When a pipeline operator considers the concept of pipeline integrity, conventional wisdom has led operators to believe that evaluation techniques should only be concerned with processes or conditions that may have affected pipeline integrity during the construction or operation phases of a pipeline's lifecycle.

Due to unfortunate circumstances, pipeline incidents have become increasingly prevalent and the causation has not solely been attributed to these two factors. Non-homogeneous structural pipeline conditions created during the milling process have become an issue that pipeline operators must also consider when seeking to obtain a thorough evaluation of the integrity of their pipelines.

The focus of this paper is to discuss the milling condition and characteristics known as hard spots (localized hardening) incurred purposefully and inadvertently during the pipeline milling process, the detrimental conditions that may exist along with a pipeline exhibiting hard spots, and the current technology available to detect, characterize, and quantify hard spots within a pipeline system.

Subject
Sensors, Piping, Metal surfaces, Pipelines, Tools, Inspection, Stress cracking, Force, Metals, Steel, Hydrophobic interaction chromatography, Hydrogen, Hydrogen stress cracking
Keywords:
active field, residual field, low field, magnetic flux leakage (MFL), Hydrogen Induced Cracking (HIC), localized hardening, hard spots, residual stresses, hall effect sensors, coil sensors
© 2004 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2004
Association for Materials Protection and Performance (AMPP)
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