Avoid lagging for personnel protection if at all possible. You will be buying a great deal of corrosion problems for no process benefit. The standard to look at for insulation is a Dutch one: CINI Manual Insulation For Industries
BChoate
Under insulation corrosion can become and issue when equipment is insulated for personnel protection. Typically, personnel protection considers keeping the surface temperaure below 150 F; as low as economically possible, perhaps 130 F. Insulation requirements are calculated from a heat transfer basis (conduction and radiation)based on the process temperature, the pipe thickness, the insulation type, and aluminum covering if needed. A link giving some information is
Many times, if the temperature is high enough to warrant personnel protection, there are also process benefits. If a fluid is being heated or cooled, then the heat transfer fluid (HTF) temperature, without losses to the environment, affords a lower HTF flow rate. Certainly, if cooling is substantially below atmospheric dew point, insulation and sealing prevents condensation on the equipment. Safety is an important issue. I would like to think that none of us would leave an exchanger at 400 F bare and open to contact with personnel. If under insulation corrosion is an issue, the equipment should be primed with an appropriate thickness of a suitable primer. In some of my assignments, stainless steel was primed prior to insulation.
Bill C.
