Bitumen Tank Heating Coil

Function

Maintaining bitumen viscosity within the correct pumpable range — typically 150–200 cSt at injection — is critical to spray-bar performance and binder coating uniformity on aggregate. Too cold, viscosity rises sharply: pumps cavitate, spray bars clog and binder coating on aggregate is patchy. Too hot, binder oxidises, losing penetration grade and causing premature pavement ageing. The heating coil provides even, distributed heat input that avoids localised overheating while maintaining bulk temperature across the full tank volume. Coil degradation through scaling, corrosion pitting or cracked welds reduces heat transfer efficiency and risks binder contamination if a tube breaches.

Construction & quality

Tube material: seamless ASTM A106 Grade B carbon steel, 38–50 mm OD, 3.2–4.0 mm wall thickness, suitable for 350 °C (662 °F) continuous service. Tube ends are rolled-and-welded or socket-welded to 150 # carbon steel flanged headers. All welds are full-penetration butt or fillet welds; weld seams are dye-penetrant tested before assembly. Each completed coil is hydraulic-pressure tested at 1.5× design pressure (typically 9–12 bar test pressure) before dispatch. Coil form is helical for cylindrical tanks or U-tube serpentine for rectangular tanks, with stand-off spacers to maintain tube pitch and allow free bitumen circulation around the coil exterior.

When to replace

• Bitumen bulk temperature failing to reach or hold target at normal heating-medium flow rate and inlet temperature.
• Visible external corrosion, pitting or discolouration on tube surfaces during tank cleaning inspection.
• Foamy, bubbling bitumen at working temperature — indicates water or steam ingress from a tube breach.
• Heating medium pressure drop across the coil increasing more than 15 % above original design value.
• Localised bitumen carbonisation or discolouration near tube surfaces, indicating scale build-up and hot-spot formation.