A retaining system for joints without utilising welds, screws or any other additional element or accessory, consisting in the making of a closing or locking mechanism, by means of a tab-slot configuration, using only the structure proper of the sections which are the object of the jointing, according to a first section (A) on which the cutting or machining that gives rise to the tabs and an embedment gap is made and a second section (B) that houses the slots and has to fit in the said embedment gap of section (A). Finally, the system is supplemented with the addition of tools that make it possible to release the system, thus making the joint demountable.