Background

A sour water tank required a closed-loop tank cleaning methodology due to extremely high H2S content. Additionally, the tank contained an estimate 4 feet of sludge and solids deposits.

Challenge

The tank presented a significant H2S (sour) hazard, with on-site sampling performed by RJ Maclean confirming 180,000 ppm in the vapor space. The presence of iron sulfides within the tank presented an additional pyrophoric hazard. The tank sludge needed to be neutralized for safe transportation and disposal.

Solution

RJ Maclean presented a chemistry solution to effectively neutralize the H2S hazard without the risk of any personnel exposure. Comprehensive product sampling and analysis was performed to ensure the sludge was effectively treated and safe for transport and disposal. Following the SandPiper circulation and product drawdown, RJ Maclean proposed utilizing robotic cannons to complete tank degassing for safe entry and detailed cleaning.

Result

The H2S hazard was neutralized with tank circulation, vapor phase degassing and manway cannon washing. The tank cleaning scope was completed with a 45 percent reduction in personnel entry, and without any personnel exposure to hazardous atmosphere. Thanks to thorough and complete mixing, a 35 percent reduction in disposal volume was achieved. The effectiveness of cleaning chemistry and robotics led to a 30 percent reduction in project personnel cost.