Are there differences in vent system design between horizontal LH2 tanks and spherical tanks regarding vent placements?

There are no differences in the process design of the vent stack since the venting requirements will follow the same sizing and pressure rating requirements regardless of vent configuration. However, vent systems often create liquid air on their exterior due to the cold venting temperatures. Since this liquid air will drip off the stack, it should be diverted such that it does not directly impinge on the outer vacuum jacket of the vessel. The jacket is often constructed of carbon steel which is not rated for the cold temperature of the liquid air, and as a result, may crack and cause loss of vessel integrity. Horizontal tanks will usually place the vent stack such that liquid dripping from the bottom of the stack will drain to the ground. This is more difficult due to the geometry of a spherical tank so the stacks must be sited and supported differently and/or a shield be placed to prevent impingement.