Proceedings of the 9th China-Russia Symposium "Coal in the 21st Century: Mining, Intelligent Equipment and Environment Protection" (COAL 2018)

Effect of Surface Defects and Internal Pressure on Fatigue Life of Coiled Tubing

Authors
Bing Liu, Tao Li, Liping Xu, Baokun Han, Huitao Zhuang, Shulin Li
Corresponding Author
Bing Liu
Available Online October 2018.
DOI
https://doi.org/10.2991/coal-18.2018.34How to use a DOI?
Keywords
coiled tubing, surface defects, internal pressure, fatigue life, local strain method
Abstract

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.

Copyright
© 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/).

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Volume Title
Proceedings of the 9th China-Russia Symposium "Coal in the 21st Century: Mining, Intelligent Equipment and Environment Protection" (COAL 2018)
Series
Advances in Engineering Research
Publication Date
October 2018
ISBN
978-94-6252-570-2
ISSN
2352-5401
DOI
https://doi.org/10.2991/coal-18.2018.34How to use a DOI?
Copyright
© 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  - https://doi.org/10.2991/coal-18.2018.34
ID  - Liu2018/10
ER  -