Pressure Hose (Power Steering Pump)

I replaced my power steering pump about 2 months ago....everything was fine until a few days ago. I hadn't driven my car for a few days, drove it to work and it started making the typical loud whining noise....checked the reservoir and it was basically empty. Short story shorter......the pressure hose fitting going into the pump was loose. I did some research and learned that there is supposed to be an o-ring that seals the pressure hose fitting to the pump?



When I replaced the old pump, there was no o-ring. It's an 03' 325i, I bought it 5 months ago...the old pump was a bosch. I'm assuming that's not the original power steering pump. ?



My question....is there supposed to be an o-ring and is that the possible reason why the fitting has loosened up? Also...is there a torque spec for that bolt?



Any info is appreciated