Hello, Lutfi!
Unfortunately it seems impossible to use sketches on this forum otherwise I would send sketch of clamp type I interested in. I will have to give an example.
For example, we have an existing tubular member of some structure and we need hang something up on this member without using weld. For this purposes we could use a clamp, which will consist of 2 halves of tubular flanges with inside diameter equal to existing tubular. Each half of clamp has 2 flanges with bolt holes. Toque of bolts designated to obtain necessary clamping pressure to prevent clamp from slipping.
Thank you very much for attend to my query.