The frame scaffolding are firstly used in the frame projects in the subway and express high way. With the wide spread application of the frame scaffolding around the country, its popularity and usage have been widely acknowledged and more and more construction companies change to use such scaffolding products. In 1956 Japan issued a JIS standard about this frame scaffolding and in 1963 Chinese provinces also made some regulations and requirements on this kind of scaffolding. The main joints of the movable frame scaffolding shall be set with a transverse tube and fastened by right angle couplers. The main joints including the coupling joints among the standing tubes, the longitudinal tubes and the transverse tubes. The center distance between the right angle couplers at the main joints shall be no more than 150mm.
In the double line scaffolding system, the protruding length of the transverse tubes which is close to the wall shall be no more than 0.4 times the distance between transverse tubes lower than 500mm. The distance between the transverse tubes on the working platform while not at the main joint place shall be determined according to the requirements and real needs of the planks.