What is the schedule of carbon steel NH3 welded pipe for sizes 1-1/2 inches and smaller?

The correct schedule for carbon steel NH3 welded pipe for sizes 1-1/2 inches and smaller is Schedule 80. This is due to the fact that the wall thickness of Schedule 80 pipe is greater compared to Schedule 40 and other schedules, which provides the necessary strength and durability for handling ammonia (NH3) under high pressure conditions.

Using a thicker walled pipe like Schedule 80 is crucial in applications involving ammonia, since it often operates at higher pressures and requires enhanced mechanical properties to withstand the corrosive nature and potential pressure fluctuations of the gas.

In contrast, Schedule 40 has a lower wall thickness and might not provide sufficient strength for high-pressure applications, while Schedule 10 is intended for lower-pressure systems and is too thin for ammonia transport. Schedule 60 is not a standard schedule for carbon steel piping and is generally less recognized in relevant codes and standards. Therefore, Schedule 80 stands out as the most appropriate choice for safely and effectively handling NH3 in smaller sizes.