Governmental regulations on natural gas transmission pipelines mandate that operators provide a baseline integrity assessments for their pipeline irrespective of the fact, whether these pipelines can be inspected from the inside by In-line inspection tools or not. In implementing their Integrity Management Programs and working towards the prescribed deadlines, operators are often confronted with challenging pipeline segments that are difficult to inspect with existing technology. A common challenge are installations or pipeline segments, with substantial changes in the internal bore.

Due to the inability of many currently available ILI tools to meet these challenging inspection requirements, some pipelines are still deemed unpiggable. Engineering and implementing the modifications necessary to make a pipeline piggable are often cost-prohibitive, since time-consuming and cumbersome integrity assessment methods have to be used to meet the regulatory requirements. In view of these technological difficulties and the prescribed time constraints, it is imperative that inspection solutions are found that are both economical and time-sensitive.

The paper discuss the development of a multidiameter inspection system utilizing magnetic flux leakage technology.  The inspection tool can operate in pipelines with a change in diameter in the range of 32” to 42”. Also an overview will be given about the design requirements for a multidiameter inspection tool fleet ranging from 10” to 48”. 

Developing such a complex tool requires rigorous testing. Accordingly, comprehensive tool testing took place at the ROSEN production site where a pipe was set up specifically to simulate the diameter changes and bends of the pipelines which were supposed to be inspected.