Performance Requirements for Elastomeric Sealing Pipe Joints – Water Supply and Sewerage
This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.
Report no. UWRAA 138
Poor performance of pipe joints in water and sewerage pipelines means that water authorities unnecessarily spend millions of dollars annually in treatment and maintenance work, such as clearing root intrusions and blockages. Some of this poor performance occurs because of the lack of adequate joint performance requirements in Australian pipe standards. The current performance requirements given in standards for elastomeric sealing rings used in pipe joints have a number of inconsistencies across the different pipe material types. They are either currently unnecessarily restrictive through the use of prescriptive property requirements or inadequate in that they define minimal or no performance requirements. These problems increase costs, reduce freedom to take advantage of developments in technology and adversely affect competitiveness in export markets.
In this report, previous and current research on the performance and evaluation of elastomeric joints is reviewed and the inconsistencies across the different pipe material types are discussed. To establish a background to the development of pipe and pipe joint systems, with a focus on elastomer joint design, a survey was conducted among a range of rubber manufacturers, pipe manufacturers and water authorities. Based on the information from both the survey and a literature review, the ability of elastomeric joints to resist root intrusion has been highlighted as the main performance requirement necessary for sewerage pipelines. Experimental assessment of root intrusion using sewerage pipe materials such as vitrified clay, plastic and fibre-reinforced cement has been undertaken using various types of common joints, with different levels of interface pressure. A finite element modelling technique is described for evaluating whether the interface pressure between rubber ring and spigot and socket, under shear load conditions, is adequate to stop sewer infiltration and exfiltration. Finally, uniform performance requirements for elastomeric pipe joints for pressure and non-pressure pipeline system components are proposed.