| abstract |
Acid-soluble and/or hydrolyzable obstructions are removed from conduits by contacting such obstructions with a composition containing urea and sulfuric acid in which the urea/sulfuric acid molar ratio is less than 2. The urea/sulfuric acid compositions may optionally contain other components such as surfactants and/or non-aqueous polar solvents which accentuate the activity of the compositions toward hydrophobic materials. Urea-sulfuric acid compositions which contain water and which have H 2 O/(urea+H 2 SO 4 ) molar ratios below about 2.5 are particularly useful for removing obstructions by partial or complete hydrolysis. |