Available in sizes 50 – 1200 mm diameter the FLEX-TEND® has both defleciton and expansion capability.
Up to now, geological hazards have been ignored or left to the probabilities of nature. However a new pipeline usually represents considerable replacement costs at a future time. The time to make the most economical impact on the system reliability is during the initial planning and design phase through application of proper lifeline earthquake engineering principles.
Within the past few years, significant progress and technological improvements have been made in the ductile iron industry with regard to jointing systems that withstand seismic activity; telescoping sleeves and flexible couplings are used, as are standard restrained joints and high deflection ball and socket joint pipe. These unique couplings and joints are specially designed for use in fault zone areas. Prudent design using these specific jointing/coupling systems will significantly promote continuity and performance during seismic activity.
Rigid connections to water storage tanks present a highly vulnerable design based on seismic activity. An economic and effective solution can be achieved using a flexible expansion/contracting coupling. This type of device provides strength and flexibility at the joints, as well as the ability to lengthen or shorten.
The Porirua City Council in NZ recently installed a 300mm with 300mm expansion Flex-Tend® on a 1 million gallon reservoir tank and has plans to retrofit another 17 FLEX-TEND®S on reservoir tanks over the next 5 years.