The paper compares various types of exterior repair methods for repairing high-pressure gas pipelines and oil- / product pipelines that are currently available on the market and used in the field and that have been subjected to varying degrees of field testing.
The paper draws on the results of the DGMK report 2016 which refers to the DGMK report from 1994 while also reassessing them in light of the current state of the art.
In addition, repair methods such as carbon-fiber-reinforced repair methods that had not been included in the 1994 study are described; test results are presented; advantages and disadvantages are shown; and the repair methods are assessed regarding their suitability to repair defects.
The analysis of the methods described in the literature showed that neither the procedures nor the test criteria to qualify repair methods are uniform or mutually comparable. The same is true for the type and scope of the tests conducted to assess repaired defects.
The applicability and efficacy of the various types of exterior repairs will be examined with an eye to potential defect types.
In a summarizing chart, the various described repair methods will be presented and rated according to their applicability to various types of defects.
An in-depth observation of the effects and the stress conditions inside the pipe walls, combined with an assessment of general applicability, showed that repair methods using sleeves without welding on the pressure-bearing pipeline, as well as repair methods using carbon-fiber-reinforced bandages, demonstrate the greatest advantages regarding safety and operational availability. Therefore the DGMK report 2016, prepared by TÜV SÜD IS, recommends prioritizing these repair methods.