Pipeline Dew Point

The dewpoint temperature is the temperature at which the air can now longer hold all of its water vapor, and some of the water vapor must condense into liquid water. At 100% relative humidity, the dewpoint temperature and real temperature are the same, and clouds or fog can begin to form. While relative humidity is a relative measure of how humid it is, the dewpoint temperature is an absolute measure of how much water vapor is in the air (how humid it is). In very warm, humid conditions, the dewpoint temperature can reach 75 to 77 degrees F, but rarely exceeds 80 degrees.


Regards Woody

You never want water to collect in your pipeline. Keeping it at a temp that does not allow condensation prevents water from accumulating. I am not so certain about natural gas, but fuel pipelines are often packed with an inert gas for two reasons. One is to eliminate the chance of condensation, the other is because when fuel is introduced to the pipe, there could be sloshing and agitation of the fuel which creates more vapors and increases static charge. Fuel is inherently dry, and dry moving fluids or powders tend to build up a static charge, if the pipe was filled with air (22% oxygen) you could get a flammable mixture of air and fuel vapors. If the static charge in the fuel creates a spark you get a fire.

I think that is more than you asked, but it is related.

Drew

"In very warm, humid conditions, the dewpoint temperature can reach 75 to 77 degrees F, but rarely exceeds 80 degrees."

In Southeast Asia (equatorial climate) it always exceed 80deg F, especially in Malaysia, Indonesia & Singapore.

But he is saying below dew point and not above. I am not sure it is always possible either.

Well, (no pun intended), good answer.

Liquid water is very corrosive to many engineering materials. At temperatures well above the dewpoint, the water is present as gas or vapor. Below the dewpoint it condenses on surfaces as liquid and remains liquid until it either evaporates or freezes. Two conventional methods for reducing water vapor concentration include, 1) heating the vapor and sweeping it out with a dry gas, and 2) using a desiccant to trap the water molecules. Desiccants are to water vapor as a sponge is to liquid water. When the sponge becomes saturated it must be either discarded or wrung out.