Can any one guide me how to calculate Horizontal saftey Valve Reaction Force in Boiler Steam Line Asper Mandetory AppendixII you can only calculate Vertical force of saftey relief valve not horizontal.

If I look at API its says 2/3 of Horizontal force is vertical

I have received V-hr=20440N V-vertical=3755N

Can any one Please tell me how to calculate horizontal force .

om123,

It depends on the geometry of the discharge pipe of the safety relief valve. The ASME B31.1 Appendix II Fig II-2-1 shows a typical safety relief valve with 90 elbow on the side outlet of the relief valve. The horizontal loads are balanced from the horizontal pressure areas. Net horizontal load is zero in the steady relief flow condition. There are unequal pressure areas in the vertical direction that result in the vertical load.

The B31.1 Appendix II Figure II-6-1 (a) shows a 45 degree elbow on the side outlet of the relief valve. Since there are horizontal and vertical load vector components the Fig.(a) geometry, it has both horizontal and vertical loads on the relief valve. The geometry is arranged to result in nearly zero moment loads at the relief valve root connection.

If i have a condition where as per Fig- II-2-1 appendix II of 31.1 and after elbow a pipe piece of of larger size towards silencer only sileencer is supported by at top b ut the pipe whole vertical load is comes on the elbow and transfer to the below pipe through a +Z(Vertical restraint) But my boiler supplier has provided me a horizontal force which is very high.

As per your observation there should be no horizontal force.

I think we have to refer API 520 for Relief valve loads.

om123,

You mention vertical load from elbow to pipe is transferred thru a +Z vertical restraint.

The +Z vertical direction is probably from a CAD convention for +Z vertical. I am old school 2D CAD where +Y is vertical.

You might need to confirm that the boiler supplier is using +Y or +Z for the vertical (or horizontal) load.

The relief side outlet connection would see a horizontal load, if a run of straight pipe was attached to the relief valve. This would be like the outlet pipe was directed to outside of building by a flat horizontal pipe run. If the boiler supplier is providing the relief valve, but no outlet piping, then his horizontal load on the relief valve is correct for no elbow (straight pipe) connected to the relief valve side outlet.