The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 07, 1976
Filed:
Aug. 28, 1975
Halliburton Company, Duncan, OK (US);
Abstract
Iron containing scale is removed from a metallic substrate by contacting the scale with a composition which is an aqueous solution consisting essentially of at least 0.5 weight percent of a polyphosphonic acid, or an alkali metal or amine salt of such acid, with the acid being selected from the group of acids having the formulae: ##STR1## where R.sub.1 is selected from the class consisting of C.sub.1 -C.sub.12 alkyl groups, and the group ##STR2## and ##STR3## where R.sub.2 is selected from the class consisting of --H, --PO.sub.3 H.sub.2, C.sub.1 -C.sub.12 alkyl groups, and the group ##STR4## The scale is removed from the metallic substrate by contacting THE DESCRIBED SCALE-BEARING SUBSTRATE WITH THE DESCRIBED COMPOSITION AT SELECTED TEMPERATURE AND PH conditions, and over a controlled time period and iron concentration in the composition so that the formation of an undesirable polymeric precipitate in the cleaning solution is avoided. Formation of the precipitate is also avoided by adding ammonium bifluoride to the composition.