All ETDs from UAB

Authors

Lindsey McCall

Advisory Committee Chair

Robin Foley

Advisory Committee Members

Viola L Acoff

Roy Koomullil

Charles Monroe

Selvum Pillay

Document Type

Dissertation

Date of Award

2020

Degree Name by School

Doctor of Philosophy (PhD) School of Engineering

Abstract

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

Share

COinS
 
 

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.