All ETDs from UAB


Lindsey McCall

Advisory Committee Chair

Robin Foley

Advisory Committee Members

Viola L Acoff

Roy Koomullil

Charles Monroe

Selvum Pillay

Document Type


Date of Award


Degree Name by School

Doctor of Philosophy (PhD) School of Engineering


Oil and natural gas touch the lives of most people around the world each day in one way or another. As the demand for these products has risen, so has the need for more pipelines. The pipelines that transport oil and natural gas must meet a strict set of criteria to ensure safety. These criteria include mechanical properties and nondestructive testing requirements. The purpose of this study was to determine how to correlate welding inputs and outputs to weld quality, specifically the occurrence of welding discontinuities that are detrimental to the pipe and mechanical properties. The three conclusions of this study were as follows: 1. A threshold outer diameter (OD) squeezeout exists above which the probability of weld defects decreases. 2. A relationship between the OD squeezeout and mill inputs exists. 3. The process of high frequency electric resistance welding is robust enough to accept a + 12% change in “V” length, twice the distance from the weld contacts to the apex, with no significant change in mechanical properties. These objectives were reached by correlating measurements taken from untrimmed weld samples to mill operating inputs, percentage of welding defects, and mechanical properties. The ultrasonic rejection rate dropped greatly for OD squeezeouts greater than 0.05”. As the heat input increased, the heat affected zone width increased while the OD squeezeout decreased. Also, all the mechanical properties of pipe produced when the “V” length was adjusted by ¬+12% met the standards set by the American Petroleum Institute (API).

Included in

Engineering Commons



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