Internal lining of gate valves
A global valve manufacturer engaged IND to apply a highly durable coating to an order of metal gate valves to ensure they meet their required durability.
IND was chosen to apply an internal coating to 11 gate valves ranging in size from DN200 to DN900.
The project had strict quality requirements and involved the OEM manufacturer and asset owner (SA Water) conducting daily QA/QC inspections to ensure the coating was of the highest quality and would meet the requirement for a 50-year service life. All works were overseen by our in-house NACE 2 inspectors and followed our strict inspection and test plan (ITP).
Belzona 1341 was chosen due to its outstanding durability, fluid efficiency and AS 4020 testing certification and suitability to contact with drinking water. Over 100kg of product was applied and the project took four weeks to complete.
Project overview:
ITP & methodology development
Abrasive blasting
Coating application
QA inspection and reporting
Surface Preparation
The valves, gates and bonnets all contained steel and brass mating surfaces designed to tight tolerences that needed to be protected from the blasting and coating processes.
Coating Application & Quality Assurance
Each of the valve, gate and bonnet bodies were then coated with three coats of Belzona 1341, each of approximately 200μm thickness totaling 600μm to ensure adequate protection of the steel substrates. The three coats were applied blue-grey-blue as a visual wear indicator if any of the top blue layer is ever damaged.
In-between each of the coats, the Belzona was visually inspected including using mirrors to ensure the coating had been applied throughout, especially on the obscured surfaces inside the valves. Dry film thickness inspections were conducted ensuring each coat was to specification as well as pull-off adhesion tests on test plates ensuring the coating adhered.
The final QA inspection was Holiday Detecting where we ran 2,000 volts over each surface ensuring there were no missed or thin areas leaving the substrate vulnerable to corrosion. All eleven valve bodies passed their inspections and were dispatched along with their QA documentation.
