What types of water soluble acids are included in petroleum products?

What types of water soluble acids are included in petroleum products?‌

Water-soluble acids in petroleum products‌ primarily fall into the following two categories, along with their detection significance and typical representatives:

‌1. Inorganic Acids‌

‌Sulfuric acid (H₂SO₄)‌: Highly corrosive, prone to causing rust in metal equipment, often found in low-quality oils or as refining process residues.

‌Hydrochloric acid (HCl)‌: Volatile, typically introduced during processing via chloride ion contamination.

‌2. Organic Acids‌

‌Low-molecular-weight organic acids‌ (e.g., formic acid, acetic acid):

Formic acid (HCOOH): Strongly corrosive, may accelerate oil oxidation.

Acetic acid (CH₃COOH): Commonly produced from the degradation of oxygen-containing additives.

‌Petroleum sulfonic acids (RSO₃H)‌:

Acidic precursors to sodium petroleum sulfonate (RSO₃Na), used as rust inhibitors but can corrode aluminum if overused.

‌Naphthenic acids (CnH₂n-1COOH)‌:

Naturally present in crude oil; high-carbon esters can serve as lubricants, but acidic components require control.

‌Detection Significance & Standards‌

‌Hazards‌: Water-soluble acids corrode metals (especially copper and iron) and promote oil oxidation and gum formation.

‌Testing Methods‌:

‌GB/T 259-88‌: Measured using methyl orange/phenolphthalein indicators or pH meters.

‌ASTM D664‌: Potentiometric titration for total acid number determination.

‌Typical Applications‌

‌Electrical equipment oils‌ (e.g., transformer oils): Strict control of water-soluble acids is critical.

‌Engine lubricants‌: Acidic substances must be avoided to prevent bearing corrosion.

SH259B automatic water-soluble acid tester is designed and produced in accordance with GB/T7598-2008 "running transformer oil turbine oil water-soluble acid determination method (colorimetric method)" and GB/T 259 "petroleum products water-soluble acid and alkali determination method", specially used for transformer oil, turbine oil, oil resistance and other petroleum products water-soluble acid (pH) determination.