The grade adjustment area of the manhole is the first to suffer deterioration caused by freeze /thaw cycles, traffic loading, thermal expansion and contraction of the surrounding pavement and other external forces
Manholes are the principal means of access to the sanitary and stormwater collection system.
These structures are typically constructed with a narrow vertical chimney section that extends from the top of the manhole cone to the frame. To bring the frame casting to grade and provide the necessary structural support, courses of bricks, blocks or riser rings are positioned on top of the manhole cone before the frame is set. This is referred to as the “grade adjustment” or “chimney” area of the manhole.
Over time, ground movement, thermal expansion and contraction of the surrounding pavement, freeze-thaw lift, and traffic loading can cause the “grade adjustment” bricks, blocks, and riser rings and their associated adhesive or mortar to deteriorate allowing subsurface water to enter the manhole. Depending on soil conditions and initial back-fill methods this water infiltration causes settlement, cave-ins, sink holes and street collapse as the surrounding soils and sub-grade materials flow with the water into the manhole.
Trelleborg FlexRib Manhole Chimney Seals are installed in new manholes to prevent eventual infiltration and to eliminate the infiltration into existing structures, which occurs during wet weather, between the manhole frame and cone through the “grade adjustment” area.
Creates a watertight seal between the frame casting and top of the manhole cone allows the seal to move vertically and/or laterally while maintaining a watertight seal. It's made from a premium quality rubber compound and available in four widths.
Patented Waveband technology creates a more effective seal by concentrating the compressive force of the expansion band. The rubber is “captured” between the band and the concrete.
Needed to order DrainFlexRib Frame-Chimney Seal
A = Inside diameter of manhole frame
B = Inside diameter of grade adjustment area
C = Inside diameter of cone
D = Height of grade adjustment area (bottom of frame to top of cone)
E = Vertical surface on inside of manhole cone
T = Degree of taper on inside of frame
Trelleborg FlexRib Manhole Chimney Seals are made from a premium quality rubber compound and stainless steel bands which are designed to withstand the corrosive environment present in a sanitary sewer manhole
One end of the FlexRib Extension is designed to fit under the FlexRib Seal, allowing them to span up to an additional 8 inches of adjustment. Multiple FlexRib Seal Extensions may be used to span taller grade adjustments.
Technical Approvals, Patents, Quality Standards
In conformance with worldwide standards
In confirmance with European standards
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