I don't believe high pressure steam systems are your average plumbing system Michael. That's why the union crews that lack experience are the first to 'run for the hills' when hammering starts. What if the system was designed and built to withstand 300#psi operation, and the 100# safety relief valve had to be temporary taken out of service so the system (as per contract) could be tested and proven to function at 75% or better of the design capacity. And during the initial start up for the testing, some material debris (common to new construction) caused several key traps to fail, which caused condensation to build in the steam main which caused the main to start hammering. And thanks to the hammering, they determined faulty components of the system, corrected those problems and reinstalled the relief valve prior to regular operation of the system. Would you still be pushing for $882,000.00 in fines?