The tubes are in the boiler at this point, not visible from this angle.

The end of the pressurized boiler is at the end of the shiny sheet metal jacket covering the insulation. The rough steel forward of that point is the non-pressurized smokebox, which uses changes in gas flow direction and the coarse screening at the top to remove most of the cinders from the exhaust.

The boiler contains both small diameter fire tubes, and larger diameter flues, which themselves contain the very small diameter superheater pipe bundles. The superheater pipes heat the steam well past its boiling point, drying it so that the water molecules become much more energetic, getting more power from each gallon of water.

The tubes and flues end at the front of the boiler, held by the front flue (or tube) sheet. Removing the tubes and flues requires first removing the steam pipes in the smokebox, which are present in this photo.

Similar to the boiler, the steam pipes angling down to the cylinders are rough steel castings, covered with insulation, with a shiny sheet metal protective jacket.

Later steam locomotives were extremely complex, both to increase thermodynamic efficiency, and to help crews operate the increasingly heavy controls.

The smoke box is open, but I don't see any tubes laying around. It actually looks as if the cylinder has been replaced (an upgrade?) based upon the shiny down pipe. Compare it to the engine in the background. Regarding the tubes, I had a friend who worked for Rogers Locomotive in Paterson, NJ. He said they would take the tubes out of the longer locomotives, cut off the corroded ends, and recycle them into shorter locomotives. Mr. Gannon was 103 years old when he related this story!

But, it looks like some boiler tube work is underway.