Most aircraft hydraulic flexible pipes are manufactured from Aeroquip high pressure hose and for hydraulic systems that operate at 3000 psi, the rig pressure test is 4500 psi. Same applies to the rigid pipes. Someone I know who attended a hose manufacturing course saw a demonstration in which a pipe was tested to destruction. It failed at 21000 psi. So your brake lines are pretty tough!
I've found that most brake seal leaks tend to occur in cold weather, irrespective of whether the parking brake has been set.