68m Diameter Storage Tank roof with 65 locations of severe external & pitting corrosion leading to numerous through-wall defects.

 

The aim of PCR composite repair is to restore the integrity to the tank roof upper skin plates using a patch repair process. The defect sizes were varying through-wall penetrations of 10 - 250mm diameter extending up to 3000mm in length in varying locations.  

 

Challenges:     

• Application during summer months with high ambient air temperature conditions.     

• Bespoke adhesive required to cope with thermal movement of the tank.     

• Due to spark risks, the surface preparation is limited to ST-3.  

 

Actions:     

• Pre-Cured Patch plates were manufactured using the PCR-GX (Glass Fibre Reinforced Plastic) composite repair system and machine cut to size. Plate thickness:  5mm.     

• PCT utilised non-spark power tools to obtain an ST-3 surface preparation on the tank roof over the corroded areas.     

• PCT epoxy adhesive layer applied to provide flexible bonding between steel and FRP plates in order to compensate with tank roof thermal expansion and movement.     

• The PCR-GX patch plates were applied to the 65 locations and compression applied until the epoxy adhesive fully cured.