Section XIII contains rules that provide the requirements for the overpressure protection of pressurized equipment such as boilers, pressure vessels, and piping systems. Overpressure protection methods include:

• Releasing excess pressure by use of pressure relief devices
• Applying controls to prevent an increase in pressure (overpressure protection by system design)
• Using a combination of the above two methods

The referencing Code or Standard specifies the objectives of the overpressure protection and acceptable methods to achieve it. Where a pressure-releasing overpressure protection method is specified, the referencing Code or Standard identifies the permissible devices based on this Section’s rules for devices to be marked with the Certification Mark and appropriate Designator (e.g., HV, UV, UD).

This Section includes:

• Requirements relating to pressure integrity and performance governing the construction and installation of pressure relief devices. Construction requirements include materials, design, manufacture, examination, inspection, production testing, and certification. Installation requirements address only the variables that affect the performance and pressure-relieving function of the devices, including the inlet and outlet piping.
• Requirements for conducting tests and analyses to determine the performance of pressure relief devices. These include rules for device-type certification of relieving capacity and/or flow resistance and production testing for new pressure relief devices.
• Requirements for the use of overpressure protection by system design.
• Mandatory Appendices that address specific subjects not covered elsewhere in this Section.
• Nonmandatory Appendices that provide information and suggested best practices.

Careful application of this Section will help users to comply with applicable regulations within their jurisdictions, while achieving the operational, cost and safety benefits to be gained from the many industry best-practices detailed within these volumes.