PCN – Communicating Advances In Protective Coatings Globally in Real Time
Leading Source of Industry News on Protective Coatings for Oil &Gas, Pipelines, Marine and Construction
Special Edition on Pipeline Coatings
Carboline Wins Award for Anti-corrosion Coating
Graphene Reinforced Composites as Protective Coatings for Oil and Gas Pipelines
Major Conference on Pipeline Coatings Sponsored by Shawcor (12-14 February 2019)
Emerson Launches Corrosion Monitoring Solution for Remote Pipelines
DENSO Awarded Largest Field-joint Coating Contract for EUGAL Pipeline
Construction of Jemena Northern Gas Pipeline Complete
Epoxy Resin Systems and Versatic™ Monomers for Direct-to-Metal Protective Coatings
Problems with Incorrect Mixing Rations of Multicomponent Epoxy Coatings (Editorial)
The component materials of epoxies are designed by the coating manufacturer to react in a particular ratio (chemically known as the stoichiometric ratio) when mixed with their corresponding parts. If the materials are not properly mixed, the chemical reaction will not occur as intended. This can result in reduced coating performance or even complete failure of the coating. In some cases, there is visual evidence of the coating material not being properly catalyzed. An applied coating may sag or appear to be wet and uncured, or remain soft due to an incorrect proportion of hardener to base material. In other circumstances, the coating material appears to be properly cured and exhibits no visual evidence of improper catalysis. However, the electrical resistivity properties of the coating may be altered that can affect performance particularly for cathodic protection (CP) systems.
Most of the common protective coatings for pipelines consist of 2 components (base + hardener) that are mixed together just prior to use. Mixing the components in the proper ratio (e.g. 3 : 1) is critical to the performance of the coating. If the ratio is off, curing and performance problems can occur. An incorrect ratio can occur due to one or more of the following reasons:
– the proportions of Part A and Part B are are not correctly dosed due to volumetric errors with the metering and pumping equipment
– batch-to-batch variations in density of the Part A and Part B;
– entrained air during mixing;
– viscosity mismatch due to incorrect component temperatures;
It can be very challenging for field workers in an outside production environment to take the extreme care that is necessary to carefully measure and mix kits or drums. While laboratories can do this under very controlled ambient conditions and with graduated cylinders and balances, it requires a great deal of discipline and attention to details to get it right.
When partial kits are mixed, the individual components must be thoroughly blended before extracting the material. After a portion of the coating is removed, the containers must be immediately and thoroughly sealed, otherwise volatiles in the containers can escape, effecting later mixes. In the case of epoxies and urethane-epoxies, moisture in the air can create problems when sealing is inadequate. Some epoxy hardeners such as AEP can react with water.
While mixing a coating may seem like a simple task, the impact that it can have on coating performance is significant. Improper mixing can lead to an incomplete chemical reaction, resulting in reduced coating performance. By contrast, a proper mix will give a coating material the best chance to perform as intended. Every coating is designed by its manufacturer to be mixed and applied properly. Diligently following the manufacturer’s specifications for coating preparation will increase the likelihood of peak coating performance.
Testing and Analysis of Two-component Epoxy Coating Pipeline Coatings for Correct Mix Ratio (Lab Service)
Keywords: Mix Ratio Analysis of Protal 7200, Failure Analysis of Pipeline Coatings, Testing of Denso Protal 7200 , Testing of Canusa HBE95
This newsletter is brought to you by ExcelPlas Coating Labs (http://www.excelplas.com/)
ExcelPlas Labs provides independent testing, analysis and investigation on protective coatings to prevent corrosion.
ExcelPlas has extensive analytical capabilities for testing of Protective Coatings and Insulation Consulting for major oil and gas companies.
We conduct corrosion surveys, coating sampling, coating analysis and testing to ensure coating specifications for a wide range of onshore and offshore clients in Australia and the Asia-Pacific Region.
ExcelPlas Labs offer a full range of coating testing and analytical services to Australia’s mining, oil, gas and infrastructure sectors.
Forensic analysis for undertaking various coating based failure investigations and problem solving.
ExcelPlas Undertakes Analysis & Testing of Polymer Coating Systems including:
• Epoxy Protective Coatings
• Epoxy-Phenolic Protective Coatings
• Fusion bonded epoxy (FBE)
• Dual-Layer Fusion bonded epoxy (DLFBE)
• Liquid applied epoxy (LAE)
• Abrasion resistant overcoat (ARO)
• Three-layer PE (3LPE)
• Multi-component liquid spray (MCL)
• Heat shrink sleeves (HSS)
Testing on Coatings that ExcelPlas can Undertake includes:
• Coating identification by Infra-red Analysis (FTIR)
• Degree of Cure by Thermal Analysis (DSC)
• Coating Filler Identification by X-ray Analysis (EDS/XRD)
• Coating Microstructure by Embedding, Polishing and Optical Microscopy (OM)
• Coating Thermal Stability and Composition by Thermogravimetric Analysis (TGA)
DSC – Phase transition/volatiles / Tg / degree of cure/characterisation
TGA – Volatile compounds, inorganic mass % mix ratio
Element mapping for chlorides on paint flakes
Microscopy -Count layers and thickness of layers
-Assess porosity and voids
-Check distribution and orientation of filler particles
Condition monitoring and analysis of corrosion prevention coatings (epoxies, epoxy-phenolics)
Testing of Epoxy Coatings (LAE, FJC, FBE), heat shrink sleeves and tapes, barrier tapes and meshes.