Cause Analysis of Round Thread Connection Dropout

Abstract:

Dropout may be happen to round thread connection by main reasons of design and process of product, material’s property, make-up torque or make-up position, field operation problems etc.. Casing’s property has get a high improvement with the development over the past decade in China. But the number of connection dropout accident didn’t declined obviously. These lead to great economy loss and safety hazard had taken place. Research on a round thread connection pullout case was carried out combining relative theorys with tests. Macroscopic analysis and dimension measurement and material’s physical and chemical properties were checked for casings and couplings. Thread inspection and full-scale tests were done for casing simples that are same lot with dropout. Comprehensive analysis was carried out on these results. The results showed that dropout failure was ascribe to two main causes. One is make-up location cann’t reach standard location at field end, and the other is incorrect holding position on coupling in the course of making up.

• Periodical: Advanced Materials Research (Volumes 479-481)
• Pages: 2028-2032
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.479-481.2028
• Online since: February 2012
• Authors: Zhi Yong Pan, Sheng Yin Song, Wen Hong Liu, Xin Li Han, Jun Han, Dan Zhang
• Keywords: Casing, Cause Analysis, Connection, Coupling, Dropout, Field End, Make-Up Position, Round Thread

References

[1] Wang Jiandong, Lin Kai, Zhao Kefeng, et al. Reliability and economical optimization of casing string used in Sulige gas field with low pressure and low permeability reservoirs [J]. Natural Gas Industry, 2007,27(12):74-76.

[2] American Petroleum Institute. Specification for casing and tubing [S]. Washington: API Spec 5CT, (2005)

[3] American Petroleum Institute. Specification for threading, gauging, and thread inspection of casing, tubing, and line pipe threads [S]. Washington: API Spec 5B, (2008)

[4] International Organization for Standardization. Petroleum and natural gas industries - procedures for testing casing and tubing connections [S]. Switzerland:ISO, (2002)

DOI: 10.3403/30025523u

[5] International Organization for Standardization. Petroleum and natural gas industries - equations and calculations for the properties of casing, tubing, drill pipe and line pipe used as casing or tubing [S]. Switzerland:ISO, (2007)

DOI: 10.3403/30175233u

[6] National Development and Reform Commission, People's Republic of China. Power tongs for petroleum drilling and servicing [S]. Beijing: SY/T 5074, (2004)