Robotics for Internal In-Service Inspection of Aboveground Storage Tanks

Introduction

The conventional approach for tank floor inspection involves taking equipment out of service and performing a Confined Space Entry (CSE). CSE includes de-inventorying, fluid transfer, cleaning, hazardous waste disposal, and many other activities, some which may be hazardous. This approach can take months to complete for large tanks. Asset owners may incur high costs and potential revenue losses from unavailable tanks in critical production service. 

Robotic inspection tools and application procedures are available for implementation in and around potentially explosive atmospheres. Often tanks need not be de-inventoried or cleaned for in-service inspection using robotic tools. This type of robot can be inserted through a deployment assembly attached to a manway on the tank roof (Figure 1). Most robots are remotely controlled and connected by an electrical umbilical cord back to a control module (Figure 2). The robot is lowered into the tank and propelled along the tank bottom.

The types of hazardous fluid tanks that are inspected with in-service robots now include crude oil, jet fuel, kerosene, diesel, lube oil, gasoline, other hydrocarbon distillates, and chemicals. The technology provides a method that in some cases can meet tank floor coverage requirements in API 653 [1].