What type of fittings are specifically designed for water columns operating above 350 PSI?

Fittings designed for water columns operating above 350 PSI must possess specific structural integrity and pressure ratings. Steel fittings are the preferred choice in such high-pressure applications due to their strength and durability. Steel can withstand significant force without deforming or failing, making it ideal for the robust environments typically found in steam systems operating at elevated pressures.

In contrast, brass fittings, while useful in some lower-pressure applications, do not have the same level of strength as steel and can be prone to failure under extreme conditions. Plastic fittings are not suitable at such high pressures since they can crack and degrade, losing their integrity and leading to potential leaks. Copper fittings, while they also have good pressure handling capabilities, do not match the strength and performance thresholds that steel provides at these elevated pressures. Therefore, for safety and reliability in high-pressure environments, steel fittings are the correct choice.