NZ622478B2 - Weld cleaning fluid - Google Patents
Weld cleaning fluid Download PDFInfo
- Publication number
- NZ622478B2 NZ622478B2 NZ622478A NZ62247812A NZ622478B2 NZ 622478 B2 NZ622478 B2 NZ 622478B2 NZ 622478 A NZ622478 A NZ 622478A NZ 62247812 A NZ62247812 A NZ 62247812A NZ 622478 B2 NZ622478 B2 NZ 622478B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- acid
- salt
- composition
- edta
- cleaning
- Prior art date
Links
- 238000004140 cleaning Methods 0.000 title claims abstract description 83
- 239000012530 fluid Substances 0.000 title claims abstract description 38
- 239000002253 acid Substances 0.000 claims abstract description 63
- 239000000203 mixture Substances 0.000 claims abstract description 62
- 150000003839 salts Chemical class 0.000 claims abstract description 47
- 239000011780 sodium chloride Substances 0.000 claims abstract description 47
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 40
- KCXVZYZYPLLWCC-UHFFFAOYSA-N edta Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims abstract description 34
- 229910052751 metal Inorganic materials 0.000 claims abstract description 27
- 239000002184 metal Substances 0.000 claims abstract description 27
- 239000003352 sequestering agent Substances 0.000 claims abstract description 22
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims abstract description 21
- LWIHDJKSTIGBAC-UHFFFAOYSA-K Tripotassium phosphate Chemical compound [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 claims abstract description 20
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 14
- 239000007864 aqueous solution Substances 0.000 claims abstract description 14
- VEXZGXHMUGYJMC-UHFFFAOYSA-N HCl Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000002738 chelating agent Substances 0.000 claims abstract description 11
- 230000001264 neutralization Effects 0.000 claims abstract description 10
- GRYLNZFGIOXLOG-UHFFFAOYSA-N nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 9
- 159000000001 potassium salts Chemical class 0.000 claims abstract description 8
- 159000000000 sodium salts Chemical group 0.000 claims abstract description 7
- 229910001220 stainless steel Inorganic materials 0.000 claims description 29
- 239000010935 stainless steel Substances 0.000 claims description 28
- 235000011007 phosphoric acid Nutrition 0.000 claims description 20
- 239000011734 sodium Substances 0.000 claims description 15
- 239000003205 fragrance Substances 0.000 claims description 14
- 238000004040 coloring Methods 0.000 claims description 12
- 235000019798 tripotassium phosphate Nutrition 0.000 claims description 9
- KEAYESYHFKHZAL-UHFFFAOYSA-N sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 claims description 7
- 229910052708 sodium Inorganic materials 0.000 claims description 7
- BZKBCQXYZZXSCO-UHFFFAOYSA-N sodium hydride Inorganic materials [H-].[Na+] BZKBCQXYZZXSCO-UHFFFAOYSA-N 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 6
- 229910000404 tripotassium phosphate Inorganic materials 0.000 claims description 6
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 claims description 5
- 229910052700 potassium Inorganic materials 0.000 claims description 5
- 239000011591 potassium Substances 0.000 claims description 5
- FTEDXVNDVHYDQW-UHFFFAOYSA-N Ca(II)-BAPTA Chemical compound OC(=O)CN(CC(O)=O)C1=CC=CC=C1OCCOC1=CC=CC=C1N(CC(O)=O)CC(O)=O FTEDXVNDVHYDQW-UHFFFAOYSA-N 0.000 claims description 4
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 claims description 4
- DEFVIWRASFVYLL-UHFFFAOYSA-N ethylene glycol bis(2-aminoethyl)tetraacetic acid Chemical compound OC(=O)CN(CC(O)=O)CCOCCOCCN(CC(O)=O)CC(O)=O DEFVIWRASFVYLL-UHFFFAOYSA-N 0.000 claims description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 3
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 239000011572 manganese Substances 0.000 claims description 3
- 159000000003 magnesium salts Chemical class 0.000 claims description 2
- 229940022766 EGTA Drugs 0.000 claims 2
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 abstract description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 72
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 27
- 239000000243 solution Substances 0.000 description 26
- 239000007788 liquid Substances 0.000 description 21
- 238000002161 passivation Methods 0.000 description 15
- 239000000975 dye Substances 0.000 description 14
- 239000002304 perfume Substances 0.000 description 11
- 238000003466 welding Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 230000002378 acidificating Effects 0.000 description 7
