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Non-destructive Testing of Cement Plant Mills, Gears, and Kilns

Updated: Jan 14, 2022

Cement plants are large scale operations that require large scale machines to produce the materials required to build a wide variety of structures. The non-destructive testing requirements of a cement plant are very unique and required a broad range of NDT testing methods to assess reliably the critical plant infrastructure. Important cement plant machines and components that require non-destructive testing include cement ball mills, pinion gears, kilns and bull gears. NDT methods relevant to cement plants include visual testing (VT), magnetic particle testing (MT), eddy-current testing (ET), ultrasonic thickness testing (UTT), phased array ultrasonic testing (PAUT), and liquid penetrant testing (PT). This article presents some examples of cement plant mill, gear, and kiln non-destructive testing applications.

Description of Cement Plant Machinery

Figure 1: Cement plan ball mill non-destructive testing is performed with a variety of different methods for cracks.

Cement plant machinery and processes are supported by unique and critical infrastructure including ball mills, a variety of gears, kilns, and conveyor components. Ball mills are large very large cylinders made from structural steel that include multiple full penetration girth and seam welds. Over a finishing mill’s lifetime, it is subjected to millions of cycles of fatigue and complex stress loading. Thermal stress cycling is also relevant give the high temperatures at which the mill operates. While the shall of the finishing mill is very thick, fatigue crack do initiate and propagate along the axial and girth weld toes, roots, and subsurface. Cement plant finishing mill NDT uses magnetic particle testing, ultrasonic testing, eddy current testing, and in some cases alternating current field measurement (ACFM) testing.

Figure 2: Cement plan ball mill pinion gear non-destructive testing is performed with a variety of different methods for cracks.

Pinion and bull gears used to drive the mills and other machinery operate at an intense level based on demand. Gear surfaces become embrittled and eventually chip resulting in material loss or form cracks that case gear tooth failure which may require downtime and replacement. Cement mill gear NDT uses magnetic particle testing, eddy current testing, alternating current field measurement (ACFM) testing and in some cases liquid penetrant testing depending on the size of the gear.