Can we have condensate in a superheated steam line?. I run a 300 psi superheated steam line that was sufficiently trapped and partly insulated. One of my service guys shut all the traps and the next day the whole line was full of water. Then somebody told my operator that the water was not as a result of shutting the traps, that there can be no condensate in a superheated steam line. What do you guys say?

I have worked a few years in the field and believe me there are no "ideal" conditions out there. The safetyvalves must be installed and fully functional or you could have catastrophic results if the line encounters adverse conditions such as an underground steam supply that becomes submerged due to a penetrated rickwell or tunnel wall (how could that happen?. Make sure that those traps are functioning at all times.

As long as there is air, oxygen and other dissolved gases in feedwater, there will be pressure-loss-induced condensate, whether the steam is saturated or superheated.  The feedwater will always contain air. It can also contain bicarbonates and carbonate alkalinities, which oxidize to carbon dioxide at elevated temperatures. The oxygen and carbon dioxide together combine to produce acidic carbonization that has a corrosive effect.  Deaeration and pretreatment of the feedwater does not remove all the air, some of them are carried over to the steam. This is a malignant fact associated with steam generation.

In gas mixtures or multiphase flows, each gas assumes a part of the total volume or pressure. This is referred to as the law of partial pressures. The partial pressure of each constituent gas depends upon its proportion of the total pressure of the mixture.  This is true regardless of whether the gas is ideal or Van der Waal.

Consider a 100 psi line consisting of 80% quality steam and say 20% air, the total steam pressure would be 80 psi and the total air pressure 20 psi.  Consequently, the line would have 80 psi steam in a 100 psi line at a temperature of 312 degrees instead of 327 degrees at 100 psi, a difference of 15 degrees between the two pressures.  In addition, there will a change in BTU