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If any cracks or breaks on the main chord occur or if it is rolled more than 10% of the original diameter the truss should be marked and taken out of
service. Also, the end section of the truss, where the truss is connected, should not be in such a condition that it can only be connected with much higher
force.
Further signs of a discard condition are:
•
Any scratches, cuts etc on the main chord that causes reduction of the cross-sectional area of the main chord over 10%.
•
Any indentations that are more than 1mm deep and 10mm long.
•
Any holes appearing after use of the truss.
•
Any deformation from the original shape to an oval shape or indentation by more than 10%.
Any brace (diagonal, cross or end brace) is broken or is not there, the truss is not usable anymore.
Further signs of a discard condition are:
•
Any scratches, cuts etc on the brace that causes reduction of the cross-sectional area of the brace over 10%.
•
Any indentations that are more than 0,5mm deep and 10mm long.
•
Any holes appearing after use of the truss.
•
Any deformation from the original shape to an oval shape or indentation by more than 10%.
Discard conditions:
•
Any cracks or breaks on the welding seam between the connector and main pipe.
•
Oval signs of wear higher than 10% of the original diameter in the drill holes.
•
More than 2degreed rotational displacement of the drill holes in a connector or 2
adjoining connectors.
•
More than 5degrees deflection of the main chords with the connector, make the truss
hard to assemble.
•
Any signs of use causing reduction of the cross-sectional area of the connector higher
10%.
•
Any deformations in the main chord next to the connector welds.
•
Too high tensile force may cause domination of the main chord by the welds.
•
Buckling caused by overloading with excessive force.
•
Any damage, scratch or cut in dentation more than 2mm deep and 10mm long.
•
Corrosion
Conical spigots are used very frequently. If any deformations occur they this indicates massive overload. Such bolts cannot be used anymore.
Other conditions for discard:
•
Any cuts indentations, scratches on the conical spigot surface.
•
Any protruding, pointed or sharp edges on the narrow end of the conical spigot.
•
Deformation cause by hammering.
•
Corrosion.
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