Innovative Stainless Steel Applications in transport ... - Euro Inox

After welding, the joint is finished by grinding. The quality of the weld is controlled by
continuous non-destructive testing or, if required, by other methods (e.g. a flattening
test). Structural hollow sections are cut to the desired length, bundled, strapped and
either transferred to the shipping warehouse or sent for further processing. The hollow
sections are identified by continuous inkjet marking and bundle-specific tags.
The mechanical properties of hollow sections change as a result of cold forming. These
changes depend on the manufacturing method and the dimensions of the hollow section.
The mechanical properties of a ready-made hollow section can be tested by making test
specimens of the hollow section and by material-characterisation testing (Yrjölä 2008).
Production of single hollow sections
In the case of single hollow sections, the base material is a cut sheet corresponding to
the dimensions of the hollow section. The sheet is made circular using a press break
machine, in a number of stages, after which the open profile is welded into a hollow
section by a longitudinal weld, at a welding station. The weld and surface are finished at
separate work stations. Steel strip can also be directly formed into a rectangle by
bending it from the corner zones and welding the seam. These methods are used for
manufacturing stainless structural hollow sections that cannot be produced by roll
forming because of their dimensions or the size of the batch.
3.1.2. Structural design aspects for hollow-section joints
When designing joints and connections, several factors must be taken into account. For
example, the mechanical strength and corrosion resistance of joints and connections
must be ensured, the manufacture and inspection of the joints and connections must be
properly carried out and defects due to difficult installation must be avoided.
Furthermore, in welded joints and connections, particular attention must be paid to the
following:
- Welds should be located outside high-stress and stress-concentration areas.
- It must be possible to make all welds in the design.
- It must be possible to carry out post-weld treatment, where appropriate.
In structural hollow-section constructions, joints used are usually T, K, N and Y joints
and butt joints between hollow sections. Joints are most often welded at the workshop.
Limit values for the geometry of load-transmitting welded joints are given in standard
EN 1993-1-8 (2005) and instructions are published by CIDECT (1996). Bolted joints
are usually used when components are joined on-site. Meshed joints and the
possibilities offered by laser-beam machining have not been widely utilised in loadtransmitting
joints.
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