Mechanical seals utilise a sprung metal frame into which a rubberised/EPDM seal is placed.
The unit is placed around an inflatable packer and winched or pushed into position in the pipe with the aid of a CCTV camera system to guide the operator. Once in place the packer is expanded to push the seal against the pipe inner wall. The design of the steel frame allows the seal to lock-out using toothed catches to form a tight seal against the pipe wall. In man-entry sizes the seals can be installed manually without the need for the inflatable packer or the use of CCTV for positioning. There are a variety of manufacturers of these types of seals and the size range available from each varies but can be from 150 mm up to 3.5 m diameter from various indications. The units can be used in most if not all pipe types including: concrete, steel, ductile iron, clay, plastic and GRP. They can also be manufactured to fit irregular shaped pipes (egg, ellipse, oval).