Inspections & Tests for FBE Coating Steel Water Pipes

AWWA C213 is the standard specification for fusion-bonded epoxy coatings for steel water pipes and fittings installed underground or underwater. A series of inspection and tests shall be conducted to ensure the quality, durability, and corrosion protection provided by FBE coatings applied to the steel water pipes, thereby ensuring the long-term performance and reliability of water distribution systems.

Physical properties for epoxy powder materials

FBE coated seamless steel water pipes 8″ SCH20, supplied to Liverpool, the UK.

The specific gravity, sieve analysis, and gel time of the epoxy powder shall be tested: (1) Specific gravity of the epoxy powder shall be determined using a Beckman Model 930 air comparison pycnometer or by hexane displacement (method B of ASTM D153). The value shall be between 1.2 and 1.8 at 23°C [73°F]. (2) The sieve analysis of the powder shall be conducted in accordance with method D of ASTM D1921 using an Alpine sieve unit. Sample size shall be 25 g. Sieve size shall the US standard 100 mesh (150 μm). The percent of material retained on the 100-mesh sieve shall be no greater than 2. (3) Gel time shall be determined by placing approximately 0.1 g of powder on a hot plate stabilized at 204°C±2°C [400°F±5°F]. Use a wooden spatula to coat at least 650 mm² of the plate. Start a stopwatch as soon as the powder becomes molten. Continue to stir the molten epoxy material and stop the watch when the epoxy becomes so gelatinous that it can no longer be stirred. The gel time shall be greater than 7 seconds.

Prequalification requirements of epoxy system

Inspections and tests shall be conducted on testing samples to determine the pre-qualification requirements of the epoxy system:

• Appearance. The coated impact panels shall be visually inspected for appearance. The cured epoxy shall be of uniform color and gloss and shall be free of blisters, pinholes, fish eyes, or other irregularities.
• Impact resistance testing. Test for impact resistance shall be conducted in accordance with ASTM G14 and at a thickness of 12-14 mil. The impact epoxy shall not crack or disbond at the point of impact. Inspection for failure shall be performed using a wet-sponge 67.5-V holiday detector in accordance with NACE SP0188.
• Bendability. Prepare one cold-rolled steel plate 25 mm x 203 mm x 3.2 mm with the proper fusion-bonded epoxy coating as instructed. Bend the coated plate over a mandrel with a radius of 159 mm. The epoxy shall not crack or disbond.
• Shear adhension. Prepare one cold-rolled steel plate 25 mm x 152 mm x 3.2 mm with the proper fusion-bonded epoxy coating as instructed. Shear adhension shall be determined in accordance with ASTM D1002. The minimum value shall be 3000 psi.

FBE coated steel water pipes supplied to Dubai, UAE; 6″ STD L=6 meters.

• Penetration test shall be conducted in accordance with ASTM G17 at 60°C [140°F] and the value attained shall be less than 10%.
• Abrasion resistance shall be conducted in accordance with ASTM D4060 with a CS-17 abrasive wheel and 1000-g loading. The maximum 5000-cycle-loss shall be 300 mg.
• Water soak test shall be conducted at 95°C [203°F]. 1~3 pass is accepted.
• Dielectric strength of the epoxy shall be inspected in accordance with ASTM D149 and its value shall be no less than 39.4 V/mm [1000 V/mil].
• Volume resistivity of the epoxy shall be tested according to ASTM D257 and the value shall be less than 1.1 x 10¹⁵.
• Cathodic disbondment of the epoxy coating system shall be be determined in accordance with ASTM G8. The average value shall be no greater than 15 mm.

Quality control requirements of applied epoxy system

• The epoxy coating applied to the steel water pipe shall have no blisters, cracks, bubbles, delamination, or other visible defects. There shall be no wet or sticky areas in the epoxy.
• On completion of the epoxy coating on the steel water pipe but before storage, electrical inspection for continuity shall be conducted in accordance with NACE SP0490. No defects shall be found.
• Thickness measurement verifies that the FBE coating meets the specified thickness requirements. This can be accomplished using non-destructive methods such as magnetic induction or ultrasonic measurement techniques. The thickness value measured shall be no less than 305 μm (12 mil).