All the materials used in the construction shall be approved as qualified. For the steel tubes and couplers failed to meet the requirements, shall be re-tested and inspected according to actual technical property.
All the couplers including the pressed sleeve coupler shall be indentified according to the requirements below:
The couplers specification shall be matching to the OD of the steel tubes. The torque force of the bolts shall be no smaller than 40NM no bigger than 64NM. The major connection joints o the standing tubes shall be used for fastening and fixing the transverse and longitudinal tubes.
The splitting space of the two adjacent joints every one standing tube alongside the height in one lift shall be no smaller than 500mm and the each connection joints center shall be no bigger than 1/3 of the lift space away from the main joints. The double standing tubes will be used in some parts of this project and the sub standing tubes shall be 12m long and the main standing tubes and the sub one shall be crossed set. For the two in one lift, the fastening work shall be done by the second swivel couplers.