Generally speaking, all the galvanized steel tubes, no matter they are hot dipped or cold dipped, cannot be welded to be welded steel tubes.
However, everything has an exception. For the galvanized steel tubes with an OD of more than 100mm, the connection shall be flannel or coupler and the joints between the galvanized scaffolding tube and the flannel shall be processed with a second time of galvanization.
The welded steel tubes, especially the stainless ones, can be widely used in the steel concrete projects. The reason is that the steel tubes can be used to improve the concrete strength and its capacity in fighting against the harsh marine environment when the stainless steel concrete is used on the bridges of many coastal buildings, such as the Coosbay Bridge, which has a higher requirement on the anti-erosion degree and the seismic-proof ratio.
When compared with normal carbon steels, the stainless welded steel products have better comprehensive properties and longer working lives even though they are with higher costs at the first few phases.