process feature | Pipe joining
Krah’s E-Box 44 MS socket
welding device was developed specifically for large diameter pipes
Four jaws adjust to any desired spacing and each jaw clamps individually which allows for a greater combina- tion of pipe and fitting sizes. This flexibility is especially beneficial when fusing large assemblies. There is a removable outer fixed jaw, and the device’s rack and pinion drive provides smooth and steady fusion force, says the company.
Fitting end At a recent in-house event, German pipe machinery specialist Krah showed the HAS-System – a fitting welding system based on the principle of the heating element socket welding. The system is suitable for branches at all kinds of
helically wound pipes, and branches at direct extruded pipes. It works for pipes of OD 125-225mm and is specially designed for the requirements of sewer pipe systems.
The HAS-System is also applicable for solid-wall pipes and profiled pipes from OD 225mm. Fittings can be welded into all plastic pipe systems out of HDPE and PP. In comparison to mechanical jointed branches, the HAS-fitting has 100% safety and water-tightness, says Krah – delivering a homogenously welded branch with smooth surfaces to avoid any additional disturbance for the flow media/sewage. Fittings are attached in a seven-step process, which
takes around 15 minutes for pipes with an 85mm wall thickness. First, a hole is drilled with a hole saw and then a clamping-device is fastened on the pipe. Using a milling device, a conical shape is for the heating element – which then heats the fitting and pipe. After the recommended heating time, the HAS fitting is pressed into the main pipe. (To do this as quickly as possible, the heating elements have a lifting device.)
Welding advice
TWI and plastic welding specialist Branson Ultrasonics recently presented a joint technical seminar at TWI’s facilities in Cambridge, UK. The event, called New developments in plastics welding, aimed to
help delegates gain a better understanding of the latest plastics welding technologies and processes. It featured presentations on topics including laser, vibration and
friction stir welding, the use of computed tomography in failure investi- gations, and ultrasonic staking. Demonstrations included TWI’s micro computed tomography and phased array ultrasonic inspection systems. Mike Troughton, chair of the Polymers Technical Group at TWI, said:
“Delegates were keen to increase their knowledge of the advances in this technology, and learn more about plastic welding processes in general.” TWI offers a number of services relating to the welding of polymers, including process selection and optimisation, testing and joint design.
40 PIPE & PROFILE EXTRUSION | June 2016
www.pipeandprofile.com
After a fast cooling time, the welding device can be removed. The seventh step is optional: a scraper tool can be
used to remove the protruding parts of the welded fitting inside the main pipe, making it absolutely flush-mounted. No leftovers protrude into the main channel, which could cause additional flow disturbance. At the same event, Krah unveiled its E-Box 44 MS
socket welding device – an extension of its earlier E-Box 33. It was developed specifically for large diameter pipes. Until now, two separate devices were needed for the welding process, as a pipe diameter of DN1400 needed two heating circles for the welding process. If smaller pipes can be welded with a single heating
circle, it is possible to weld two pipes at the same time. Simultaneous welding of pipes with different diameters and welding parameters is also possible at any time – because welding parameters can be applied indepen- dently.
Other feature includes: a welding area up to DN4000mm; automatic logging of up to 10,000 proto-
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