Failure Analysis of a High Pressure Butt-Weld Flange

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Published: Jun 22, 2016

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F. Ahmed
F. Hasan
L. Ali

Abstract

This paper constitutes the failure analysis of a 24-inch diameter ‘Flange’ that had been welded to a high-pressure gas transmission pipeline. The flange had ruptured catastrophically during the hydrostatic test that was conducted to testify the integrity of the flange as well as that of the weld joint. The rupture had occurred along the weld through the heat-affected-zone (HAZ) on the flange side. The flange, which was a steel forging (of Class 600 as per ANSI Standards) made from ~ 0.25 % carbon steel, was expected to exhibit good weldability. However, the metallographic examination revealed that the steel had a coarse grain-size and an in-homogenous microstructure wherein pearlite-rich regions, ~2-3 mm across in size, were sporadically distributed in the microstructure. The coarse grain-size coupled with the presence of pearlite-rich patches in the microstructure had locally reduced the weldability of the steel, i.e., increased its tendency towards HAZ cracking during welding.

Article Details

Issue
2008: Volume 3 July 2008
Section
Polymer Engineering and Chemical Engineering, Materials Engineering, Physics, Chemistry, Mathematics

References

Hafeez I., Kamal M. A, Ali G. “Assessment of Resistance to Rutting of Asphaltic Materials using a Wheel Tracker”, Journal of Engineering and applied Sciences, N.W.F.P University of Engineering and Technology Peshawar, Vol. 28, No. 2, pp 53-60, ISSN 1023-862X, July-December 2009.

Ludomir Uzarowski. “The development of asphalt mix creep parameters and finite element modeling of asphalt rutting” Dissertation, 2006, University of Waterloo, Ontario, Canada.

Stumpf, W., Van Rooyen, G.T. Mechanical Metallurgy NMM 700, Course notes, University of Pretoria, Pretoria, 2007.

Asphalt Institute. “Superpave TM Mix Design” Superpave Series SP-2, 1996, Lexington, Kentucky, USA.

Hofstra, A. and A. J. G. Klomp. Permanent Deformation of flexible pavements Under Simulated Road Traffic Conditions. Proc., 3rd International Conference on the Structural Design of Asphalt Pavements, University of Michigan, 1972, pp. 613-621.

M.A. Kamal, M.J.M. Niazi. Effects on Rutting & Stiffness by Varying course and Fine Aggregate. Proceedings of the international conference on advance characterization of pavement and soil engg materials, Athens, Greece.2007, pp 1285-96.

Andrain Riccardo Archilla and Samer Madanat. Development of a pavement rutting model from experimental data, Journal of Transportation Engineering, 2000, pp291-299.

National Highway Authority, Pakistan, “Surface courses” Item No. 305-1, NHA General Specifications, 1998.

Asphalt Institute. Mix Design Method. Manual Series No. 2 (MS-2), 6th Edition, 2003, P55-78.

K.B. De Vos. and AJ. Feeley. Universal Testing Machine, Hardware Reference, UTM-5P, 2002.

European Standard: prEN 12697-22. “Test methods for hot mix asphalt” part-22, wheel tracking. U.K, 2002.