Specifies the ball pressure test as a method for testing parts of non-metallic materials for resistance to heat. Includes the following significant technical changes from the previous edition: a) The post test water immersion time (see 7.1) has been changed. b) dimension d is no longer the diameter but the greatest dimension of the indentation (see 7.2 and Figure 2). c) The stated accuracy of the measuring table has been deleted (see 4.4). Has the status of a basic safety publication in accordance with IEC Guide 104 The contents of the corrigendum of February 2006 have been included in this copy.