During the last thirty years a bundle of accidents in large size tank beds for carbon storage was fixed. In spite of it there is not any existed method for effective detection of faults and cracks in filled up tank beds.

In this article a variety of emergency situations with tank beds for oil products storage was analyzed and new technical decisions were suggested. These decisions are based on usage of devices of nondestructive testing for localization of fatigue cracks in the circumference weld of large size tanks and organization of monitoring of deflected mode of an object by way of finding moment of cracks formation.

The devices applied in this method are ultra-sonic thickness gauge and highly sensitive magnetoelastic sensor. The last one was developed by author. This cracks determination method practically allows to find out cracks and defects of I, II and III type. It also allows to decrease financial, temporal and technological investments for investigation of tank beds for oil products storage without oil products removal and completely prevent emergency situations.