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Man Entry Mechanical Seals

Overview
This No-Dig technology is a low profile mechanical seal specially designed for the internal repair of leaking pipe joints. A robust section of rubber spans the joint and is installed using the hydraulic expansion of stainless steel compression rings, thus eliminating the use of chemical additives and their associated hazards. For use in potable water pipelines, each seal must have WRAS approval and have a life expectancy of more than 50 years.
The benefits of such a repair system include its: capability, flexibility, small working area, reduced carbon footprint and cost effectiveness making it a true No Dig repair solution.
Application
Any man-entry or man-accessible pipeline to a maximum diameter of 3,650mm subject to an internal survey to determine the suitability of the pipeline to this non-structural joint or small defect repair system.
Technology Description
This technology is a low profile mechanical joint seal specially designed for the non-structural internal repair of leaking pipe joints and other defects. A robust section of rubber spans the joint and is installed using the hydraulic expansion of stainless steel compression rings, thus eliminating the use of chemical additives and their associated hazards. The long term life expectancy should be at least 50 years. This method provides a good example of trenchless technology: capability, flexibility, small working area and reduced carbon footprint to provide an efficient and cost effective solution for repairing leaking pipe joints and similar defects. For potable water use, each seal requires WRAS approval.
A pipeline must be surveyed for condition and suitability, including an accurate internal diameter measurement.
Two stainless steel retaining rings are placed in position and the seal's position is adjusted before the stainless steel rings are expanded hydraulically and secured with stainless steel wedges.

The seal is thoroughly checked and pressure tested by inflating the seal to ½ bar with compressed air through its integral test valve and a soap test completed. For pressurised pipelines, a polypropylene backing band is installed to protect the seal rubber from compression damage from the hard shoulders of the pipeline joint.
If the pipe material is steel or iron, a suitable anticorrosive system is agreed before the contract commences; and if the pipeline carries potable water, then any replacement protective coating must conform to DWI Regulation 31.
This is a proven flexible, robust mechanical seal which does not suffer from the shortcomings of traditional chemical sealants and grouts and can be used in pipelines of any diameter where safe man-access can be achieved - such seals have been installed in pipeline diameters from 500mm to 3,650mm. The seals can be used in both pressurised (up to 25 bar) and non-pressurised pipelines and in pipelines with steep gradients and in vertical pipes.

Due to the technology used, the seals can accommodate expansion, elongation, contraction, displacement or rotation and a variation can accommodate a stepped joint as the rubber of the seal spans freely across the joint and is only fixed to the pipe walls on either side of the joint. The seal can also be installed to pipe joints having two different materials by installing to the pipe walls on either side of the joint and to pipes of different diameter (within limits) by increasing the size of one of the two the steel retaining bands.
This 100% mechanical seal is a complete No-Dig technology and uses a minimum of materials, involving no adhesives or chemicals which in turn contribute to the significantly small carbon footprint.

installed Seal

Installed 800mm dia seal.
Image by courtesy of Planned Maintenance (Pennine) Ltd.

2016 AMEX-10 END SEAL cross-section by Scott Dawson

Section through Typical Mechanical Joint Seal
Diagram by courtesy of Planned Maintenance (Pennine) Ltd.

installed Seals 1

Series of installed seals in a 800mm dia water trunk main.
Image by courtesy of Planned Maintenance (Pennine) Ltd.

Last Updated on Wednesday, 25 January 2017 14:21

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