Sealing systems in bolted metal tanks are a critical component for ensuring the tank's watertightness and hydraulic integrity. Due to the presence of bolted joints between panels, proper sealing determines the tank's long-term reliability against leaks, internal corrosion, and degradation. There are two main technologies: mastic sealing and flexible membrane or liner sealing.

The mastic sealing system involves applying a sealant between the joints of the bolted panels, creating a continuous barrier that prevents fluid from escaping. This method relies on the chemical adhesion of the mastic to the metal surface, utilizing the compression generated by the bolts to ensure uniform sealant distribution.

From an engineering perspective, mastic offers several advantages: the tank maintains direct contact between the fluid and the inner lining—galvanized, epoxy, stainless steel, or vitreous enamel—without the need for additional lining. This facilitates internal inspections, cleaning, and maintenance in galvanized or lined tanks, and also allows for higher operating temperatures compared to flexible membranes.

Mastic performance depends on factors such as:

• chemical compatibility with the stored fluid
• maximum serving temperature
• maintaining the tightening torque
• integrity of the interior coating