Pipeline and storage tank inspection using robots

Natural gas and oil pipelines are proliferating all over the United States. According to the federal government, more than 2.6 million miles of pipelines supply the nation’s energy needs. Data from the Pipeline and Hazardous Materials Safety Administration shows an average of 200 crude oil spills a year are reported, totalling 8.9 million gallons.

California has one of the most enlightened and environmentally-conscious set of guidelines and controls for the safe operation of pipelines in the United States. A previous article in this column highlighted relatively recent spills on the Santa Barbara county beaches.

‘Pigging’ has been used for many years to clean large-diameter pipelines in the oil industry. Today, however, the use of smaller-diameter pigging systems is increasing in many continuous and batch process plants as plant operators search for increased efficiency and reduced costs.

The original ‘pigs’ were made from straw, wrapped in wire and used for cleaning. They made a squealing noise when travelling through the pipe, sounding to some like a pig squealing. Well, that’s one possible reason for the term. Another would be that it is an acronym of the term ‘pipeline inspection gauge’ or ‘pipeline intervention gauge’.

Pigs are also used in oil and gas pipelines to clean the pipes. There are also ‘smart pigs’ used to inspect pipelines for the purpose of preventing leaks, which can be explosive and dangerous to the environment. Usually, they do not interrupt production, though some product can be lost when the pig is extracted. They can also be used to separate different products in a multi-product pipeline.

If the pipeline contains butterfly valves, or reduced port ball valves, the pipeline cannot be pigged. Full-port (or full-bore) ball valves cause no problems because the inside diameter of the ball opening is the same as that of the pipe. There is continued research into the inspection of non-piggable pipes. A new product coming to the market promises to add additional processes for evaluating the condition of the pipeline. Diakont, an international high-tech engineering and manufacturing company, headquartered in San Diego, California, has developed a robot that can obtain real-time condition data about the entire volume of the pipeline. It is called the Remotely Operated Inspection System, or ROTIS, and it crawls through the pipeline using a remotely-controlled set of wheels, which permit it to bypass bumps, bends and internal unevenness. It has a system of ultrasonic sensors, which provide accurate determination of wall thickness, lasers and video to record damage and defects. A control station is mounted in a truck and connects to the robot for receiving and processing data. A typical inspection covers about one quarter of a mile in a working day.

Diakont recently developed a device called the Stingray, which works on the same principle and can be placed in above-ground storage tanks without removing the flammable sludge to provide data about the condition of the inner floor and shell of the tank. This excludes the requirement to clean the tank and make it safe for wokers to enter in order to obtain the same condition information. Several other companies are providing inspection tools for tanks that do not require extensive cleaning or human entry.

Diakont is in the process of obtaining regulatory certification for the Stingray and its launch is scheduled for the autumn of this year. Stay tuned for more information about the success evaluation of these tools.

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