ORIGINAL ARTICLE Impact analysis of clearance occurring between polymeric pipe and connector in the process of electrofusion (EF) weldment of pipes Mohammad Riahi & Hosseinreza Arab & Mohammad Faraji Ghanati Received: 5 December 2009 / Accepted: 10 January 2012 # Springer-Verlag London Limited 2012 Abstract In this investigation, all parameters having impact on quality of electrofusions (EF) welding of polyethylene pipes were reviewed. Among those outstanding points rec- ognized, one has been carefully and selectively studied. Impact of clearance between fittings and pipes and its effect on the strength of EF weldment at such a location has been chosen for analysis. Obtained results from modeling of finite element of EF fitting in ANSYS have been compared with the actual experiments conducted in the welding process. Convergences of the findings on comparison basis are satis- factory. Quality of welding has been measured mechanically through tension testing of the welded pieces. Two points in particular have been scrutinized while conducting the test: first, tensile strength of the weld and then elongation of the weld surface at rupture point. Keywords Electrofusion welding . Polyethylene pipes . Clearance of pipe and connector 1 Introduction Electrofusion (EF) fittings are increasingly utilized in polyeth- ylene (PE) networks. Consequently, recognition of important parameters having effective impact on the quality of this type of welding in polyethylene pipes has a high priority. Figure 1 depicts the socket coupler type of EF fitting. Jeremy Bowman [1] has analyzed heat distribution as well as pressure change in the EF coupler by computer simulation. In his paper the process of electrofusion joining is reviewed by examining the experimental and some com- puter simulation literature relating to the temperature and melt pressure changes during the fusion process and on how varying fusion time influences the strength of electrofusion joints. In this paper there is also an experimental result explaining influence of pipe/fitting gap on peel energy of weld specimens. From his literature review, four key stages in the electrofusion joining are identified. First is the incu- bation period where the joint has no strength. Second is a joint formation and consolidation stage where increasing joint temperature aids molecular diffusion to both increase the joint strength and promote more ductile mode of failure. A plateau region then follows where the joint strength and ductility remain reasonably constant despite the fusion time increasing. Finally there is a cooling stage where the joint bridging “tie molecules become locked into either side of the joint.” It is these tie molecules that give the joint its ductility and strength. On the other hand, Maine and Stafford [ 2] measured heat temperature distribution occurring in the EF coupler process in different locations on the weld surface. Donogue et al. [3] have studied temperature distribu- tion around heating elements on the surface of welded EF connections. Returning to process modeling, they produced simulation analyses using a commercial gen- eral purpose FE package, Abaqus. The work formed part of an ongoing research project sponsored by the Gas Research Institute (USA) to enhance the EF joining technique for the US gas industry. They claimed that their 1D axisymmetric model is valid based upon the assumption that the temperature distribution in the center of the wire region is relatively independent of axial effects. Thus M. Riahi (*) : H. Arab : M. F. Ghanati Center for Advancements in Mechanical and Nondestructive Testing, School of Mechanical Engineering, Iran University of Science and Technology, Tehran 16887, Iran e-mail: riahi@iust.ac.ir Int J Adv Manuf Technol DOI 10.1007/s00170-012-3910-0