Hello mariog

I suppose the difference would vary. I did an exercise with the formula for computing tank wall thickness comparing Metric with USCU. The difference is compounded by the fact that API uses soft conversions, and that the allowable stresses (Sd) have different values in the USCU and metric units in the material tables.

I suppose the simplest solution to all these metric-USCU problems is for America to dump the Imperial system, and align themselves with the rest of the world.

It seems counterproductive to me to have mass and weight in the same units (lb). There is no such confusion in the metric system.