Avoiding leaks in floating roof tanks

We experienced a leak occurring from roof leg pin hole location. Tankage floating roof is designed with single deck roof with side and center pantoon system.

Leak observed from the above location at two different cases and different conditions:

1.During the peak summer when ambient temperature started increasing, leak started observing from the pin hole location. Observed on the crude Tanks and slop Tanks.

2. During rain, water found accumulated Tank single deck roof. Due to bulging of roof plate, the elevation towards the roof drain is disturbed and water getting accumulated on roof. Due to water accumulation weight on water accumulated part raised result in slight lowering of roof. Lowering of roof result into roof leg pin hole leak occurrence. 

We look forward to receive suggestions and/or solutions that help avoiding such leaks occurring in the future.