Problem

A large Crude Oil Refinery uses a common Desalting process to remove salt & impurities from the oil prior to the refining process. This aggressive desalination process utilizes electrostatic coalescence to dissolve the salt. This process occurs in a welded tank which typically is coated to protect the weld seams from damage over a six-year scheduled maintenance cycle.

The customer was coating the tanks with a competitive product that failed well prior to the desired life cycle and schedule. As a result, the customer had damage to the tank weld seams. 

Process Conditions

• Temperature: 248° – 266°F (120° – 130°C)
• Pressure: 145 – 174 psi (10 – 12 bar)
• Electricity: 1,000 V/AC with changing polarity
• Life expectancy: 6 years
• Tank wall area: 1600 ft² (150 m²)

Solution

In 2015, the tank was taken out of service, the competitive product removed, sandblasted, and the weld seams repaired. The tank was then coated with 2 layers of Devcon® Brushable Ceramic Blue coating at 600 microns (0.6 mm) and returned to operations.

In 2021, at the end of the scheduled 6-year life cycle maintenance, the tank was inspected, and it was found that although the Brushable Ceramic had changed to a black color, the coating remained intact and providing protection to the tank & weld seams.

A full inspection revealed minor damage to the coatings, but these were in difficult to reach areas such as the manhole covers. The failures identified were far less than the customer’s target 10% failure rate thereby meeting their expectations. As a result,
they reapplied the Devcon Brushable Ceramic coating and returned the tank back to service.