This paper describes the high-resolution in-line inspection of several ethylene pipelines in a network in the south of France. The pipelines inspected have diameters ranging from 6” to 10”. Sectional lengths up to approx. 100km were inspected in a single run. A number of challenges were posed by the actual configuration of the pipelines and operational constraints of the pipeline operator. For various reasons the inspections were done in nitrogen.
The ILI challenges included: small diameter lines combined with rather long sections and presence of a number of ID restrictions. Magnets and other tool parts remained in the pipelines from a previous unsuccessful attempt to achieve a first ILI in the lines. This debris had to be recovered before the inspection runs could be done. Pigging in a gaseous medium meant that substantial speed excursions had to be mitigated.
The ILI campaign included high-resolution GEO, MFL/DMR and XYZ mapping. In addition to that due to the presence of significant amount metallic dust and lost tool parts in some of the line sections, a special pre-inspection cleaning program was part of the scope of work. For the purpose of the XYZ mapping and tool tracking a very extensive marking program was developed and performed.
To maintain and control the necessary nitrogen pressure and flow a special pigging method developed as part of the project execution.
A joint development project is described in which 3P Services and Total Raffinage, France defined a method to perform the tool runs and for 3P to prepare tools with the necessary characteristics. The lines were first inspected in 2013 and then re-inspected in 2018.