FrankPKSNZ develops unique earthquake pipe-coupling solution
As major repair work continues to underground piping networks damaged by Canterbury’s earthquakes, Christchurch-based company FrankPKS has developed a ‘New Zealand first’ producing an Earthquake Expansion Coupling for large, high density polyethylene (HDPE) pipes.
The company produces large-bore HDPE pipes from its manufacturing facility in Bromley and has been extensively involved in supplying HDPE pipe solutions to major contractors for the repair of the city’s earthquake damaged wastewater and sewer system.
“The value of flexible HDPE pipes has been repeatedly proven throughout this years devastating events in both Canterbury and Japan, with no significant damage occurring to the piping itself ” said general manager Bryan Wilson.
“However, the ongoing series of aftershocks in Canterbury, particularly during repair work, has highlighted potential weaknesses at the point where PE pipes are connected to static objects such as building foundations, sump walls and existing concrete sewer systems” he said.
The company has developed a new Earthquake Expansion Coupling with welded ‘break points’ which will withstand small to medium-sized earthquakes but which are designed to shear apart under larger earthquake pressure.
This allows the pipe inside to move freely, sliding backwards and forwards through the coupling instead of damaging the static structure that the pipe and collar are attached to.
“The Canterbury Earthquake has thrown up some unique challenges due to the multi-directional movement and the huge variation in the amount of lateral spread occurring in surrounding soils ” said Mr Wilson.
"Once Geotech engineers have determined the expected spread we can individually custom-build each Expansion Coupling to compensate for that movement. This will give much greater flexibility and confidence in the long term viability of any repair work undertaken ” he said.