Other uses of black steel pipes include gas distribution inside and outside homes, water wells and sewage systems. However, black steel pipes are never used for transporting potable water due to the fact that they tend to corrode in water and mineral of the pipe will dissolve into the water and clog the line as well.
The principle involved with boilers is a process known as ‘deaeration’ whereby the oxygen in the water is liberated - usually upon heating- and is vented to atmosphere. So, for circulating heated water systems what little oxygen there is gets eliminated. Whatever makeup is required due to leakage, etc. is small enough to be of little or no concern. In medium-sized commercial boilers, oxygen is often controlled through chemical addition.
In the case of large, high pressure, industrial and utility steam-producing boilers, the makeup water first passes through a “deaerator” which liberates oxygen using steam and vents it to atmosphere. (The small wisp of steam you often see exiting the top of a large boiler plant is the deaerator vent). After that the water in the boiler is usually treated with an oxygen scavanging chemical to remove the final traces. Otherwise the carbon steel boiler tube woudl quickly fail due to corrosion
With respect to the question about foul odor in water, I believe that is caused by sulfur compounds that naturally occur in the region’s ground water and, as far as I know, has little or nothing to do with the type of pipe used.
