Effect of Surface Defects and Internal Pressure on Fatigue Life of Coiled Tubing
- 10.2991/coal-18.2018.34How to use a DOI?
- coiled tubing, surface defects, internal pressure, fatigue life, local strain method
In the Complex service environment, the surface of coiled tubing has different degrees of defects, which can easily lead to the stress concentration on the surface of coiled tubing and cause premature fatigue failure of the tubing. In order to estimate the fatigue life of coiled tubing more accurately, and ensure the stability and safety of coiled tubing, it is necessary to consider the influence of surface defects on the fatigue life of coiled tubing. The fatigue test of QT800 coiled tubing is carried out under the condition of 0-7000psi internal pressure. The research shows that: (1) With the increase of internal pressure, the fatigue life of coiled tubing decreases significantly. When the internal pressure reaches 4000psi, the fatigue life of coiled tubing is reduced by about 80%.(2) The influence degree from large to small of surface defect on coiled tubing fatigue life is: circumferential defect, square pit defect and axial defect.(3) The fatigue life prediction model of coiled tubing with surface defects is obtained by local strain method, and the average error of theoretical value and experimental value is 8.85%, which can meet the requirements of engineering precision.
- © 2018, the Authors. Published by Atlantis Press.
- Open Access
- This is an open access article distributed under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Cite this article
TY - CONF AU - Bing Liu AU - Tao Li AU - Liping Xu AU - Baokun Han AU - Huitao Zhuang AU - Shulin Li PY - 2018/10 DA - 2018/10 TI - Effect of Surface Defects and Internal Pressure on Fatigue Life of Coiled Tubing BT - Proceedings of the 9th China-Russia Symposium "Coal in the 21st Century: Mining, Intelligent Equipment and Environment Protection" (COAL 2018) PB - Atlantis Press SP - 185 EP - 189 SN - 2352-5401 UR - https://doi.org/10.2991/coal-18.2018.34 DO - 10.2991/coal-18.2018.34 ID - Liu2018/10 ER -