The Caliper pig provides a powerful tool and secondary inspection to the Intelligent Pigging. A caliper tool continuously measures the inside diameter of the pipeline through an array of sensing fingers that are spring loaded to hold them in contact with the pipe wall. As the tool moves through a pipeline all radial sensor movements are detected and recorded. Odometer wheels generate distance data which is continuously collected and stored with the measuring data from the radial sensing fingers.
Any variation to the internal surface of the pipe is registered in a user friendly format that serves to independently verify any ID features.
Caliper tools utilize a set of mechanical fingers or arms that ride against the internal surface of the pipe. Caliper pigs are used to measure pipeline internal geometry. They have an array of levers mounted on the body of the pig. The levers are connected to a recording device in the pig body. The body is normally compact, about 60% of the internal pipe diameter, which, combined with flexible cups, allows the pig to pass constrictions up to 30% of the bore. The ability of a caliper pig to pass constrictions means minimal risk of becoming stuck.
The Caliper tool can be combined with a Geometry pig, which incorporates an Internal Navigation System (INS) that enables 3D software representation of the pipe run, showing deformations, misalignments, bends, elevation changes and directional changes to the pipe. They can also generally detect and locate main-line valves, fittings, and other appurtenances. As with all in-line inspection tools, these tools have limits on their use and in the extent of results obtained which need to be assessed on a case by case basis.
Dacon's software is easy to use and allows for full documentation of the entire pipe location in an easy to read format.