Metric Bolt Temperature Rating

Fire Performance

• Temperature ratings of metric bolts are used in determining their expected performance during a fire. Metric bolts must carry at least the design load at the expected temperature of a fire to prevent building collapse. European Union standards for the fire performance of bolts are specified in Annex D of Eurocode EN 1993-1-2. According to “Designers Guide to EN 1991-1-2, EN 1992-1-2, EN 1993-1-2 and EN 1994-1-2,” “the aim of the design calculations is to ensure that a structural member has sufficient load-carrying capacity at elevated temperatures to resist the applied load in a structural member at the fire limit state.” European fire rating calculations and European structural standards are in metric units.

European Standards

• European standards give temperature ratings for metric bolts in Celsius. EN 1591 is the horizontal European standard for bolted joints. EN 13445 is the European equivalent to the American Society of Mechanical Engineers (ASME) boiler and pressure vessel code, including acceptable temperature and pressure ratings for metric bolts used in high-pressure vessels and piping. European standards require that bolts and flange materials have coefficients of thermal coefficient within 10 percent of each other at 20 degrees Celsius. According to “Guide to European Pressure Equipment,” European standards decree that “the difference between the mean temperatures of the bolts and the flange does not exceed 50 degrees Celsius in any condition.”

Water Piping

• The ASME creates standards for pressure vessels, pipes and connecting hardware like bolts. The American Water Works Association (AWWA) issues design recommendations for water and waste-water piping, including the bolts and flanges used with water piping. The American National Standards Institute (ANSI) International mediates these standards, often selecting standards for bolts based on their application. ANSI/AWWA standards define the acceptable specifications for piping and connecting hardware in both American and metric units. ANSI/AWWA standards include metric and American temperature-pressure ratings. “Ductile-Iron Pipe and Fittings,” by the American Water Works Association, states “ASME/ANSI B16.1 flanges carry a pressure-temperature rating for service at ambient and elevated temperatures, whereas ANSI/AWWA C110/A21.10, C153/A21.53 and C115/A21.15 flange ratings are for water at ambient temperature.”

Electrical Connections

• Split bolt connectors and wire nuts hold wiring together. Metric split bolt connector temperature ratings are given in degrees Celsius. A split bolt connector’s temperature rating must be equal if not higher than the temperature rating of the wire it connects. If the metric bolt connector has a lower temperature rating than the wire, it may burn up.