- 230000005591 charge neutralization Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 238000006386 neutralization reaction Methods 0.000 description 7
- 229910000831 Steel Inorganic materials 0.000 description 6
- 150000007513 acids Chemical class 0.000 description 6
- 238000009472 formulation Methods 0.000 description 6
- 239000003517 fume Substances 0.000 description 6
- 239000010959 steel Substances 0.000 description 6
- 239000002585 base Substances 0.000 description 5
- -1 oxo anions Chemical class 0.000 description 5
- 238000005498 polishing Methods 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 150000001450 anions Chemical class 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 229910000460 iron oxide Inorganic materials 0.000 description 4
- 235000013980 iron oxide Nutrition 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- 239000008399 tap water Substances 0.000 description 4
- 235000020679 tap water Nutrition 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-N HF Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 3
- 210000003491 Skin Anatomy 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 239000012467 final product Substances 0.000 description 3
- 235000013305 food Nutrition 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- VBMVTYDPPZVILR-UHFFFAOYSA-N iron(2+);oxygen(2-) Chemical class [O-2].[Fe+2] VBMVTYDPPZVILR-UHFFFAOYSA-N 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 229910000160 potassium phosphate Inorganic materials 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000002344 surface layer Substances 0.000 description 3
- UEUXEKPTXMALOB-UHFFFAOYSA-J tetrasodium;2-[2-[bis(carboxylatomethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical compound [Na+].[Na+].[Na+].[Na+].[O-]C(=O)CN(CC([O-])=O)CCN(CC([O-])=O)CC([O-])=O UEUXEKPTXMALOB-UHFFFAOYSA-J 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- GNSKLFRGEWLPPA-UHFFFAOYSA-M Monopotassium phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- 229960003330 Pentetic Acid Drugs 0.000 description 2
- DWHVYWQQVLHNFI-UHFFFAOYSA-N [N+](=O)(O)[O-].[Fe-3](C#N)(C#N)(C#N)(C#N)(C#N)C#N.[K+].[K+].[K+] Chemical compound [N+](=O)(O)[O-].[Fe-3](C#N)(C#N)(C#N)(C#N)(C#N)C#N.[K+].[K+].[K+] DWHVYWQQVLHNFI-UHFFFAOYSA-N 0.000 description 2
- 239000004480 active ingredient Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910000423 chromium oxide Inorganic materials 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 229910000365 copper sulfate Inorganic materials 0.000 description 2
- 229940058180 edetate dipotassium anhydrous Drugs 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- OKKJLVBELUTLKV-UHFFFAOYSA-N methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001681 protective Effects 0.000 description 2
- 239000001044 red dye Substances 0.000 description 2
- WGLPBDUCMAPZCE-UHFFFAOYSA-N trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- FBOUIAKEJMZPQG-AWNIVKPZSA-N (1E)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pent-1-en-3-ol Chemical compound C1=NC=NN1/C(C(O)C(C)(C)C)=C/C1=CC=C(Cl)C=C1Cl FBOUIAKEJMZPQG-AWNIVKPZSA-N 0.000 description 1
- PIICEJLVQHRZGT-UHFFFAOYSA-N 1,2-ethanediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 1
- 229910000619 316 stainless steel Inorganic materials 0.000 description 1
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- 229910000906 Bronze Inorganic materials 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L Copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 239000004150 EU approved colour Substances 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L Iron(II) sulfate Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- 239000007836 KH2PO4 Substances 0.000 description 1
- AJDUTMFFZHIJEM-UHFFFAOYSA-N N-(9,10-dioxoanthracen-1-yl)-4-[4-[[4-[4-[(9,10-dioxoanthracen-1-yl)carbamoyl]phenyl]phenyl]diazenyl]phenyl]benzamide Chemical compound O=C1C2=CC=CC=C2C(=O)C2=C1C=CC=C2NC(=O)C(C=C1)=CC=C1C(C=C1)=CC=C1N=NC(C=C1)=CC=C1C(C=C1)=CC=C1C(=O)NC1=CC=CC2=C1C(=O)C1=CC=CC=C1C2=O AJDUTMFFZHIJEM-UHFFFAOYSA-N 0.000 description 1
- 240000002799 Prunus avium Species 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 125000004429 atoms Chemical group 0.000 description 1
- 235000013361 beverage Nutrition 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010974 bronze Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000006388 chemical passivation reaction Methods 0.000 description 1
