Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
  • B08B9/02—Cleaning pipes or tubes or systems of pipes or tubes
  • B08B9/027—Cleaning the internal surfaces; Removal of blockages
  • B08B9/032—Cleaning the internal surfaces; Removal of blockages by the mechanical action of a moving fluid, e.g. by flushing
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/02—Inorganic compounds
  • C11D7/04—Water-soluble compounds
  • C11D7/08—Acids
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/26—Organic compounds containing oxygen
  • C11D7/265—Carboxylic acids or salts thereof
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D7/00—Compositions of detergents based essentially on non-surface-active compounds
  • C11D7/22—Organic compounds
  • C11D7/32—Organic compounds containing nitrogen
  • C11D7/3218—Alkanolamines or alkanolimines
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
• • E—FIXED CONSTRUCTIONS
  • E03—WATER SUPPLY; SEWERAGE
  • E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
  • E03B7/00—Water main or service pipe systems
  • E03B7/006—Arrangements or methods for cleaning or refurbishing water conduits
• • C—CHEMISTRY; METALLURGY
  • C11—ANIMAL OR VEGETABLE OILS, FATS, FATTY SUBSTANCES OR WAXES; FATTY ACIDS THEREFROM; DETERGENTS; CANDLES
  • C11D—DETERGENT COMPOSITIONS; USE OF SINGLE SUBSTANCES AS DETERGENTS; SOAP OR SOAP-MAKING; RESIN SOAPS; RECOVERY OF GLYCEROL
  • C11D2111/00—Cleaning compositions characterised by the objects to be cleaned; Cleaning compositions characterised by non-standard cleaning or washing processes
  • C11D2111/10—Objects to be cleaned
  • C11D2111/14—Hard surfaces
  • C11D2111/20—Industrial or commercial equipment, e.g. reactors, tubes or engines

