BE-15 Pipes and Materials: Welding of Plastic Pipes

Heating element butt welding

Quality assurance for the heating element butt welding

Table: 
Quality assurance measures during heated element butt welding [FI-Steina]

Measures Details
Assignment of skilled technical staff Requiring personnel with welding certificates
Protecting welding area from climatic influence (solar radiation, effects of humidity, wind and temperatures below +5 °C) Preheating, covering under canopies, heating, closing of pipe ends opposite the welding positions
Inspection of incoming goods Visual controlling of the components to be welded (notches, scratches, etc.)
Control of welding additives, when used Welding additive should generally consists of the same material as the joining parts and has to be clean and dry
Cleaning of semi-finished products
The bonding surfaces of the parts to be welded must be free from contamination. Mechanically removing of soiling, separating layers, oxidation layers etc. are required.
Cleaning agents (e. g. acetone) which dissolve attack or modify the surface of the plastic or cause them to swell must not be used.
Cleaning must be carried out immediately before welding.
Cleaning of heating element
Teflon films and coatings make cleaning the heating element easier and prevent the plastic sticking to the heating element when hot. This is particularly necessary when welding PVC.
Cleaning must be carried out immediately before welding
Controlling temperature of heating element
Heating element must have had the desired temperature for at least 10 minutes before it may be used for welding.
Temperature of the extruded material measured at the nozzle mouth has to be in a range of 210 – 230 °C for HDPE
Welding parameters Correct calculation and maintenance of welding periods, welding temperatures and welding pressures
Non-destructive testing of welding seam Visual inspection, ultrasonic testing, x-ray testing
Monitoring of welding work Welding protocols or documentations (melting temperatures, welding period, jointing pressure, etc.)

 

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