The longitudinal horizontal tubes shall be set inside the standing tubes with a length shorter than 3 spans. The connection of the longitudinal horizontal tubes shall use the sleeve couplers and the connection requirements are listed as follows: when use the pressed steel planks, the wood scaffolding step board, the bamboo scaffolds planks, the longitudinal horizontal tubes shall be used as the base
plate of the transverse horizontal tubes and fixed on the standing tubes with the right angle couplers.
If use the bamboo scaffolding plnaks, the longitudinal horizontal tubes shall be fastened to the transverse horizontal tubes with the right angle couplers and set with equal space between them. While the space shall be no more than 400mm.
For the external frames, the putlog shall be set according to the crossing point of the standing tubes and the ledgers and the two ends of the putlog shall be fixed to the standing tubes to form a space structure so the load can bore by the scaffolding frames as a whole.