Pipeline transport in order to avoid melting the frozen ground by hot petroleum which would result in sinking the pipeline in the ground. Maintenance of pipelines includes checking cathodic protection levels for the proper range, surveillance for construction, erosion, or leaks by foot, land vehicle, boat, or air, and running cleaning pigs, when there is anything carried in the pipeline that is corrosive. US pipeline maintenance rules are covered in Code of Federal Regulations(CFR) sections, 49 CFR 192 for natural gas pipelines, and 49 CFR 195 for petroleum liquid pipelines. In the US, onshore and offshore pipelines used to transport oil and
Central Asia–Center gas pipeline system proposed to renovate existing systems and construct a new parallel pipeline to the western branch. On 12 May 2007, Vladimir Putin of Russia, Nursultan Nazarbayev of Kazakhstan and Gurbanguly Berdimuhamedow of Turkmenistan signed a memorandum for renovation and expansion of the western branch of the pipeline. On 20 December 2007, Russia, Turkmenistan and Kazakhstan finalized agreement on construction of the Caspian Coastal Pipeline parallel to the existing CAC-3 pipeline (known as Bekdash–Europe pipeline or Okarem–Beineu pipeline). Almost all Uzbek and Turkmen natural gas is delivered through the CAC pipeline system, mainly through the eastern branch due to location of production