The Valve Surface Area Factor in AutoPIPE is used to calculate both the valve insulation weight and the buoyant force for submerged valves. For standard valves, this value is typically obtained automatically from the valve database, while for non-standard valves it may need to be entered manually. 

Regarding insulation weight, AutoPIPE uses the Surface Area Factor as a multiplier on the insulation weight of an equivalent length of adjacent pipe. Therefore, the calculation is effectively:

Valve Insulation Weight per Unit Length = Valve Surface Area Factor × Pipe Insulation Weight per Unit Length

The total insulation weight applied to the valve is then based on this adjusted unit weight over the valve's face-to-face length. As a result, a valve with a Surface Area Factor greater than 1.0 will attract more insulation weight than an equivalent length of straight pipe, reflecting its larger external surface area.

The same factor is also used when calculating buoyancy for submerged valves. For example, if the equivalent pipe buoyancy force is 1000 lb and the Surface Area Factor is 1.5, AutoPIPE will apply a buoyancy force of 1500 lb to the valve.



The surface area factor does not appear to affect the hydrodynamic loading. Hydrodynamic forces simply consider the OD of the PIPEID, plus any marine growth input in the wave load dialog.