What material is recommended for the construction of the Hartford Loop in a one pipe up gravity steam system to avoid water hammer noise?

The Hartford Loop in a one-pipe gravity steam system is a critical component designed to prevent water hammer, which is the noise and vibration caused by steam traps and condensate returning to the boiler. The recommended material for constructing the Hartford Loop is a closed nipple.

Closed nipples are usually made of iron or steel and provide a seamless and sturdy connection between different sections of the piping. Their solid construction helps absorb any vibration and sound that might occur due to the rapid changes in pressure and temperature within a steam system. This robust material allows for better performance in providing a reliable, leak-free seal in high-temperature and high-pressure environments, which is essential for maintaining an efficient steam system without the disruptive noise associated with water hammer.

Other materials, while potentially usable, may not provide the same level of durability or sound dampening. For instance, steel pipe and brass fittings may not be as effective in specifically addressing the issue of noise created by condensate flow. PVC, although lightweight and resistant to corrosion, is not suitable for high-temperature steam applications and can fail under those conditions. Thus, the use of a closed nipple ensures both functional integrity and noise reduction in the Hartford Loop configuration.