| Titre : |
Polyurethane pipeline coatings : Do changes in appearance indicate changes in performance ? |
| Type de document : |
texte imprimé |
| Auteurs : |
Stuart G. Croll, Auteur ; Chunju Gu, Auteur ; Vinod Upadhyay, Auteur ; Brent D. Keil, Auteur |
| Année de publication : |
2017 |
| Article en page(s) : |
p. 30-42 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Composés aromatiques
Essais accélérés (technologie)
Pipelines -- Revêtements protecteurs
Polyuréthanes
Revêtements protecteurs -- Détérioration
Spectroscopie d'impédance électrochimique
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
Seel water pipelines are intended to be in service for many decades and are protected against corrosion from ground water by cathodic protection and by thick organic polymer coatings. The most common protective coating is a single, thick (> 0.75 mm) layer of an aromatic polyurethane. These coatings are 100-percent solids, two-component spray-applied coatings that cure in less than 30 seconds under normal ambient conditions. Other types of coatings are sometimes used but do not provide the same balance of performance and economy. Occasionally, coated sections of a pipeline may be stored aboveground for an extended period prior to burial and, depending on the local climate, these aromatic polyurethanes rapidly and obviously lose gloss and change color. Inevitably, the substantial changes in appearance cause questions about the corrosion protective abilities of the coating.
Upon oxidation, gloss is diminished considerably by the increase in surface roughness that occurs as a coating polymer is randomly eroded. Aromatic polyurethane polymers also become yellow and occasionally a pigment will be bleached by sunlight. After extended oxidation, coatings may chalk with a surface that has become degraded to the extent that it is powdery and almost white. |
| Note de contenu : |
- EXPERIMENTAL DETAILS
- RESULTS AND DISCUSSION : Overall appearance - Gloss - Color - Thickness loss - Electrochemical impedance spectroscopy
- FIGURES : 1. Exemplar images of different coatings showing how appearance changed after one month in accelerated weathering. The exposed area is the lower portion of each sample. All figures courtesy of the authors - 2. Loss of gloss measured at 20 degrees in accelerated exposure (top) and in natural exposure (bottom) - 3. Color change after exposure in accelerated weathering - 4. Color change after exposure in natural weathering - 5. Thickness reduction calculated from weight loss of free films in accelerated weathering (top) and in natural exposure (bottom) - 6. EIS results from accelerated weathering of all three samples of each coating. Symbols and colors show impedance data from the same coating formulation. Impedance of the unexposed samples is shown by the open symbols (higher values on each graph). Impedance values after six months are shown by filled symbols - 7. EIS results on panels weathered in Florida and Texas for six months |
| En ligne : |
http://www.paintsquare.com/archive/?fuseaction=view&articleid=6016 |
| Format de la ressource électronique : |
Web |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28372 |
in JOURNAL OF PROTECTIVE COATINGS & LININGS (JPCL) > Vol. 34, N° 2 (02/2017) . - p. 30-42
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