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| Ensuring the quality of stud welding connections in construction |
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Besides modern stud welding equipment, secure welding connections also require skillful construction, the right choice of materials and manufacturing according to up-to-date techniques. The rules for stud welding are found, above all, in EN lSO 14555. Here, among other things, the inspection and testing procedures for, stud welds are laid down. These incIude:
| 1 | Visual test to check the flawlessness of the weld collar and the correct length of the welded stud; |
| 2 | Bend test prior to mass production and further random bend tests during mass production; |
| 3 | Macro-polishing to check the burnt-in joint and investigations to discover any flaws in the connection, cracks or pores which may have arisen from unsuitable materials or welding with incorrect settings. |
| 4 | Transmission and tensile tests are designed to detect any flaws over the whole of the welding surface. As a rule they are only carried out during a company's initial application for certification as a qualified stud welder. |
Studs which have been proved suitable for welding are listed under the standard EN lSO 13918. With any studs included in that list, there is no need for the user to be concerned about unsuitable materials or stud shapes. In addition to the stud shapes and materials listed in the norm, KÖCO can also supply some special studs, for instance extra long shear connectors and threaded studs from high-tensile steel, which are still suitable for welding.
Figure 18: Köco "ELOTOP" series stud welding power sources
Figure 19: "CLASSIC" series KÖCO welding guns
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Comparison of some important characteristics
of |
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| Steel construction | Structural concrete |
| pre-fabrication to a high degree in the factory, independent
of the weather, then quick assembly of prefabricated elements |
production mostly on the building site, dependent on the weather, costly due to elaborate formwork (except when using concrete prefab elements) |
| costly fire protection measures required in buildings
with a high fire risk |
built-in fire protection |
| realisation of large spans possible with relatively little material, light-weight construction | large spans necessitate solid beams and heavy-weight structures |
| sensitive to vibration | insensitive to vibration |
| maintenance (prevention of corrosion) necessary for the structure's entire lifetime | if correctly planned very little necessity for anti-corrosion measures |
| structural changes and adjustment to alternative uses relatively easy |
structural changes and adjustment to alternative uses difficult |
| low costs for disposal after demolition -the debris can be scrapped and recycled | high disposal costs after demolition -the debris is not reusable |