Definitions

• scale and sedimentation will increase the possibility of corrosion in the water distribution pipe along with promoting the growth of organisms.
• the organisms also can be a health hazard, promoting corrosion and biomass which binds scale and sediment together and to the surfaces of the system. Corrosion will eventually lead to the leakage of the system and the necessity to replace the leaking section.
• a proper cleaning and maintenance program fo water distribution systems will prevent decreased wate flow capacity, corrosion and the necessity to replac the system or portions thereof.
• SUMMARY OF THE INVENTION This invention is directed to a method o cleaning and maintaining water distribution systems Water systems having interior scale and sedimen deposits are cleaned by introducing and circulating a effective amount of an aqueous treatment solution fo a sufficient period of time which results in th solution, loosening and suspension of the undesire scale and sediment. Thereafter, the spent treatin solution containing the dissolved or suspended scal and sediment is flushed from the water distributio system to provide a clean system with improved wate flow and operation. Additionally, further flushin with high pressure water will also remove additiona scale that had been loosened by the treating solution.
• the cleaning solution may be acidic, neutra or basic.
• mineral acids or organic acids in potable wate pipe systems, mineral acids or organic acids, an mixtures thereof, are employed as acidic treatmen solutions.
• the acidic treatment solution may contai further additives such as inhibitors, chelating agents, penetrating and/or dispersing agents to assist in the removal of scale and sediment and to minimize any adverse effects on the pipes, valves, or other system surfaces due to the acids employed.
• This invention provides a simple, low cost and effective method of removing water scale and sediment from water distribution systems in order to maintain proper water flow, operation and to prevent corrosion of the system which would require the high cost and inconvenience of replacement.
• acidic treatment solutions found to be useful in practicing the method of this invention are aqueous solutions of mineral acids such as hydrochloric, nitric, phosphoric, polyphosphoric, hydrofluoric, boric, sulfuric, sulfurous, and the like.
• Aqueous solutions of mono-, di- and polybasic organic acids have also been found to be useful and include formic, acetic, propionic, citric, glycolic, lactic, tartaric, polyacrylic, succinic, p-toluenesulfonic, and the like.
• the useful treatment solutions may also be aqueous mixtures of the above mineral and organic acids. Alkaline, acid, or neutral cleaning solutions may also be employed, as indicated above, dependin upon the type of scale that needs to be removed.
• Sequestering or chelating agents such as EDT (ethylenediamine tetraacetic acid) , NT (nitrilotriacetic acid), and derivatives, i.e., basic alkali salts, and the like have also been found to be useful in the treatment solution in certain cases.
• EDT ethylenediamine tetraacetic acid
• NT nitrilotriacetic acid
• derivatives i.e., basic alkali salts, and the like have also been found to be useful in the treatment solution in certain cases.
• the acidic treatment solution may also contain acid inhibitors which substantially reduce the acidic action on metal surfaces of the water distribution system, particularly valves, fire hydrants, etc. , and these various inhibitors for acids have been well documented in the patent art. Typical, but not necessarily all inclusive, examples of acid inhibitors are disclosed in the following U.S. Patents:
• the treatment solution may also contain dispersing, penetrating or emulsifying agents to assist in the removal of the scale and sediment.
• These surface active agents may be anionic, cationic, nonionic or amphoteric as defined in the art.
• Compounds such as alkyl ether sulfates, alkyl or aryl sulfates, alkanolamines, ethoxylated alkanolamides, a ine oxides, ammonium and alkali soaps, betaines, hydrotropes such as sodium aryl sulfonates; ethoxylated and propoxylated fatty alcohols and sugars, ethoxylated and propoxylated alkylphenols, sulfonates, phosphate esters, quarternaries, sulfosuccinates, and mixtures thereof, have been found to be useful in admixture with the acid treating solution.
• Fig. 1 is a schematic of a laboratory test system illustrating the method of this invention.
• Fig. 2 is a diagram of a field system for cleaning a potable water distribution system.
• a laboratory test system is shown to evaluate the removal of scale and sediment by acidic treating solutions from a test pipe sample taken from a water distribution system.
• This system includes a 15 gallon acidic treating solution reservoir 5, submersible acidic treating solution circulation pump 6 rated at 1200 gallons per hour, 1" inlet transfer line 7, drain valve 8, heavy rubber diaphragm seals 9 for the ends of the test pipe specimen 10, 1" outlet transfer line 11 and the treating solution 12.
• the test pipe specimen 10 is mounted at about a 30 degree angle so that the test solution will contact essentially the entire inner pipe surface to be treated.
• the scale on th inside of the pipe consisted of nodules of up to 1 t 1% inches in height covering 100% of the inside pip surface which had substantially reduced the openin inside the pipe for water to flow.
• Analysis of th scale indicated it consisted of primarily iron wit some calcium, magnesium and manganese in the for oxides, hydroxides and carbonates along with fin mineral acid insoluble solids and some "biomass". This is typical scale associated with sulfate-reducing an iron bacteria along with the associated corrosion.
• a field equipment and system diagram is shown which may be employed i the cleaning of a potable water pipe distributio system.
• Two 500 gallon treating solution reservoir tanks 20 and 21 along with a 100 gallon per minut circulation pump 22 and sight glass 23 are mounted o a flat bed truck (not shown) .
• a 2% inlet pipe 24 is secured to a 650 foot section of 6" water distribution pipe 25 after the main shut off valve 26.
