This paper discusses two common problems, “weld tenting” and low coating thickness over the external weld, and their causes in traditional three layer polyolefin pipeline coatings. To tackle these problems, a new approach to applying multilayer polyolefin coating to pipes is introduced. The new system consists of side-extruding high density polyethylene over a graded structure polyethylene (GSPE) coating. This study demonstrates that the new coating approach can provide exceptionally uniform coverage of external welds, successfully eliminate “weld tenting”, and significantly reduce residual stresses in the coatings.

Subject
Thermoplastic coatings, Seams, Coating performance, Coatings, Piping, Adhesives, Rocks, Extrusion, Fusion bonded epoxy coating, Weld seams, Polyolefins, High density polyethylene, Three-layer polyethylene coating
Keywords:
multi-layer polyolefin coatings, weld geometry, fusion bonded epoxy, polyolefin, cooling method, weld tenting
© 2007 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).
2007
Association for Materials Protection and Performance (AMPP)
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