The mixing use of standing tubes of different lengths and sizes shall be adopted when erecting them such as the 3m, 4.5m and 6m tubes with different lengths. You can make an integration of them as what the scaffolding company told you when you make a purchase there.
The standing tube ends shall be connected by the sleeve couplers while the connection of the tubes at the top of the building in the top span can be in the way of overlapping fashion. The space from the connection joints of the standing tubes to the adjacent big transverse tubes shall be no more than 1/3 the height of the lift. Both of them shall not be in the same span or the same lift and the height tolerance of the adjacent joints shall be no more than 50cm.
For the overlapping method on the top, the overlapping length shall be no less than 1M and fastened by 3 swivel couplers. The distance from the edge of the end coupler coverage to the tube ends shall be no less than 10cm.