Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/02—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in air or gases by adding vapour phase inhibitors

Definitions

• the invention relates to the inhibition that is to say the prevention or reduction, of the corrosion of iron and steel, especially the corrosion of iron and steel which comes into contact either continuously or intermittently with water containing chlorine ions.
• iron and steel is to be understood to include alloys of iron.
• the invention is particularly important with respect to the metal surface of cargo tanks in marinetankers.
• the walls of the tanks are almost continually exposed to corrosive influences. Petroleum or petroleum products transported by these tankers may cause corrosion on account of the great solubility of oxygen in these products and the small amount of water which is usually present in such a cargo.
• Serious corrosion is also caused by the periodical cleaning of the tanks which, in order to save time, is usually done at sea and consequently with sea-water.
• sea-water is often heated to 80 C. to 90 C. and then sprayed until pressure against the walls in order to remove as much rust as possible together with the oil residues.
• the tank is empty the walls are corroded by the atmosphere, especially at sea.
• inhibitors When treating the Walls of the cargo tanks with corrosion-inhibiting materials, known as inhibitors, great care should be exercised in the choiceof the inhibitor. These materials cause turbidity or haze in the oil products transported even when present in small concentrations, as they promote the emulsification of water in the oil phase. Other inhibitors are soluble in oil and this is also undesirable. Moreover, it has been found that the effect of many proposed inhibitors is insufficient for the present purpose.
• the maximum effect is obtained by means of a solution containing 4-6 parts by weight of alkali metal nitrite or calcium nitrite to 3-5" parts by weight of alkali metal acetate to 34 parts by weight of alkanolamine. Outside the extreme limits specified there is a marked reduction in the corrosion-inhibiting effect.
• the preferred alkali metal nitrite used is sodium nitrite and the preferred alkali metal acetate is sodium acetate, while the prefererd alkanolamine is trior di-ethanolamine or a mixture of water-soluble alkanolamines.
• the surfaces to be protected may be treated with the above solutions according to any technique known in the art. Fairly large surfaces, for example, the walls of the cargo tanks in tankers may be sprayed with the solution. This treatment may be carried out at normal temperature, i.e. the ambient temperature, but if desired, also at elevated temperature, for example, 40 C.50 C. No other substances, for example, various phosphates, which are found in inhibitor solutions need be incorporated in the solution. The presence of chlorine ions in the solution does not neutralize the corrosion-inhibiting effect.
• the sand-blasted strips were immersed in synthetic sea-water for four half-hourly intervals spread over one day during two days. They were then suspended above synthetic sea-water for two days and then treated in the following way:
• 29th day as for 1st day, etc.
• treatment schedule is as follows:
• the method according to the invention has a number of considerable advantages over the methods of treatment of iron and steel with corrosion-inhibiting materials which have hitherto been known.
• the present inhibitor is comparatively inexpensive and owing to the good solubility concentrated. solutions may be prepared which is advantageous in connection with transport and storage.
• the solubility at low temperature is excellent so that there is scarcely any risk of crystallization.
• the solubility in hydrocarbons is also extremely low.
• the inhibitor has not been found to have any effect on the fuel properties of the fuel transported in treated cargo tanks.
• a corrosion inhibiting process for ferrous metal cargo compartments of a sea-going oil tanker which comprises: coating the metal inner surface of said compartment containing residual amounts of refined petroleum products with an aqueous concentrate containing 3-7 parts by weight of sodium nitrite, 2-6 parts by weight sodium acetate and 2-5 parts by weight of tri-ethanolamine and the balance to make parts by weight being water, said concentrate being diluted with water to give a total active material concentration in final dilution of in excess of about 5.4% by weight and said final aqueous composition being coated on said metal surface.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=19752053

Family Applications (1)

Country Status (5)

Cited By (2)

Citations (1)

Family Cites Families (1)

• 0
  • BE BE597460D patent/BE597460A/xx unknown
  • NL NL245796D patent/NL245796A/xx unknown
• 1960
  • 1960-09-19 US US56669A patent/US3050360A/en not_active Expired - Lifetime
  • 1960-11-24 DE DES71406A patent/DE1185450B/de active Pending
  • 1960-11-24 GB GB40424/60A patent/GB888682A/en not_active Expired

Patent Citations (1)

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