- 235000019693 cherries Nutrition 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 150000004683 dihydrates Chemical class 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- QLBHNVFOQLIYTH-UHFFFAOYSA-L dipotassium;2-[2-[bis(carboxymethyl)amino]ethyl-(carboxylatomethyl)amino]acetate Chemical compound [K+].[K+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O QLBHNVFOQLIYTH-UHFFFAOYSA-L 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- VTLYFUHAOXGGBS-UHFFFAOYSA-N fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 229910001447 ferric ion Inorganic materials 0.000 description 1
- 229910001448 ferrous ion Inorganic materials 0.000 description 1
- 239000011790 ferrous sulphate Substances 0.000 description 1
- 235000003891 ferrous sulphate Nutrition 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000003349 gelling agent Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxyl anion Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000002462 imidazolines Chemical class 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 150000002506 iron compounds Chemical class 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 1
- 150000004715 keto acids Chemical class 0.000 description 1
- 239000012263 liquid product Substances 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910000402 monopotassium phosphate Inorganic materials 0.000 description 1
- 235000019796 monopotassium phosphate Nutrition 0.000 description 1
- 229940006093 opthalmologic coloring agents Diagnostic Drugs 0.000 description 1
- 230000001590 oxidative Effects 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229940083254 peripheral vasodilators Imidazoline derivatives Drugs 0.000 description 1
- 150000003016 phosphoric acids Chemical class 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N phosphorous acid Chemical compound OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- 229920000137 polyphosphoric acid Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propanol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 1
- 230000002269 spontaneous Effects 0.000 description 1
- 238000010186 staining Methods 0.000 description 1
- 229910001256 stainless steel alloy Inorganic materials 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000001043 yellow dye Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F1/00—Electrolytic cleaning, degreasing, pickling or descaling
- C25F1/02—Pickling; Descaling
- C25F1/04—Pickling; Descaling in solution
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F7/00—Constructional parts, or assemblies thereof, of cells for electrolytic removal of material from objects; Servicing or operating
Abstract
Disclosed is a weld cleaning fluid composition comprising an aqueous solution having a pH that is approximately neutral, said aqueous solution having from 10% to 60% by weight of a salt of an acid selected from one or more of a phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, or citric acid, and having up to 20% by weight of a salt of a polyaminocarboxylic acid as a sequestering or chelating agent. In a preferred embodiment, the salt of an acid is a potassium or sodium orthophosphate salt and the sequestering or chelating agent is a sodium and/or potassium salt of EDTA. Also disclosed is a method of cleaning or passivating a metal surface using the weld cleaning fluid composition and an electro-cleaning apparatus. c acid, and having up to 20% by weight of a salt of a polyaminocarboxylic acid as a sequestering or chelating agent. In a preferred embodiment, the salt of an acid is a potassium or sodium orthophosphate salt and the sequestering or chelating agent is a sodium and/or potassium salt of EDTA. Also disclosed is a method of cleaning or passivating a metal surface using the weld cleaning fluid composition and an electro-cleaning apparatus.
Description
Weld Cleaning Fluid
TECHNICAL FIELD
The present invention relates to a weld cleaning fluid. Stainless steel welds,
such as those done by TIG welding, require cleaning to remove the resulting
surface discolouration and also to passivate the steel. This is commonly
carried out using an electro-cleaning apparatus with the assistance of
electrolyte cleaning fluids. Typically, these cleaning fluids contain
phosphoric acid as their primary active ingredient, and as a consequence
have a low (acidic) pH. After use, these fluids pose a problem of disposal in
an environmentally acceptable way, and being acidic require greater care in
order to be used safely. A new cleaning fluid has been developed that has a
generally neutral pH, avoiding these environmental and safety issues. This
fluid has also been found to give an improved result over existing cleaning
fluids. The cleaning fluid composition of the present invention preferably has
sodium and/or potassium orthophosphate as the main active ingredient, or
similar such salts, and has a pH of around 7.
