Attachment apparatus and method for interlocking attachment of a scraper blade with a drive shaft of a scraped surface heat exchanger includes a blade having dual attachment beams and a central locking member, and at least one pin having dual fingers each for interlocking with a respective attachment beam. The blades feature protective supporting nubs that are outwardly facing from the blade and located proximate to the mounting locations of the blade to provide a supporting rest for the drive shaft pin and blade assembly as it is slid into or out of its outer housing tube.