Selection of Field Applied Liquid Rehabilitation Pipeline Coatings

There are over five dozen field applied liquid rehabilitation pipeline coatings in the US market with limited performance data available from suppliers. Although there are many test methods in the literature for evaluation of pipe coatings, there are no commonly accepted test protocol and acceptance criteria for selecting coatings. End users have great difficulty in selecting appropriate coatings to protect their buried pipelines. Also, no convincing technical data can be obtained from suppliers to help us determine the upper service temperature for a coating. Some coatings have long dry-to-touch time and attract insects that crawl over the wet paints at night to produce holidays which require repairing the next day. The purpose of this work is to develop a test protocol considering both application convenience and good performance and to select the coatings to rehabilitate our pipelines. The attributes for application convenience are environmental friendliness, pot life, dry-to-touch time, backfill time, etc. The coating performance includes cathodic disbondment, penetration, impact, and abrasion resistance. The acceptance criteria have also been developed to make the selection. Test methods to determine upper service temperature for the coatings were also developed. This test protocol uses standard ASTM test methods with slight modifications and can be used by both coating suppliers and end users.