Menu
Search
Filters
Close
Menu

Changes in Appearance and Corrosion Protection of Polyurethane Pipeline Coatings During Weathering Exposure

Changes in Appearance and Corrosion Protection of Polyurethane Pipeline Coatings During Weathering Exposure
Available for download

Very thick polyurethane coatings are used to provide corrosion protection for water pipelines that must be placed below ground and then may be exposed to ground water. Occasionally there are construction delays and pipe sections remain above ground for extended periods before installation. Under these conditions, atmospheric conditions and exposure to solar UV light cause the coatings to lose gloss and become yellow. These changes can be very obvious and thus raise concerns that the corrosion protective qualities of the coating have also similarly diminished. 

Product Number: 51217-038-SG
Author: S.G. Croll, C. Gu, V. Upadhyay, B.D. Keil,
Publication Date: 2017
Industries: Pipelines, Tanks, and Underground Systems , Corrosion Monitoring and Control , Coatings
$0.00
$20.00
$20.00

Very thick polyurethane coatings are used to provide corrosion protection for water pipelines that must be placed below ground and then may be exposed to ground water. Occasionally there are construction delays and pipe sections remain above ground for extended periods before installation. Under these conditions, atmospheric conditions and exposure to solar UV light cause the coatings to lose gloss and become yellow. These changes can be very obvious and thus raise concerns that the corrosion protective qualities of the coating have also similarly diminished. Aromatic polyurethane coatings have been subjected to 6 months accelerated laboratory weathering as well as continuing natural weathering in Florida and Texas. The accelerated weathering caused very large, rapid changes in appearance but did not provoke any significant reduction in corrosion protection, as assessed by electrochemical impedance spectroscopy. Coating degradation was quantified with gloss, color, thickness loss (by weight change) and impedance. Coating thickness remains almost at its starting value which provides the corrosion protection, whereas the appearance changes are caused by changes in the outer surface of the coating. Thus, in such circumstances, for very thick coatings, appearance changes do not correlate with corrosion protection. It is well known that accelerated and natural weathering are difficult to correlate quantitatively, but natural exposure of only 6 months produced similarly obvious changes in appearance and small changes in corrosion protection.

Very thick polyurethane coatings are used to provide corrosion protection for water pipelines that must be placed below ground and then may be exposed to ground water. Occasionally there are construction delays and pipe sections remain above ground for extended periods before installation. Under these conditions, atmospheric conditions and exposure to solar UV light cause the coatings to lose gloss and become yellow. These changes can be very obvious and thus raise concerns that the corrosion protective qualities of the coating have also similarly diminished. Aromatic polyurethane coatings have been subjected to 6 months accelerated laboratory weathering as well as continuing natural weathering in Florida and Texas. The accelerated weathering caused very large, rapid changes in appearance but did not provoke any significant reduction in corrosion protection, as assessed by electrochemical impedance spectroscopy. Coating degradation was quantified with gloss, color, thickness loss (by weight change) and impedance. Coating thickness remains almost at its starting value which provides the corrosion protection, whereas the appearance changes are caused by changes in the outer surface of the coating. Thus, in such circumstances, for very thick coatings, appearance changes do not correlate with corrosion protection. It is well known that accelerated and natural weathering are difficult to correlate quantitatively, but natural exposure of only 6 months produced similarly obvious changes in appearance and small changes in corrosion protection.

Product tags
Also Purchased
Ceramic Epoxy Coatings in Immersion
Available for download

Ceramic Epoxy Coatings in Immersion

Product Number: 51217-070-SG
Author: Ben Rowland
Publication Date: 2017
$20.00

Due to its success in the ductile iron wastewater pipe market, ceramic epoxy coatings are being increasingly specified and successfully applied on nearly every substrate used for immersion service in both the water & wastewater industry. Some unique characteristics set these epoxy coatings apart from their traditional counterparts. For instance, ceramic epoxy systems provide high-film builds, eliminate undercutting, minimize permeability, provide superior edge retention and form a non-ablative film.
Causes of Coating Failures
Available for download

Causes of Coating Failures

Product Number: 41209-512-SG
Author: Kenneth B. Tator
Publication Date: 2009
$20.00

Industrial and marine protective coating systems are most commonly applied without incident and perform as expected over their anticipated service life. However, occasionally, a coating system will fail prematurely, for unexpected reasons, and with expensive consequences. This paper addresses those unexpected failures and provides reasons and remedies for such occurrences.
Clarifying Material Selection: Understanding the Corrosion Mechanisms for Wastewater Clarifier Mechanisms
Available for download

Clarifying Material Selection: Understanding the Corrosion Mechanisms for Wastewater Clarifier Mechanisms

Product Number: 51217-060-SG
Author: D. A. Sherman, R. A. Nixon
Publication Date: 2017
$20.00

Wastewater treatment plant clarifier environments present challenges for selecting materials of construction. Coated carbon steel, hot-dip galvanized steel, and stainless steel are most commonly specified for new or refurbished clarifier mechanisms, and all have their advantages and disadvantages with regard to achieving the intended design life. 
Categories
Industry
Recently viewed
Popular tags
View all

Association for Materials Protection and Performance

© AMPP All Rights Reserved.
Membership Terms of Content Use
Contact Customer Support