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The table below presents the quality assurance measures that must be followed during the process of electrofusion welding. (Table: Quality assurance measures during electrofusion welding) |
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The following standards and regulations offer guidelines for electrofusion welding processes. (Table: US standards and regulations - electrofusion) |
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The following European standards and regulations offer guidelines for electrofusion welding processes. (Table: Standards and regulations for electrofusion welding (as of 12.2005) [FI-Steina]) |
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The table below offers an excellent comparison between the heating element butt welding and electrofusion welding processes. (Table: Comparison of plastic welding methods) |
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Extrusion welding is applied for example in the following fields:
(Image: Watertight welding of the stud course and Preliner) (Image: Extruder-welding device – end of welding procedure) |
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(Image: Attention!) The join faces and adjacent edges must be machined before welding (e.g. with a grinder). Zones that are damaged by climatic or chemical influence have to be reduced down to undamaged areas. Detergents that have swelling effects on plastics may NOT be used for cleaning the joining areas. (Image: Roughening the stud course for later welding) |
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The extrudate is provided by the extruder with a constant mass flow and added to the welding shoe of the seam. This influences the inlet and pressure of the extrudate in the joint, as well as the shape of the seam. (Image: Possible shapes of welding seams during extrusion welding) (Image: Attention!) The welding seam results as a dependent variable from the mass flow of the extrudate and the necessary seam-filling volume. (Image: Possible shapes of welding … |
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(Image: Welding the top hat sleeve - detail) The welding shoe is well adapted for the geometry of the joint and enables the development of hydrostatic pressure in the welding seam joint: it encloses the extrudate, forming a chamber that is closed in front and at the top. At the same time,the welding shoe shapes the upper side of the seam [Gehde03]. |
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After the joining process is carried out under pressure, a substance-to-substance bond is produced during the subsequent unpressurised cooling-off phase. The thermal contraction and recrystallisation of the material leads to a volume reduction of the welding seam of up to 8 % [Gehde03]. (Image: Attention!) In order to enable the sinking of the seam during the cooling-off phase and, therefore, to work against cavity formations in the center of the seam, … |
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The following measures must be taken for quality assurance purposes during extrusion welding. (Table: Quality assurance measures during extrusion welding) |
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The following US standards and regulations provide the necessary guidelines to follow for extrusion welding. (Table: US standards and regulations for PE pipe joining procedures) |
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The following international standards and regulations provide the necessary guidelines to follow for extrusion welding.
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Nov 04, 2016 The following US standards and regulations can be used for welding tests. (Table: US standards and regulations for welding tests) |
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Nov 14, 2016
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Congratulations! You have successfully finished this lesson. Next you will have the opportunity to review the newly acquired knowledge with an interactive questionnaire. You can of course still navigate back to any point in the lessons if you wish to review a specific point or subject. Stay curious! |
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Nov 04, 2016 This module focuses on the theoretical background and the practical conditions to be observed on the subject of welding of polyethylene pipes for gas, water and wastewater pipelines. A further focus is on the requirements to be considered in quality assurance and in particular the consequences of non-compliance. After completing this module, you will have a sound knowledge of:
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