Most deep oil wells have temperatures as high as 135°C at the wellhead. This oil is transported from the well to the manifold and distribution area. One of the most critical properties of the external organic coating is its resistance to high temperature. It has been found that most of the organic coatings have had problems at temperatures higher than 80°C. Furthermore, the cathodic protection applied to high temperature pipelines will affect the performance of the coating when it has some defects. There are many pipelines in Venezuela that operate at temperatures in the range between 135°C and 80°C. An intensive laboratory study has been carried out to find the best coating that lasts longer in these environments.

The laboratory tests were oriented to age the system at 135°C in a convection oven under soil conditions simulating those where the pipelines are installed. A study on the effect of cathodic protection at -1.5 V (vs. Cu/CuSO4) at different temperatures (25, 65 and 95°C) was carried out. Also, keeping the temperature constant at 95°C the potential was varied from -0.8 to -3.0V. The effect of the chlorine, coming from the electrolyte, on the properties of the coating during the cathodic disbonding test was also studied.

The results indicate that most of the coatings evaluated failed the aging test at 135°C. Only the irradiated polyethylene kept its properties. On the other hand, the fusion bonded epoxy presented good behavior at 95°C when the applied potential was lower than -1.5 V (vs. Cu/CuSO4), while the rest of the coating systems presented high cathodic disbonding.

Subject
Primers, Coatings, Tape, Pipelines, Fusion bonded epoxy coating, Fiber reinforced plastic, Cathodic disbondment, Polyolefins, Hardness, Soil, Impact resistance, Coating systems, High temperature
Keywords:
Coating, high temperature, external corrosion, thermal stability, cathodic protection
© 1995 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).
1995
Association for Materials Protection and Performance (AMPP)
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