Fitting with a coating, pipeline system and use of the fitting or of the pipeline system

The invention relates to a fitting for a sealing, non-releasable pipe connection, having a main fitting body (4) for accommodating at least one pipe (14, 16) which is to be connected, and having at least one pressing sleeve (6, 8), wherein the main fitting body (4) and the pressing sleeve (6, 8) have pressing surfaces (18, 20), which are assigned to one another, wherein the main fitting body (4) has a pressing surface (22) which, in the installed state, is directed towards the pipe (14, 16) which is to be connected, and is assigned to the peripheral region of the main fitting body (4), and wherein the pressing surfaces (18, 20) assigned to one another on the main fitting body (4) and on the pressing sleeve (6, 8) are formed such that the action of pushing the pressing sleeve (6, 8) axiallyonto the main fitting body (4) gives rise to the peripheral region of the main fitting body (4) being narrowed radially. The invention is distinguished in that a coating (26) is provided on at leastone of the pressing surfac