Originally Posted by smd4
"Boilers are tested at four times the maximum allowable working pressure....."
Bull!
As one who was a journeyman Boilermaker, having completed my apprenticeship at Puget Sound Naval Shipyard, and had a qualification (Test Director) to hydrostatically test them- (meaning my name went on the bottom of the test forum)
Every 5 years a boiler is required to have a strength test at 150%. NOTHING higher.
If it was relatively minor repair or maintenance, then 125%.