Anti-corrosion of crude oil tanks

Crude oil tank 1 – Corrosion prevention measures for the interior of the crude oil tank: (1) The areas that require corrosion protection inside the tank include the bottom plate, the inner walls of the tank (2 meters above and below the ring plates), and the floating roof. (II) Design principles for corrosion prevention in crude oil tanks: 1. The bottom plate inside the tank shall be protected using a combination of coating and sacrificial anodes; the coating must not conduct static electricity, and its thickness shall be no less than 120 um. 2The remaining parts are protected with an antistatic coating, with a total coating thickness of not less than 180um. For new tanks, it is recommended to use metal thermal spraying combined with an antistatic coating as a sealing measure. (III) Requirements for the selection of anti-corrosion coatings in crude oil tanks: 1. For the tank bottom, epoxy resin-based coatings, polyurethane-based coatings, an inorganic zinc silicate primer combined with a modified epoxy topcoat (recommended for new tanks), or other types of non-metallic coatings can be used ； 2. In principle, the inner walls should be coated with epoxy antistatic coatings, epoxy chlorosulfonated polyethylene antistatic coatings, polyurethane antistatic coatings, phenol-modified antistatic coatings, etc ； 3. For the floating roof and the 2-meter-high ring plate on the upper part of the tank wall, it is recommended to use an acrylic polyurethane antistatic coating as the topcoat. 4. For the sealing coating, an acrylic polyurethane antistatic sealing coating is recommended ； 5 For antistatic coatings, it is recommended to use those that contain metal powder as a conductive agent. (IV) Methods and standards for surface pre-treatment to prevent corrosion in crude oil tanks: After surface cleaning, sandblasting should be carried out to remove rust. The coating application is required to meet the Sa2.5 grade specified in GB 8923—88 \"Corrosion grades and rust removal grades of steel surfaces prior to painting\", while metal thermal spraying is required to meet the Sa3 grade specified in the same standard. II. External anti-corrosion scheme for crude oil tanks (1) The scope of external anti-corrosion for crude oil tanks includes: the outer wall, the outer roof, and the outer bottom of the tank. (II) Design principles for the external anti-corrosion measures of crude oil tanks 1. For the anti-corrosion protection of the outer bottom of crude oil tanks, any one of the following three methods can be chosen: 1) Epoxy-bitumen anti-corrosion coating + cathodic protection; 2) Inorganic zinc-rich paint + basic impermeabilization treatment; 3) Epoxy-coal tar paint + basic impermeabilization treatment. For newly built crude oil tanks, it is recommended to use epoxy-coal tar anti-corrosion coating combined with cathodic protection for the outer bottom. 2. The outer walls of crude oil tanks equipped with insulation should have an anti-rust paint primer followed by insulation layers. 3. Outer walls without insulation should be covered with external anti-corrosion coatings, with a thickness of not less than 80 um. 4 The outer wall of the tank roof should be coated with a topcoat with excellent weather resistance. (III) Requirements for the selection of anti-corrosion coatings for crude oil tanks: 1. For ordinary atmospheric corrosion environments, conventional blended paints can be used ； In environments with harsh chemical atmospheres or severe corrosion in coastal areas, resorcinol resin paints, epoxy coal tar pitch paints, vinyl chloride coatings, chlorosulfonated polyethylene coatings, polyurethane coatings, acrylic polyurethane coatings, or organic and inorganic zinc-rich paints should be used. It is also necessary to have a proper combination of primer and topcoat. For the outer walls of tank tops, topcoat materials with excellent weather resistance such as acrylic polyurethane should be employed. (IV) Methods and requirements for anti-corrosion surface treatment of crude oil tanks: Rust removal for coating application can be carried out manually or with mechanical tools, and the required standard is St2–5t3 as specified in GB 8923—88.

This post was last edited by “Handsome Pig” on July 18, 2011, at 08:20. Thanks for your reply, brother, but none of the answers addressed what I asked about :L Also, it seems that the coating thickness you mentioned doesn’t comply with GB50393-2008

The reason for using two different types of anti-corrosion coatings in crude oil tanks is that the composition of crude oil is quite complex, containing sulfur, hydrogen sulfide, various salts, water, and other impurities, which cause severe corrosion at the bottom of the tank. Therefore, an antistatic coating is used on the upper part, while an insulating anti-corrosion coating is used on the lower part. There are many types of antistatic coatings available in China, and any certified, legitimate product can be used. For the lower part, a chemical-resistant epoxy anti-corrosion coating should be used; phenolic-epoxy anti-corrosion coatings are the best choice as they provide better protection.

Last time, I encountered one that required a 3PE anti-corrosion grade

This post was last edited by lbf-ecommerce-z on 2015-11-13 at 13:29. An insulating anti-corrosion coating is used below the bottom plate of the crude oil tank and the oil-water interface, as this area requires cathodic protection. Insulating coatings can only be used together with cathodic protection coatings. Shuangshi Coatings – specialized in tank anti-corrosion. Original text of the standard: ———————————————————— The outer bottom plate of steel oil storage tanks with a capacity of over 1000 m3 shall be subjected to cathodic protection, and the design life of this cathodic protection system shall be no less than 20 years ； The outer bottom plates of newly constructed oil storage tanks with a capacity of 100,000 m3 or more shall be protected by forced current cathodic protection, and the designed service life of this cathodic protection system shall be no less than 40 years.

It’s definitely not due to the price; it’s because the underlying medium contains water, which requires not only insulating coatings but also an anti-corrosion process using sacrificial anodes.