Force applied to a 90 degree elbow by hydraulic flow

I have a question about forces applied to a 90 degree elbow.

Essentially we have a 90 degree pipe bend used to redirect discharge from a water system, which can discharge high volumes and pressures unexpectedly. I would like to assess the forces acting on the pipe bend as horizontal and vertical components of the force vector applied to the 90 degree elbow, to see if the weighting & restraints we have applied to the bend are sufficient.

Are these: http://www.engineeringtoolbox.com/forces-pipe-bends-d_968.html the correct formulas to assess this?

Any advice or tips you can provide would be appreciated, thanks in advance.

The formulas you linked to assume pressure $p$ to be the same at entry and outlet (an acceptable approximation in most cases).
In the page I linked too, set $p_1A_1=p_2A_2$ (which applies to your problem) and thus also $V_1=V_2$ and the conclusions are then reduced to the formulas given by your link.