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There is no recommended time for a disk to be replaced. User experience is the best teacher. For example, if you find a trend that your disks rupture after a period of 6 to 8 months in service, to avoid costly down time, it may be suggested to change the disks out every 5 months. BS&B offers a service to assist in the customer’s determination of a disk’s service life so you may optimize service life of the disk without the worry and hassle of change out. We stand ready to test unburst disks removed from service.
In general, most tension-loaded or conventional style disks require a vacuum support to withstand full vacuum. Reverse buckling disks will "withstand" or (resist) full vacuum without the use of a vacuum support (Refer to catalogs for specific products). A common exception for reverse buckling disks is the type ECV™, which requires a vacuum support to allow the disk to withstand full vacuum. Vacuum resistance is the maximum vacuum that a disk is rated to hold. This is not the same as burst pressure.
Every order is supplied with Installation Instructions for proper installation. In general, the sensor is placed between the outlet flange of the holder and the downstream companion flange. For specific instructions please request the Installation Instructions for the specific product type.
Pounds per square inch differential.
Yes! Contrary to the sales rhetoric of some manufacturers, installing a rupture disk with the manufacturer’s recommended torque can significantly improve the rupture disk’s precision and service durability. Although some disks are more forgiving of improper or unbalanced torque, each is an instrument and should be installed with proper torque.
Clearly the best advice we can offer is to be fully rupture disk "literate". Due to the complexity of the products, that is not always easy. BS&B offers "no charge" engineering and technical seminars to educated personnel on rupture disk technology and disk selection. Additionally, we encourage you to contact our factory-trained sales representatives or the factory for assistance. We are pleased to help.
We recommend the practices defined by the ASME Code and API. The rupture disk and the relief valve should be "close coupled" (No intervening spool piece). The disk and relief valve should be set at the same nominal pressures. The cavity between the rupture disk and the relief valve must be monitored to ensure there is no pressure in the cavity. Since rupture disks are differential pressure devices, any pressure downstream of the rupture disk is considered a "back pressure" and will prevent the disk from opening at its marked burst pressure. See specific details on the Code or request assistance from your local BS&B factory-trained sales representative.
A "safety head" is the BS&B nomenclature for a rupture disk holder. The ASME Code defines a "rupture disk device" as a rupture disk and the holder into which the disk is installed. The "safety head" is the portion of the device which ensures the proper performance of a rupture disk and accommodates its installation into a piping scheme.
“Burst tolerance" is the allowable deviation in actual burst pressure from the "marked burst pressure". Typically expressed as a percentage (or in "psig"), a disk properly specified and installed should always burst within the "tolerance" for the particular type, style, and rated pressure of the disk.
“Manufacturing design range" is a "premanufacturing agreement" between BS&B and the customer for "economy". It is a "range" of pressures within which the marked burst pressure of a lot must fall. If a customer requests a 100psig rupture disk with a manufacturing design range of 10%, the customer is allowing BS&B to provide to him, a lot of disks, the marked burst pressure of which, must be between 90psig and 100psig. Should the customer request a 5% manufacturing design range, BS&B would be obligated to provide a lot of disks which must have a marked burst pressure anywhere between 95psig and 100psig. Manufacturing design ranges may be indicated as a percentage or in psig. Should the customer request to received a lot of disks marked precisely at his requested pressure, a 0% (zero percent) manufacturing design range would be requested.
The "maximum operating pressure" is the maximum system pressure to which the disk may be exposed without causing premature metal fatigue to the rupture disk. If a particular style of rupture disk rated at 100psig has a 90% maximum operating pressure, the disk should not be exposed to greater than 90psig. Maximum operating pressures are typically between 50% and 100%. Exposing a particular style of disk to greater than the manufacturer’s published maximum operating pressure can significantly shorten the service life of the disk.
Also called a "compression-loaded" rupture disk, a "reverse-buckling" rupture disk is one which is installed with the crown of the disk (convex side) facing the system pressure.
Some rupture disk holders are held together by "assembly lugs" on the side of the holders until they may be installed into the piping scheme companion flanges. A "pre-torqued holder" is equipped with recessed capscrews which not only hold the two halves of the holder together but also provide a precise mechanism with which to apply the manufacturer’s recommended torque value to the disk. The disk and holder (rupture disk device) may be precisely assembled in the convenience of the maintenance or instrument shop assuring proper performance of the disk device in service.
Yes. The ASME Code recognizes the use of a rupture disk as a primary relief device.
Several answers apply to this question. First, should the rupture disk protecting a relief valve from the process not rupture from exposure to excess process pressures, the relief valve is maintained in a clean, pristine condition. Valve maintenance costs are, accordingly, dramatically reduced. Second, isolation of relief valves with rupture disks is environmentally smart. The "bubble tight seal" of a rupture disk prevents valve leak, seep, weep, and chatter. For more details on the advantages of relief valve isolation, see BS&B Catalog #77-1006.
When a rupture disk is used to isolate a relief valve from the process environment, the ASME Code requires the cavity between the rupture disk and the valve seat to be monitored. Since a rupture disk is a "differential" pressure relief device, any pressure in the cavity between the rupture disk and the relief valve seat will act to elevate the burst pressure of the rupture disk. A "tell-tale" assembly is a method to satisfy this Code requirement. Other methods may also be used to fulfill this requirement. (See ASME Code)
NO! Consult BS&B catalog literature or contact your local factory-trained sales representative for specific service applications for which disks may be used. BS&B does offer a broad scope of rupture disks which are suitable to both gas and liquid applications.