Solid Metal Rupture Disk (Bursting Disc)

Select from the following topics:
Benefits
How a Tension-Loaded Disk Works
Standard Manufacturing Ranges
Rupture Tolerance
Specifications
Holder Requirement
Linings
Type BV Disks for Vacuum
Type BR Disks for Low Burst Pressures
Use in Elevated or Cold Temperature Service
Safety Heads for Type B Disks

Benefits

The vents may be supplied with the following:

• Electrical sensor to warn of open vent
• Locking enclosure
• Sealed enclosure for corrosive environments
• Activated reclosing

How a Tension Loaded Disk Works

As the pressure increases on the tension-loaded disk, the seating design allows the dome to thin out until it can no longer withstand the pressure. The disk ruptures. Metal segments fold back against the walls of the fitting in an irregular pattern to provide a full opening. The ultimate tensile strength of the metal determines its failure point when loaded in tension.

Standard Manufacturing Ranges

When you order a rupture disk (bursting disc), a manufacturing range is automatically assigned to the burst pressure you specify. The following table gives the standard manufacturing ranges. A manufacturing range eliminates the necessity for the manufacturer to stock all possible thicknesses of all materials, nearly 100,000 thicknesses in all, to make all burst pressures.

For example, if you order a B Disk to burst at 80 psig, BS&B will enter the order to the shop with the standard manufacturing range (+9,-5), or 75 to 89 psig. BS&B will try for your requested pressure of 80 psig, but will ship the lot of disks if the marked pressure falls between 75 to 89 psig. Once the disk is rated and marked 78 psig, the burst tolerance of ±5% now applies to this stamped pressure.

The standard manufacturing ranges shown in the following table can be reduced by 1/2 or 1/4 for an additional cost. Hastelloy C-276 / Alloy C-276 is available only with standard manufacturing range and 1/2 range.

Standard Manufacturing Ranges for Solid Metal Disks Before the Disk is Stamped

The Type B Rupture Disk (Bursting Disc) must be used in BS&B rupture disk (bursting disc) holder types FA, SA, SF, or UA or other types recommended by and manufactured by BS&B. Substitution of either rupture disk (bursting disc) or rupture disk (bursting disc) holder not manufactured by BS&B not only may affect the burst pressure or opening characteristics of the disk, it also voids BS&B warranty.

Linings and Coatings

1. All liners have passed a spark test to assure pinhole-free condition.
2. Protective ring is required for solid metal disks with fluoropolymer lining on both sides in all disk materials except aluminum. Specify Type BR, BRV, or BRSV.

Lining Specifications:

Linings:

Standard materials: FEP plastic (Teflon®*)
Maximum Temperature: 400 °F
Special materials: TFE plastic (Teflon®*)
Maximum Temperature: 500 °F
(Teflon® generally is used. Other appropriate fluorpolymers may be supplied. Teflon® is a registered trademark of Dupont.)
Coatings:Vinylite, a mild corrosion retardant for disk metal, can be applied to one or both sides of disk.
Maximum temperature: 150 °F (66 °C)

Type BV Disks for Vacuum Applications

If backpressure on convex (atmospheric) side of the disk ever exceeds the pressure applied to the concave (pressure) side of the disk, a vacuum support may be required. Supports are not required for all disks. Consult the table below

Type BR Disks when Disk Burst Pressure is Near the Minimums

If the pressure rating for a Type B Rupture Disk (Bursting Disc) is at or near the minimum, a thin disk is dictated and a BR protective ring is required.

Consider using a BR protective ring for pressures below those listed in the following table.

All ratings are psig.

Since seating area of disk should be free of any deformity or penetration by a foreign substance that might adhere to lip of flange holder, a heavier gauge metal BR ring should be mounted to one or bother sides of the disk in the seating area to provide support and protection. When one ring is involved, the assembly is called Type BR Rupture Disk (Bursting Disc). When two rings are used, the assembly is called Type BRR Rupture Disk (Bursting Disc). If a vacuum support is required, the BR ring is used only on atmospheric side of disk. This assembly is called Type BRV Rupture Disk (Bursting Disc).

A support ring may provide adequate structural strength for the rupture disk, eliminating the need for a vacuum support. See table below for when a BR can be used instead of a BRV.

When Support Ring will Withstand Full Vacuum
Minimum burst pressure at which Types B and BR Disks with adequate support ring will withstand full vacuum.

BR ring:

Standard metal: 316 Stainless Steel
Special metals: Inconel, Monel, Nickel
Hastelloy B and C, 276 Titanium and Tantalum.
Aluminum ring is standard on Aluminum disks.

In most applications involving vacuum, the term "commercial vacuum" is used. If extremely high vacuum is involved--in the micron range--seating of disk may require a soft gasket ring mounted to the process side of support. The assembly of disk support and soft gasket ring is called Type BSV Rupture Disk. If a BR ring is also attached to atmospheric side of disk, the assembly is called Type BRSV Rupture Disk (Bursting Disc). Vacuum grease may also be applied to the soft ring-seating surface to provide additional tightness when high vacuum is encountered.

Soft gasket ring:
Standard materials: Aluminum, or Teflon
Special Materials: Silver or Nickel

Elevated or Cold Temperature Service

To determine the burst pressure rating at elevated or cold temperatures, a temperature correction factor must be applied to ratings at 72^o .

The temperature conversion table applies only to BS&B Type B series Solid Metal Disks and cannot be used for Type D Composite Disks or reverse buckling disks. Data used to develop the table has been obtained from reliable sources, however BS&B does not warrant the figures nor will BS&B be held liable for any use to which the figures may be put.

Temperature correction factors are shown in "percent from rupture pressure at 72^o F." Values are approximate and are based on disk metal at temperatures listed.

When selecting Type B Disks for elevated or cold temperature service, check installed conditions whenever possible to determine actual temperatures. You will be able to specify disks with greater burst accuracy.

Recommended maximum temperatures for metals used in standard Type B Disks

How to Use Temperature Conversion Table

To determine estimated rupture pressure of a disk at temperature other than 72 °F, multiply rated pressure at 72°F by the temperature correction factor shown for the disks metal.

EXAMPLE
What is rupture pressure at 500 °F of a nickel disk rated 300 psi at 72 °F?

1. Consult temperature conversion table. Correction factor for nickel disk at 500 °F is 86%.
2. Multiply disk rating at 72 °F by correction factor: 300 X 0.86 = 258

Rupture pressure of a nickel disk rated 300 psi at 72 °F is 258 psi at 500° F.

Temperature Conversion Table for Type B Rupture Disks Only

Safety Heads for Type B Rupture Disks

QUIK-SERT or UNION TYPE

QUIK-SERT Safety Heads reduce downtime, assure proper seating of rupture disk (bursting disc).

BS&B Bolted Type Safety Heads are normally compatible with ANSI (ASA) pipe flanges and the flanged connections used on most pressure vessels. Safety Head flanges feature angular seating design to accommodate Type B Solid Metal Disks.

The BS&B QUIK-SERT is a reduced outside diameter, flat-faced flange assembly (FA-7R) that nests between the studs of two ANSI (ASA) flanges. Flanges and rupture disk (bursting disc) are pre-assembled (-in your shop, not at the factory) to assure proper installation of disk. The complete safety Head can be removed without removing discharge piping.

Union Type Safety Heads are used in applications when space is limited and where quick or frequent change out of rupture disk (bursting disc) may be necessary. Standard sizes are _", 1", 1 _", and 2" I.D. BS&B Union Type Safety Head design features angular seating of rupture disk (bursting disc) and will accept Type B Solid Metal Disks