Steam pipes are constantly losing heat through radiation so steam continuously condenses along entire length of piping. To avoid water hammer this condensate needs to be removed by installing thermodynamic steam traps at desired locations.
Typically for saturated steam distribution lines, steam traps should be installed every 30 meters. Steam traps should also be installed at locations where there is a change in elevation of the distribution line as condensate gets accumulated at the low-lying points in the steam pipeline.
However, the traps have to be installed in a correct way for them to function properly and evacuate condensate effectively. E.g. Drain pockets must be present at intervals of 30 m to 40 m as well as at all low points in a steam pipework.