Abstract: In a machine, for making corrugated paper, of the kind including hollow cylindrical rollers, a process and apparatus is provided for improved heating of the rollers. Liquefied gas is burnt within the hollow interiors of the rollers, and the rollers are heated by radiation from the resultant combustion gases. A combustion tube is fitted into the interior of each roller, and a liquefied gas jet burner is located outside each roller and includes a nozzle directed towards one end of the combustion tube. A radiator tube is provided within the roller in surrounding spaced relation to the combustion tube, forming an annular space therebetween through which auxiliary air is supplied. The radiator tube is heated primarily by radiation from the combustion tube, and transmits its heat by radiation to the roller. Means are provided for cooling each bearing of the rollers.