A New Design Method for Anchor Blocks of Gas Transmission Pipelines

Document Type : Research Article


1 Golder Associates Ltd, Montreal, Canada

2 Iranian Gas Engineering and Development Company


Natural gas transmission pipelines transport the natural gas at elevated temperatures and high internal pressures. The pipelines will expand when they are put into operation under the influence of increased internal pressure and temperature. The movement due to such expansion is significant for large diameter pipelines which operate at high pressure and elevated temperature. The pipeline needs to be restrained near compressor stations in order to prevent the transmission of such movement to equipment and facilities within the station. Concrete anchor blocks are commonly used to restrain the movement of buried pipelines on both sides of compressor stations. Anchor blocks for transmission pipelines are usually massive because of the high axial stress in the pipe which results in large thrust force. Current design procedures are usually based on providing an adequate margin of safety against block sliding, block overturning, and soil bearing pressure. This paper presents the results of an analytical study on the response of soil, pipeline, and anchor block at different operating pressure and temperatures. Nonlinear finite element analyses which include modeling of soil-pipe and soil-block interactions are carried out to evaluate the design procedures. The results indicate that the concept used in the current design procedures is fundamentally flawed because it is based on controlling forces rather than displacements. Based on the results of these analyses, a more rational design procedure that is based on controlling the displacements is introduced. The proposed design procedure results in a substantial reduction of the size of anchor blocks.


Main Subjects

[1] Peng, L. C. “Stress analysis methods for underground pipelines”, Pipe Line Industry, 47(5), pp.65-74, (1978).
[2] Duncan, J. M., & Mokwa, R. L. “Passive earth pressures: theories and tests”, Journal of Geotechnical and Geoenvironmental Engineering, 127(3), pp.248-257, (2001).
[3] Irsyam, M., Gantina, R., Valianti, M., & Himawan, A. “Remedial action for the movement of buried gas pipe and anchor block on a very soft soil due to fill embankment”,  J. Indonesian Oil Gas Community, 10(1), pp.13-14, (2007).  
[4] Al-Gahtani, H. J. “Optimum design of buried pipeline block anchors”, Practice Periodical on Structural Design and Construction, 14(4), pp.190-193, (2009).
[5] Gupta, C., Imran H. “Thrust Block for Pipelines - Case Study of Water Supply Scheme for a Town Berinag”, International Journal of Research in Advent Technology, 6(7), pp.1587-1592, (2018).
[6] Zhang, L., Yan, X., & Yang, X. “Using the unit force method to analyze thrust acting on anchor blocks caused by thermal expansion displacement of X80 tunnel pipelines”, Journal of Pipeline Systems Engineering and Practice, 7(1), p.04015012, (2015).
[7] Yan, Y., Zhang, L., & Yan, X. “Push Force Analysis of Anchor Block of the Oil and Gas Pipeline in a Single-Slope Tunnel Based on the Energy Balance Method”, PloS one, 11(3), p0150964, (2016).
[8] Rahman, M. K., Abu Ghdaib, A. K., Ahmed, A., Shaahid, S. M., & Rehman, S. “Field monitoring of an in-service thrust anchor block and pipeline”, 1st Middle East Conf. on Smart Monitoring, Assessment and Rehabilitation of Civil Structures, International Society for Structural Health Monitoring of Intelligent Infrastructure (ISHMII), pp. 1-10, (2011).
[9] Rankine, W. “On the stability of loose earth”, Philosophical Transactions of the Royal Society of London, Vol. 147, (1857).
[10] National Iranian Gas Company, “Iranian Gas Standard IGS-C-PL-100(1)”, (2011), (in Persian)
[11] ALA (American Lifelines Alliance). “Guidelines for the design of buried steel pipe”, Reston, VA. (2001).
[12] Iranian Ministry of Petroleum “Iranian Seismic Design Code for Petroleum Facilities and Structures” Code no. 038, 3rd Edition (2016).
[13] Wijewickreme, D., Karimian, H., & Honegger, D. “Response of buried steel pipelines subjected to relative axial soil movement”, Canadian Geotechnical Journal, 46(7), pp.735-752, (2009).
[14] Das, B. M. “Principles of foundation engineering”, Cengage learning, (2015).
[15] Fang, H. Y. “Foundation engineering handbook”, Springer Science & Business Media, (2013).
[16] Vasseghi A. “Final research report on optimum design of anchor blocks”, Iranian Gas Engineering and Development Company, (2013), (in Persian)