Extra-heavy pipe must be used on blowdown lines when the steam pressure exceeds what limit?

Extra-heavy pipe is specified for use in blowdown lines in applications where the steam pressure exceeds certain limits to ensure the safety and integrity of the system. The correct answer indicates that when steam pressure exceeds 125 psi, the use of extra-heavy pipe becomes necessary.

This requirement is in place because as steam pressure increases, the risks associated with handling the steam also rise. Standard pipe may not be able to withstand the higher pressures without succumbing to the risk of failure or leaks, which could lead to catastrophic accidents or damage to the system. Extra-heavy pipe, designed to endure greater stress, provides the structural strength and durability required for safe operation at pressures above this threshold.

It's important to note that operating blowdown lines at such high pressures necessitates careful adherence to these regulations to ensure safety and fulfill code requirements, thus emphasizing the need for using appropriate materials based on steam pressure ratings.