The
secondary seal reduces the evaporation losses of the primary seal, and it also
prevents the rainwater and other products from falling into the stored
products. The compressed plates may be mounted on horizontal or vertical type
of roof rims and made to accept specific bolt pitching. The overlapping of
compressed plates give strong sealing pressure to the tank shell. The wiper tip
complies with a UV and weather resistant type of synthetic rubber and exerts a
high sealing efficiency. The shunts comply with API 2003.