After installation, steel pipework can contain steel swarf, millscale, grease, hemp etc. Unless these items are removed, they can cause problems later. A chemical clean (“precommission clean”) is carried out using a chemical cleaner which can contain detergent, dispersant, de-greaser etc.
After cleaning, a corrosion inhibitor should be added and afterwards monitored regularly.
If there is a chilled water system as well, it may be necessary to add antifreeze to avoid frost damage in cold weather.