Magnetic Inspection for Assessing the Uniformity of Flange Joints Bolt Tightening

Flange joints refer to the most widespread detachable joints used in various industries. Such joints should be strong, durable, and leak proof. Compliance with these requirements depends largely on the uniformity of bolt tightening. In flange joints, it is necessary to provide that all bolts (pins) are tightened with equal force. Nonuniformity of bolt tightening could lead to different negative consequences, for example, to the lack of parts alignment, irregular gasket compression and as a result leaking of the product, misalignment of connected details, the origination of fastening details plastic deformations, and even breakage of bolts or pins. That is why controlling steel pins and bolts tightening force is very important for the provision of joint reliability and not only during assembly and installation of units and details of any other equipment but also during its operation. The present article is devoted to studying and testing of one of the modern and universal methods of bolt (pin) tightening force control—magnetic inspection based on structure-sensitive magnetic parameter control—remaining magnetic induction of the metal. The aim of present studies is to test the metal mechanical stress indicator IH-01m of a scanning type used at real facilities for measuring pin tightening force during operation.