Hose bends. Rigid pipe does not.
Two kinds of line carry concrete away from a pump, and people use the same word for both. Hose is flexible. It bends around the corner of a house, gets carried through a gate, and comes apart and goes back together as the route asks. Rigid pipe holds its shape and its position once it is set, which makes it a tool for a straight, fixed run rather than something a man steers with his hands.
That difference is the whole reason a house pour runs on hose. The path from a spot where a ready-mix truck can genuinely park to the back corner of a lot is almost never straight, and hose is what lets the line follow somebody walking instead of following a drawing. Our own trailer carries line in 2.5 inch and 3 inch, and the layout gets built out of sections on the morning it is needed.
The inch figure is the bore, not the outside of the hose
When a crew says two and a half inch line, the number is the inside of the hose. The wall sits outside that measurement, because the wall is there to hold pressure in rather than to carry material. A section is thicker in the hand than the figure suggests, which surprises anybody whose mental picture came from a garden hose.
The bore is the number that matters to the concrete, because everything suspended in the load has to make that trip with room around it. A stone too large for the opening it is riding through will catch against another one, and the rest of the load stacks up behind the pair of them. That is the plain reason the plant gets told which line size is coming when the aggregate for a pumped load is picked.
Between the two sizes we carry, the larger bore moves more volume against less friction and the smaller one is lighter to steer by hand. Which one fits a job comes out of the route, and the route gets walked before anybody decides.
Full hose stays where it was laid
An empty section is something two people pick up and walk with. With a load in it, that same section is heavy, and nobody is repositioning it while concrete is moving. That is the plain reason a route gets settled, run and primed before the first truck backs in, rather than sorted out with a loaded mixer sitting on the clock.
- Sections clamp together, so the length is built to the site instead of being a fixed reach
- Bends stay long and sweeping, since a sharp kink is where a load is most likely to pack
- Whatever the line crosses, it sits on for as long as the pour runs, so crossings get chosen on purpose and agreed with you
- When the last yard is placed the line has to be cleared and washed out, in a spot picked before anything started