This International Standard gives requirements and recommendations for the design, materials, fabrication, inspection, testing and preparation for shipment of aircooled heat exchangers for use in the petroleum and natural gas industries. This Standard is applicable to air-cooled heat exchangers with horizontal bundles, but the basic concepts can also be applied to other configurations.

This edition of Std 661 is an identical national adoption of ISO 13706, Petroleum and natural gas industries-Air cooled heat exchangers.