Selection and Sizing of Rupture Discs - a PDH Online Course for Engineers and Surveyors

Selection and Sizing of Rupture Discs

Course Outline

This course covers the non-reclosing type of pressure relief devices known as rupture discs. It reviews the codes that govern rupture discs and the standard formulas and equations that are used to determine their proper selection and sizing. The course is directed toward Chemical and Mechanical Engineers in the process industries but should provide appeal to general practitioners as well. As a prerequisite, the student should have a basic familiarity with pressure vessels and piping systems.

This course includes a multiple choice quiz at the end.

Learning Objective

At the conclusion of this three hour course, the student will learn the following regarding the selection and use of rupture discs:

ASME Code rules for their use in overpressure protection;
Disc terminology and device certification; and
Performance requirements and sizing methodologies.

Course Content

Rupture discs are non-reclosing pressure relief devices designed to provide overpressure relief in chemical and petrochemical processing applications. Their purpose is to protect these systems from excessive pressures cause by mechanical malfunctions, runaway chemical reactions, and internal or external fires. Rupture discs are available in a wide range of materials, sizes, and configurations.

The rupture disc consists of a thin frangible disc, usually of metal, held between specially machined flanges and of such a thickness, diameter, and material that it will rupture at a predetermined pressure.

The disc materials in use are aluminum, copper, silver, platinum, palladium, nickel, stainless steel, Monel®, and Inconel®. The selection of the metal is based on corrosion, temperature, and rupture pressure. Since the metal disc is thin, the stresses are relatively high, and no corrosion allowance is allowed. Consequently, the disc material must be more corrosion-resistant than the metal from which the pressure vessel is constructed. As an alternative, coatings and linings of lead, vinyl resins, Teflon®, or other materials may be used to protect the discs against corrosion.

There should be sufficient margin between the normal operating pressure and rupture pressure of a disc so that the metal is not fatigued by pressure variation or stressed to a point where it will take a permanent set. Such stretching will cause a disc to rupture below its original design rating. Graphite or composite material rupture discs should be considered for use where pulsating pressures are encountered. Graphite rupture discs are essentially unaffected by temperature changes.

For proper specification of rupture discs, it is essential to know the actual temperature that will be encountered at the location of the disc. On first thought, it might seem logical to specify rupture discs having a rated bursting pressure equal to the maximum allowable working pressure and at a temperature equal to the operating temperature of the system that is being protected. However, in some high-temperature installations the rupture disc rarely approaches the operating temperature. The use of rupture discs incorrectly rated for a high operating temperature could lead to serious consequences.

For the balance of this course, you will be deep hyper-linked to a portion of the Fike Corporation website, fike.com, for an educational session. Specifically, you are directed to Fike Corporation Technical Bulletins TB8100, ASME Code and Rupture Discs, and TB8102, Rupture Disc Sizing, at http://www-eng.lbl.gov/~shuman/XENON/REFERENCES&OTHER_MISC/tb8100.pdf and http://forums.fike.com/dslookup.php?datasheet=TB8102,respectively.

At the above URLs you will be presented with the following course content sections:

ASME Code Concerning Rupture Disc Devices
ASME Code Rupture Disc Terminology
Rupture Disc Performance Requirements
Rupture Disc Sizing Methodologies
Manufacturer Certification
Rupture Disc Device Certification
Rupture Disc Marking Requirements
ASME Application Requirements
Detailed Rupture Disc Sizing Methods and Examples

Additional Resources

The student should read/review the latest edition of the ASME Code, Section VIII, Division 1, paragraph UG-127 "Nonreclosing Pressure Relief Devices" when designing pressure relief systems and selecting, sizing, and specifying rupture discs.

The American Society of Mechanical Engineers
United Engineering Center
345 East 47th Street
New York, N.Y. 10017
www.asme.org

American Petroleum Institute
2101 L Street Northwest
Washington, D.C. 20037
www.api.org

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.org or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.