A value of 14 MPa for FRP allowable hoop stress seems low indeed. I would expect a value of approx 60-70 MPa or something like that. However you're bound to the information given by the pipe vendor as allowable stress depends on a lot of things, like for example winding angle and base materials used. If the pipe is made for non-pressurized usage the winding angle may be far of from 55 degrees and may provide much axial strength and less hoop strength.