The inspection of pipelines that contain epoxy, HDPE or cement mortar liners is impossible with conventional MFL and UT pigs. Internal HDPE liners have been an effective means of internally protecting carbon steel pipelines. The potential threat of external corrosion (for example as a result of 3rd party damage or internal corrosion still warrantable periodic inspection of lined pipe - especially given the nature of the products typically transported in lined pipes. The relatively heavy thickness of HDPE liners and the requirement to prevent damage to the liner, limit the effective deployment of traditional inspection technologies. Remote Field Testing (RFT) technology is a through- transmission technique and therefore relatively lift-off insensitive. It is well suited to inspect steel pipelines through thick HDPE liners. The original development of RFT pipe inspection tools has been mostly driven by the municipal water environment, where metallic water mains can exhibit heavy internal scaling. For the inspection of lined oil and gas pipelines, a custom RFT tool was developed to accommodate the requirements imposed by lined oil and gas pipes. The developed RFT in-line inspection tool has been successfully deployed in HDPE lined pipe since 2008. Repeat inspections of a lined pipeline in 2008 and 2010 showed that RFT data has excellent reproducibility, with only a few minor deviations observed in the 2010 data compared to the 2008 baseline. Subsequent verification digs successfully correlated RFT signal deviations in the 2010 data to localized corrosion ranging up to 18% in depth The field Inspections showed RFT to be a very promising inspection technique and highlighted the technique's ability to detect stresses inside the pipe wall due to soil loading.
Inspection of lined pipelines with in-line inspection tools
Prüfung von ausgekleideten Pipelines mittels In-Line-Prüfwerkzeug
CINDE Journal (Canada's National NDT Magazine) ; 32 , 6 ; 9-12
2011
4 Seiten, 4 Bilder, 6 Quellen
Article (Journal)
English
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