T.D. Williamson, Inc. has announced the successful development of a new 48-inch Gas Magnetic Flux Leakage (GMFL) inspection tool, recently engineered at the TDW facility in Salt Lake City.
The new tool, which has already had a field run on a 48-inch natural gas transmission line in Canada, reveals the versatility of the services that TDW offers to its pipeline customers. TDW can provide cleaning pigs and inline inspection (ILI) services using its 48-inch Kaliper®360 tool for identifying physical anomalies and geometry in a pipeline and using its 48-inch GMFL tool for identifying corrosion features and pipe wall loss. TDW can also offer hot tapping and plugging services to assist with the repair of identified anomalies.
GMFL Tool: consistent velocities offer more accurate inspection
The new tool enhances TDW’s ability to offer a full range of inspection services to its clients. “This is a first,” said David Soanes, Account Manager for TDW in southwestern Ontario. “Never before have we been able to offer 48-inch high pressure, natural gas transmission inline inspection. We are delighted by our ability to offer our clients a range of services catered specifically to their pipelines. Likewise, our clients are pleased to be able to have all of their needs handled by one supplier,” he added.
TDW’s Gas MFL (GMFL) tool is uniquely designed to fill a niche in the ILI market. Gas pipeline MFL tools do not enjoy the advantages that liquid product MFL tools do. In a liquid line, the product (for instance, crude oil) provides lubrication, reducing friction between the inspection tool and pipe wall. This makes it possible to maintain a steady speed as the MFL tool traverses the pipe. In a gas environment, however, opposite conditions predominate: without the lubrication, friction rises, causing the magnetic inspection tool to “stick” to the pipe wall. In addition, it is difficult to maintain a steady tool speed because variations in gas pressure cause the tool to stall and surge as it moves within the line.
The TDW high resolution GMFL tool addresses these impediments with three strategies. First, each magnetizer “floats” individually so that magnetic forces are consistent whether in a thick or thin wall, or a tight bend. By reducing tool drag, floating magnetizers enable more consistent velocities. Second, the traditional MFL tool has coarse steel brushes that magnetize the pipe wall (so that sensors can read magnetic loss levels). These are replaced in a GMFL tool with smooth, flat wear skid plates that glide more easily. Finally, the tool’s design allows for as much as 25% bore reduction and is constructed of lighter weight materials, making the TDW GMFL tool approximately half the weight of other 48-inch tools. All this means that the GMFL tool offers a greater ability to negotiate breadth reductions which, along with reduced tool drag, allows for more consistent velocities and, therefore, more accurate inspection.
An additional feature of TDW’s ILI services is the ability to remove foreign liquid from a gas pipeline. Over time, liquid (for instance, glycol) is sometimes introduced into the line and is not adequately removed. This then collects in pools of liquid at low levels. These pools reduce the throughput of the line to below its optimum capacity, rather like a blockage in the drain of a sink. TDW’s Pigging Products Division (PPD) has addressed this problem by providing custom engineered cleaning pigs with special urethane cups and discs designed to “shoot out” liquid settled in the pipe.
Busy times ahead for TDW’s new GMFL tool
The 48-inch GMFL tool is the largest ever developed by TDW; previously, the maximum size offered was 42 inches. “The interest already shown in this tool indicates that there was a significant gap in the ILI market that we have been able to fill,” said Soanes. “We are certain that there are busy times ahead for our new 48-inch GMFL tool,” he added.