• the fire hydrant 27 and fire hose 28 were employed for the acidic treating solution return to tanks 20 and 21.
• the section of pipe 25 to be treated was isolated by closing off the two water main shut-off valves 26 and 29 along with all service line valves, typically 30 and 31. With valves 32 and 33 closed, 1000 gallons of acidic treating solution was prepared in tanks 20 and 21. With the coupling 34 open, th treating solution was allowed to enter the system b opening valves 33 and 35 and turning on the circulatio pump 22. The pH of the water coming from the ope coupling was then monitored until a decrease was note which indicated the acid treating solution ha displaced the water in the section to be treated. Th circulation pump 22 was turned off and the coupling 34 connected. Valves 36 and 37 were then closed and valv 32 opened for circulation. The circulation pump 22 was then started again for the treatment period. Valve 37 was closed to allow for scale solids to accumulate i tank 20 while the treating solution could overflow a 38 to tank 21 which reduces the chances of pluggin during treatment.
• the treating solution was then circulated i the system of Fig. 2 for a period of 5 hours. Observation of the treating solution through the sigh glass 23 showed an increasingly darker discoloratio with time.
• th circulation pump 22 was turned off, and valves 33 an 35 were closed.
• the main shut-off valve 26 was slowl opened and fresh water allowed to enter the syste until the treating solution was displaced as noted whe the tanks 20 and 21 were full. Valve 32 was the closed.
• the fire hose 28 was then disconnected fro the fire hydrant 27 and the main shut-off valve 2 opened full to allow high pressure flushing of th treated water main 25. As the flush water emerged fr the fire hydrant 27 it was dark in color wi considerable scale and sediment solids. Flushi continued until the flush water was clean of solids f 5 a period of time prior to putting the treated secti of the water distribution system back into service.
• preblended cleaning solution is used in an amoun of about 12.5% by weight with water in the field fo cleaning an underground potable water distribution pip system.
• the solution may b employed in amounts of from about 5 to about 50% b weight with water in the field, depending upon suc variables as the amount of scale, pipe volume to b cleaned, circulation time and other factors.
• Th amounts of anhydrous chemicals in a broader range o ingredients are about 1% to 27% HC1, 0.1% to 4 glycolic acid, 0.04% to 1% sodium xylene sulfonate an a b o u t 0 . 1 % t o 2 . 5 % o f t h triethanolamine/diethanolomine mixture (hereinafte referred to as "TEA”) .
• TAA triethanolamine/diethanolomine mixture
• the abov chemical ingredients may be blended in the field fo cleaning the underground potable pipes, for example, hydrochloric acid may be added to a concentrate of th glycolic acid, sodium xylene sulfonate and TEA.
• hydrochloric acid may be added to a concentrate of th glycolic acid, sodium xylene sulfonate and TEA.
• th potable water distribution systems an undergroun section of the pipe to be cleaned is sealed off fro the rest of the system.
• the cleaning solution is then introduced from a tan into the pipe section and, if water is in that sectio of pipe, it is removed upon the introduction of th cleaning solution.
• circulation o the cleaning solution through the underground pipe i initiated for a sufficient period of time fo solubilization, loosening and/or suspension of th scale and sediments.
• a soap having a 1:1 stoichiometric equivalent of the acid (HC1 and glycolic acid) and TEA base is formed with an excess of the acid.
• This composition has been found to work effectively in the field for the removal of scale associated with sulfate-reducing and iron bacteria consisting primarily of iron oxide, biomass and sediment.
• These 1:1 soaps have also been described in the above referred to co-pending Application Serial No. 07/700,780, filed May 16, 1991, now U.S. Patent No. and the disclosure thereof is incorporated herein in its entirety by reference.
• These soaps may be more generally categorized as soaps of mineral and/or organic acids and a base such as an amine and ammonia.
• soaps include 1:1 soaps of TEA and glycolic acid (also known as hydroxyacetic acid) ; TEA and acetic acid; TEA and citric acid; TEA and benzoic acid; hydrochloric acid and ammonia; sulfuric acid and ammonia; nitric acid and ammonia; TEA and hydrochloric acid; TEA and sulfuric acid; TEA and nitric acid; ammonia and glycolic acid; ammonia and benzoic acid; and ammonia and p- toluenesulfonic acid. Accordingly, it will be understood that other cleaning solutions of the acidic type employing 1:1 soaps may be employed to effectively solubilize, loosen and/or suspend the scale and sediment from the potable pipe in accordance with th principles of this invention.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Wood Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Mechanical Engineering (AREA)
• Emergency Medicine (AREA)
• Inorganic Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Hydrology & Water Resources (AREA)
• Public Health (AREA)
• Water Supply & Treatment (AREA)
• Cleaning In General (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Detergent Compositions (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Processing Of Solid Wastes (AREA)

Applications Claiming Priority (5)

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• 1994
  • 1994-03-22 WO PCT/US1994/003065 patent/WO1994021865A1/en active IP Right Grant
  • 1994-03-22 CA CA002157916A patent/CA2157916C/en not_active Expired - Fee Related
  • 1994-03-22 BR BR9406139A patent/BR9406139A/pt not_active IP Right Cessation
  • 1994-03-22 AT AT94912283T patent/ATE170583T1/de active
  • 1994-03-22 JP JP52131394A patent/JP3597193B2/ja not_active Expired - Fee Related
  • 1994-03-22 EP EP94912283A patent/EP0690944B1/de not_active Expired - Lifetime
  • 1994-03-22 DE DE69413017T patent/DE69413017T2/de not_active Expired - Fee Related
  • 1994-03-22 AU AU64903/94A patent/AU673426B2/en not_active Ceased

Non-Patent Citations (1)

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