ISO 15665:2003 defines the acoustic performance of three classes (classes A, B and C) of pipe insulation. It also specifies three types of construction that will meet these acoustic performance classes. Furthermore, it defines a standardized test method for measuring the acoustic performance of any type of construction, thereby allowing existing and new insulation constructions to be rated against the three classes.

ISO 15665:2003 is applicable to the acoustic insulation of cylindrical steel pipes and to their piping components. It is valid for pipes up to 1 m in diameter and a minimum wall thickness of 4,2 mm for diameters below 300 mm, and 6,3 mm for diameters from 300 mm and above. It is not applicable to the acoustic insulation of rectangular ducting and vessels or machinery.

ISO 15665:2003 covers both design and installation aspects of acoustic insulation and provides guidance to assist noise control engineers in determining the required class and extent of insulation needed for a particular application. It gives typical examples of construction methods, but the examples are for information only and not meant to be prescriptive.