Tube Connectors. A great idea from off-road and dirt track racing. Several sizes available. Use these clamps to make sections of steel tubing easily removeable.
Here is a picture of a tube clamp welded into the structure of a racecar.
Here is Silent Mike McCooey showing a removeable stretch of tubing on a racecar.
Here is that tube removed, by taking out 4 screws. Notice that now the radiator and whol;e engine and transmission can come easily right out the front of this racecar. Think about accessing cameras or equipment inside a tube structure like a stunt car roll cage or tube framed piece of equipment like a specialized camera car. Save valuable time on equipment changeovers while the shooting company waits and assistant directors ask "How Long??"