Shipping

Shipping, Storage, Handling

Prefabricated tension elements and especially cables are subject to specific requirements which have to be strictly adhered to during production, shipping and storage.

Shipping

When shipping cables, it is essential to make sure that the cables do not suffer any damage during transportation since this would lead to both impaired corrosion protection and impaired visual appearance. Cables are shipped in wooden crates, coiled or uncoiled, in rings or rolled up on reels.

For the loading process, the cables must be fastened in an appropriate way – either directly on the cable or on appropriate load bearing packing equipment:

• If the packing equipment is load bearing, careful handling of it – i.e. avoiding damage to it – will exclude damage to the cables.

• If the cables are coiled into rings and stored lying on squared timber, they have to be fastened with at least three Polytex slings which are offset to one another at an angle of 120 º. Chains, wire rope slings and similar load bearing equipment must not be fastened to the tension elements.

For sea freight regulations as to seaworthy packing have to be strictly adhered to.

Storage

Galvanized cables and components should be stored in dry and clean conditions – appropriate ventilation must be guaranteed. The following conditions must be adhered to:

• Components must be protected from accidental damage on the building site i.e. vehicles bumping into the cables, etc.

• Surrounding air must be free of sanding or cutting dust of corrosive steels

• Cables must not be stored lying in water

• Components must be protected from uncoiling, slipping and twisting

Handling

Competent handling of the cables at any given time during the installation process is absolutely essential. Depending on the form in which they are delivered, the cables are either directly taken up for installation or have to be coiled or uncoiled beforehand. While the cables are handled, any damage to them must be avoided. Warming, sanding or cutting of prefabricated tension elements on the construction site is inadmissible.

Important Handling Recommendations:

• For cables that are delivered uncoiled in wooden crates or fastened to a wooden board:
  The cables are connected directly out of the transport facility and brought to the installation site. When the cables are taken up, it is essential that they are not bent too much. The maximum bending radius must not fall short of 15x cable diameter.

• For cables delivered on reels:
  The cables are either directly unreeled or the reel is taken up by an unreel stand and the cable is unreeled subsequently. The bending radius must not fall short of 15x cable diameter here either

• For cables delivered in cable rings:
  A turn table is used for uncoiling. For the uncoiling process, the cable is drawn from the turn table, at the same time the turn table is driven in circumferential direction. Pulling the cable off the turn table with a crane is possible, however, bending radii (larger than 15x cable diameter) must be strictly adhered to.

If cables are installed horizontally struts or spreader beams are to be used.

Laying out VVS-cables with a mobile unreel stand – here a tensioning ring, National Stadium Main Bowl Complex, Abuja.

Installation of cables

During installation the cables must not be dragged on the ground or over feather edges. In practice specifically developed reel stations have proved highly efficient for the movement of cables over even surfaces.

IMPORTANT NOTE!
Cables must not be twisted around their rotation axis when they are installed into the structure. Twisting around their longitudinal axis can considerably reduce the load bearing capacity of a cable.

Installation of the ring cable connector is always carried out manually – here inserting and aligning of connectors, National Stadium Main Bowl Complex, Abuja.

Tensioning of cables

Tensioning is carried out either directly via the cable or via the mounting parts on the terminals. If the cables are used directly for tensioning, specifically developed clamps will be used. Clamp forces are defined via the pre specified torque of the clamp botts. To avoid damage of individual wires of the cables, pre specified clamp forces must not be exceeded.

As a rule, documentation of the tensioning forces is required. Measurements are taken by a cable tension metre with a cable measure curve, which is drawn up during the final planning, or by a hydraulic tensioning device.

After tensioning the cables, the seizing wires, which prevent escaping of the wires, must strictly be removed.