This specification provides design and construction criteria for large diameter flanges for use in high temperature, low pressure service such as internal combustion engine exhaust and forced ventilation systems. The flanges shall be classified according to types as follows: Type I and Type II. Number of holes, hole diameter, and bolt circle are identical for both Type I and Type II flanges. Drilling of flanges shall be in accordance with the specified requirements.

1.1 This specification provides design and construction criteria for large diameter flanges sizes 14 NPS to 144 NPS, for use in high temperature (1000 °F), low pressure service (25 psig), such as internal combustion engine exhaust and forced ventilation systems.

1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.