When I took my RV back to the factory for some warranty work, they did a pressure test on the plumbing at 80 psi. 55 psi shouldn't be a problem.
Class C, 2004/5 Four Winds Dutchman Express 28A, Chevy chassis
2010 Subaru Impreza Sedan
Camped in 45 states, 7 Provinces and 1 Territory