How to Safely Inspect Petrochemical Pressure Vessels Internally

Collect visual data from inside petrochemical plant pressure vessel featuring complex geometry

Standard Magg™ miniature magnetic crawler

The solution may seem obvious: send in a robot to carry out the inspection job. A proven alternative, unmanned inspections enable successful condition monitoring and turnaround planning. An unmanned ground vehicle will look for any damage that can make the pressure vessel unsafe for operation like cracks, corrosion, or weld defects. The Magg™ is a miniature magnetic crawler well known by the petrochemical industry. The confined space entry robot was even featured as the safer inspection solution in Dow’s sustainability report. Offering real-time recording of live video, still images, and sensor data during structural integrity assessments, operators deploying Magg can safely collect auditable information for informed decisions.

Unfortunately, for this specific application, the polyethylene pressure vessel presented a few challenges. Unlike a typical storage tank, these pressure vessels exhibit more complex geometry forcing a remotely operated crawler to climb vertical walls but also incline planes and transition sections without falling off or losing traction. Moreover, the surface of this pressure vessel had a build-up of non-magnetic, slippery material.

Inspection robot customized to overcome slippery surface and difficult angles

Modified Magg™ miniature magnetic crawler

Sometimes even the best can benefit from a helping hand. In this case, Eddyfi Technologies resolved the problem with two arms. By exploiting the modular design of the Magg and building from previous experience, we were able to design new magnetic arms that extend out in front of the vehicle. Resembling the inspection crawler’s own roller skates, these new “reactor arms” were bolted onto the tracks that drive the Magg. The remotely operated vehicle was extensively tested in the factory to confirm its ability to negotiate a transition mimicking the shape of the reactor vessel, even with a simulated 6.35-millimeter, or 0.25-inch, thick coating. The custom robot solution successfully enabled the risk assessment of critical factors such as design, cyclic fatigue, and product induced corrosion, as well as locating suspect areas internally for additional analysis – all while removing the need for stopping service, cleaning or emptying vessels, or requirement for scaffolding.