The inlet and outlet manifolds (4) are situated outside of the casing (1) and have a demountable character, such that by removing said manifolds (4), "in situ" cleaning and maintenance tasks of the tubular battery are possible, as well as the temporary closing off of any of said tubes (3) which is broken down, by closing the ends (10) thereof by means of respective caps, and the extraction of the broken down tubes, for the replacement thereof, through the side opposite to the manifolds (4) is also possible after the unwelding of the two connections and as a result of the existence of special crossbars (13-14) which, suitably fixing the tubes (13) inside the framework (16), are shaped and positioned so as to not constitute stops interfering in said transverse shifting of the tubes.