What pressure and what fittings?
If you look at diesels, they are up there!
http://www.dieselbombers.com/dodge-diesel-tech-articles/6805-5-9l-injectors-tech-specs.html

Fuel Injector " Pop Off " Pressure
31,026 kPa (310 bars) or (4500 psi +/- 250 psi)
Fuel Injector Leak Down Pressure
App 20 bars (291 psi) lower than pop pressure

All tube fittings are dry!