The Brief

To carry out a 5 yearly out of service tank inspection on a 12.19m diameter above ground tank to EEMUA 159 standards and to provide an inspection report to highlight any defects.

What We Proposed

An inspection that measured tank wall thickness using a remote access crawler and an internal scan of the floor using a Floormap scanner with STARS technology.

What We Delivered

A routine out-of-service inspection on an above ground storage tank. The previous inspection carried out by a different NDT company revealed only topside defects and consequently a lining was applied to the floor. Our Floormap 3Di showed topside AND bottomside defects on the first scan and subsequently, every following scan. A large number of floor plates showed areas with a combined loss ≥80%. As the topside of the floor was lined, an accurate perception of the topside pitting depth could not be determined. Due to the thickness of the applied lining, it was difficult to obtain an accurate manual ultrasonic thickness reading. Where it was possible to achieve a thickness measurement, a minimum reading of 1.90mm remaining on a nominal thickness of 6.35mm was noted (70% wall loss).

The client was informed about our findings and to check, as no underside corrosion had been reported in the past, had a section of the floor plate cut out. This confirmed our results and reinforced the reliability of our inspection techniques and the experience of our technicians.