US2415353A - Rust preventing turbine oil - Google Patents

Description

Patented Feb. 4, 1947 TE FlCE RUST PREVENTING TURBINE H4 No Drawing. Application March 15, 1944,

Serial No. 526,654

3 Claims.

This invention relates to lubricating oil compositions and more particularly to a mineral lubricating oil which resists rust formation on iron and steel surfaces in the presence of water and is especially free from the tendency to form emulsions in the presence of water.

Oils used for the lubrication of steam turbines and other machinery which is much in contact with water may successfully be treated with cer tain rust preventing agents, such as metallic naphthenates, metallic sulfonates and the like which have the property of causing the metal surface to be preferentially wetted with the oil instead of water, thus preventing or substantially reducing the actual contact of the water with the metal surface and the ensuing rust formation. An objectionable feature usually resulting from the use of such compounds is the tendency of the additives to cause the formation of an emulsion of the oil with the water, and this is especially objectionable in the lubrication of steam turbines. It is highly desirable, therefore, to prepare lubricating oil compositions which are free from the emulsion-forming tendency and which at the same time offer substantial resistance to rust formation in the presence of water. In the case of marine turbines the oil should also prevent rusting in the presence of sea water.

The emulsions which may be formed when the blended lubricating oils are brought into contact with water are of two types, depending upon the type of corrosion resisting additive which is used. Metallic soaps or salts containing alkali metals tend to promote the formation of oil-in-water emulsions, while soaps or salts of the polyvalent metals promote water-in-oil emulsions. It has been found, in accordance with the present invention, that when, in addition to the corrosion preventing compounds, an additional compound is added to the lubricating oil which is of the opposite emulsion-forming type, it is possible, by properly adjusting the relative quantities of the two additives, to reduce the emulsion-forming property of the oil blend to a minimum and to produce thereby a blend which is practically non emulsifying. That is, if the corrosion resisting agent is of the type which tends to form oil-inwater emulsions, the second additive should be of the type which tends to form water-in-oil emulsions. Both of these additives may be of a corrrosion resisting type, and the invention is preferably practiced by using a combination of an alkali metal mahogany sulfonate and a polyvalent metal naphthenate as the rust resisting component of the lubricating oil.

When a turbine oil is to be prepared, the lubricating oil base is preferably a highly refined oil of from 50 to 1,500 seconds viscosity (Saybolt) at F. However, the invention is not limited to the preparation of turbine oils, but is applicable to lubricants for the bearings of machinery which is much in contact with water, such as in paper mills and refrigerating equipment, as well as to crankcase lubricants, steam engine lubricants, hydraulic fluids, textile oils, cutting oils and insulating oils, and in general in all cases where a mineral oil is used under conditions in which it may pick up or absorb small amounts of water from atmospheric condensation or from other sources of contamination.

The additives which promote oil-in-water emulsions and possess rust resisting properties include particularly the alkali mahogany sulfonates. Rust resisting additives which tend to form we.- ter-in-oil emulsions include especially the naphthenates of polyvalent metals, such as calcium, Zll'lC, lead, copper, aluminum, beryllium and related metals. When a rust preventing additive of each of the two types is added to the lubricating oil, the quantity of each salt is preferably from 0.01% to 1.0% by weight, based on the 111- bricating oil.

The following is an example of the desirable properties which may be obtained by combining two difierent types of metallic soaps in an oil blend in accordance with the present invention.

Example Several blends of sodium mahognany sulfonates and zinc naphthenate in difierent proportions in a highly refined mineral oil of approximately 390 seconds viscosity Saybolt at 100 F., and blends containing combinations of these additives, were prepared and subjected to a corrosion test and an emulsion test which will be described below.

The corrosion test employed was the test known as the Navy 2190T Salt Water Corrosion Test (Specification 14-13-15 (INT), F-C(3), March 1, 1943) which consisted in suspending a polished steel specimen in a mixture of the oil under test with 10% by volume of synthetic sea water containing 11 grams of MgC12.6I-I2O, 1.2 grams CaClz, 4.0 grams NazSOa and 25 grams NaCl per liter, and agitating for as hours at 140 F.

The emulsion test employed was the Navy Emulsion Test (Federal Specification VV-L-791b, Method 320.13, February 19, 1942), which consisted in agitating 40 cc. of the oil with 40 cc. of distilled water at F. to obtain thorough mixing, followed by settling at 130 F. for 30 minutes and reading the volume of emulsion remaining after this time, 3 cc. or less being considered satisfactory. This procedure was repeated using 1% NaCl solution in place of the distilled water.

The results of these tests as applied to the various blends prepared are shown in the following table:

Navy emulsion test (cc. emulsion of- Corro(sdion ter hr.) q test esample gree of rusting) With dis- With 1% tilled NaCl water solution Mineral oil Heavy 0 Mineral oil+0.02% zinc naphdo .1 0 0 thenate. Mineral oi1+0.05% zinc naph Light 0 0 thenate. Mineral oil-{010% zinc naph- Traee 0 0 thenate. Mineral oil+0.50% zinc naphdo H 28 0 thenatel Mineral oil+0.02% sodium ma- Heavy l l hogany sulfonate. Mineral oil+0.05% sodium ma- Trace... 37 0 hogany sulfonate. Mineral oil+0.l0% sodium ma- Nil 34 3 hogany sulfonate. Mineral oil+0.05% zinc naph- Trace"... 2 0

thenatc+0.02% sodium mahogany sulfonate. Mineral oil+0i05% zine napth- Nil V 0 thenate+0.05% sodium mahogany sulfonate.

The above data show that sea water rusting cannot be stopped by the use of Zinc naphthenate alone in concentrations up to 0.5%, and that when as much as 0.5% zinc naphthenate is used the blend is poor in emulsion-forming properties. With sodium mahogany sulfonate alone, sea water rusting can be stopped by the use of 0.1% in the oil, but the emulsion-forming properties are again very poor. The use of 0.05% sodium mahogany sulfonate was not sufiicient to prevent rusting, and even this quantity produced a large amount of emulsion. The use of the combination of the metallic soaps gave much better results, and the combination of 0.05% of each of the two soaps gave the best results among the blends tested, as the corrosion was entirely prevented and only a very small amount of emulsion was formed in the distilled water test and none was formed in the 1% NaCl test.

The oil compositions of the present invention may contain other ingredients in addition to the corrosion resisting metallic salts. Thus the oils may contain sludge dispersers, thickeners, viscosity index improvers, oiliness agents, antioxidants, dyes, etc.

This invention is not to be considered as limited by any of the examples mentioned or described herein, which are given for illustrative purposes only, but is to be limited solely by the terms of the appended claims.

We claim:

1. A mineral lubricating oil containing dissolved therein about 0.01% to about 1.0% of an alkali metal mahogany sulfonate and about 0.01% to about 1.0% of a polyvalent metal naphthenate, the ratio of the quantities of the two additives being adjusted so that the oil blend exhibits substantially no emulsifying tendency in the presence of water.

2. A mineral lubricating oil containing dis solved therein about 0.05% of sodium mahogany sulfonate and about 0.05% of zinc naphthenate.

3. A mineral lubricating oil composition acaccording to claim 1 in which the polyvalent metal naphthenate is zinc naphthenate.

ROBERT K. JOHNSTON. JONES I. WASSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,888,974 Becker Nov. 29, 1932 2,109,779 Morway Mar. 1, 1938 2,111,907 Zimmer Mar. 22, 1938 2,214,634 Dombrow Sept. 10, 1940 2,221,162 Ashburn Nov. 12, 1940 2,308,116 Silverman Jan. 12, 1943