Specialty Blenders of Heritage Lubricants

APPLICATION INFORMATION ON CONDENSING MARINE

STEAM POWER PLANTS

The lubrication of condensing marine steam power plants is a special case.  The re-use of engine condensate as feedwater in the boiler requires a cylinder lubricant that does not form stable oil-in-water emulsions and separates readily from the condensate so it remains in the hot well and does not enter the boiler along with the feedwater.  This is called "demulsibility", or the ability to form cohesive films on the surface of water so the oil can be skimmed or absorbed without residues left in the body of water.

The primary path to the above features is the elimination of all animal fats in cylinder lubricants.  Animal fats such as the lard oil and tallow oil used in Green Velvet lubricants are intended to form stable emulsions in water and steam.  These emulsions when combined with other impurities approximate the same density as water and tend to freely disperse in a body of water.  They are very difficult to separate from condensate.  While animal fat emulsions improve the lubrication of wet (saturated steam) engine cylinders, they are very dangerous if they enter the boiler along with condensate feedwater because the natural circulation currents carry them throughout the boiler.

These emulsions circulate freely in the boiler and inevitably contact the hot heating surfaces.  The animal fats tend to stick to the heating surfaces and form a "leathery" deposit on the heating surfaces.  These deposits are very good insulators and begin to overheat the steel heating surfaces.  As the surfaces heat up the deposits begin to outgas and puff up into a thicker, "spongy" mass.  This increases the deposits' insulating effect and further overheats the steel sheets.  The result is severely burned furnace sheets that in many cases fail and rupture with disastrous results.

Historical literature recites tests that show as little as 0.001" of this "grease" coating can cause new furnaces and tubes to collapse.  In one incident the furnaces of a passenger steamer collapsed in mid-ocean primarily due to oil contamination caused by inferior cylinder lubricants applied to the piston rods and valve stems!  Numerous accounts of marine boiler failures point to animal fat generated emulsions as being far more dangerous than plain mineral oil inside steam boilers.  Straight mineral oils tend to rise to the water surface and are evident on the adjacent boiler plates in this area.  Such oil films can contribute to severe foaming, but they seldom cause the more disastrous furnace and tube collapses.

Based on the above research we never recommend compounded oils for marine power plant cylinder lubrication.  All our Green Velvet mineral steam cylinder oils are available as non-compounded lubricants on a custom blending basis.  Our Green Velvet Pin, Bearing & Journal oils are naturally animal fat free and are safe around condensing marine steam plants.  All our Green Velvet lubricants contain a long chain polymer tackifier which is extremely hydrophobic.  This helps all Green Velvet oils separate readily from water, yet these tackifiers help form a "skin" on rubbing surfaces that enhances the lubrication of these surfaces and provides a rust protection benefit after the machine is shut down.

Green Velvet non-compounded lubricants have proven their applicability to condensing steam power plants by performance.  Please contact us for further assistance or to place an order for your reciprocating steam vessel.