36. Why is it necessary to soak steel pipes in hot water for a period before acid washing in certain operations?

Prior to acid washing, steel pipes should be preheated in hot water (25-50℃) for 1-3 minutes before the process begins. This practice offers multiple benefits: (1) It removes iron filings, contaminants, and minor oil residues from unalkalized pipe blanks, while also enhancing neutralization efficiency for alkalized blanks; (2) Preheating accelerates acid washing; (3) It reduces direct heating of the acid solution, prolonging its dilution effect; (4) The solution remains cleaner, ensuring superior acid washing quality; (5) It saves approximately 2-3% of acid consumption.