protected equipment. A pressure and/or vacuum vent valve falls into one of three basic categories: a. Weight-loaded pallet vent valve, as shown in Figure 10. b. Pilot-operated vent valve, as shown in Figure 7. c. Spring and weight-loaded vent valve, as shown in Fig- ure 11. 4.8.1 Applications Pressure and/or vacuum vent valves are normally used to protect atmospheric and low-pressure storage tanks against a pressure large enough to damage the tank. Single units com- posed of both pressure vent valves and vacuum vent valves are also known as conservation vent valves, and are normally used on atmospheric storage tanks containing materials with a flash point below 100°F (38°C). However, they may also be used on tanks storing heavier oils (see API Bul 2521 and API Std 2000). 4.8.2 Limitations Pressure and/or vacuum vent valves are generally not used for applications requiring a set pressure greater than 15 lbf/in. 2 (103 kPa). 4.9 RUPTURE DISK DEVICE The combination of a rupture disk holder and rupture disk is known as a rupture disk device. A rupture disk device is a non- reclosing pressure relief device actuated by the static differen- tial pressure between the inlet and outlet of the device and designed to function by the bursting of a rupture disk. A rupture disk device includes a rupture disk and a rupture disk holder (see Figure 12). a. A rupture disk is a pressure containing, pressure and tem- perature sensitive element of a rupture disk device. Rupture disks may be designed in several configurations, such as flat, domed (prebulged), or reverse acting. The rupture disk holder secures the disk in place.
4.9.1.2 Scored Tension-Loaded Rupture Disk The scored tension-loaded rupture disk is designed to open along scored lines (see Figure 14). This type of disk is designed to allow a closer ratio (generally 85%) of system operating pressure to disk burst pressure. Because the score lines control the opening pattern, this type of disk is normally nonfragmenting. The scored tension-loaded rupture disk is manufactured from thicker material than is used for unscored disks for the same burst pressure. The disk is mechanically scored to control the burst pressure and burst pattern. The increased material thickness of the disk provides additional resistance to mechanical damage; in most cases, the disk will withstand full vacuum without the addition of a separate vac- uum support. 4.9.1.3 Composite Rupture Disk A composite rupture disk is a flat or domed metallic or nonmetallic multi-piece construction disk. The domed com- posite rupture disk is designed to burst when it is overpres- sured on the concave side. The flat composite rupture disk is designed to burst when it is overpressured on the side desig- nated by the manufacturer. The domed composite rupture disk, available in flat-seat or angular-seat design, permits typical operation to 80% of the rated burst pressure under limited pressure cycling and tem- perature variations. The burst pressure is controlled by the combination of a slit-top section and a metallic or nonmetal- lic seal member under the top section. Composite rupture disks are generally available in burst pressures lower than those of the conventional domed rupture disks and may offer a longer service life as a result of the corrosion resistant prop- erties of the seal material selected. The slit-top section pro- vides a predetermined opening pattern for the rupture disk and is designed to minimize fragmentation when the top sec- tion is supplied with a nonmetallic seal. As with the conven- tional domed rupture disk