BACKGROUND ART
When stainless steel is welded, the resulting join and its surrounding area
are often discoloured and this area (if untreated) then becomes susceptible
to corrosion. This weld burn that appears, after welding with a TIG (ie,
“Tungsten Inert Gas” arc welding) welder for instance, therefore normally
has to be cleaned, and this is often carried out using an electro-chemical
cleaning system in recent times. That cleaning system involves using an
electro-cleaning unit that applies a low voltage, high current, flow in a
circuit with the metal connected as the anode. A tool, providing the
cathode, is rubbed over the heat tinted sections of the weld and its
surrounding metal, with the aid of an electrolytic weld cleaning fluid, to
complete the circuit. The tool heats and passivates the metal surface, and
removes the unwanted discolouration. The passivation treatment restores
its natural protection against corrosion to the stainless steel.
In addition, when there is a need to provide a bright mirror finish to the
stainless steel, which is particularly important when the steel article is used
in the food industry, or when a decorative appearance is needed, for
example, then a similar system for electro-polishing is also utilised using
the same type of electrolytic polishing fluid.
Traditionally in the past, weld discolouration was removed using a pickling
paste that usually consisted of a composition of nitric acid and hydrofluoric
acid. This paste was manually wiped on to the stains on the welds and the
surrounding area, left in place until the stain had been removed, and then
washed off. These acids are dangerous and difficult to apply and remove.
The waste and fumes that result have to be handled carefully, being
dangerous to breathe in or have skin contact with, and the waste liquid
generated is environmentally hazardous to dispose of.
More recently, electro-chemical cleaning or polishing has been utilised to
achieve this same purpose, and this has been found to often give a better
result. Electro-chemical cleaning (or “electro-cleaning”) also produces a
better finish to the metal, since pickling will roughen the surface while
electro-cleaning smooths it.
Electro-cleaning (or polishing) basically involves using an electrical power
source that is connected in a circuit to the steel surface which becomes the
anode, and with an electrically conductive “wand” tool comprising the
cathode. The wand can be in the form of a copper electrode, surrounded by
a nylon sponge or felt pad which is soaked with an electrolyte solution. Until
the current invention, this electrolyte solution was normally an aqueous
solution of phosphoric acid (ie, orthophosphoric acid H PO ). This wand is
used to rub and corrode away the top surface layers removing the
discolouration and iron oxide surface imperfections left from the welding. A
worker holds the wand by an insulated handle and presses it over the tinted
area until the normal stainless steel sheen is returned and the
discolouration removed.
More recently, the applicants for the present invention (Ensitech), have
developed an improved electro-cleaning system that utilises a conductive
carbon bristled brush (the “TIG Brush™”) that is used in place of the felt or
nylon pad type of wand. There is a power source that produces a low
voltage, high current, output that is used to remove the discolouration from
stainless steel TIG welds when the electrical current is flowing in the circuit.
The brush is dipped in the electrolytic cleaning solution and then the tips of
the conductive bristles are dragged across the tinted surface area. The
bristles allow the brush to penetrate into constricted areas, and any crevices
or pits in the metal, giving an excellent result. The electrical current passing
via the brush is thought to create a high temperature area on the surface of
the steel that hastens the deoxidising action of the cleaning fluid. The iron
oxides on the surface are dissolved to release free ferric and ferrous ions
and oxygen gas.
In addition, the welds in the stainless steel and the surrounding area then
require passivation to restore its resistance to corrosion. Stainless steel is
an alloy of iron that contains a significant amount (more than 10% and
commonly 13% to 27%) of chromium. The “stainless” quality of this steel is
caused by a thin durable film of chromium oxide that forms on its surface,
which will be naturally formed by the oxidation of the stainless steel alloy
with air or water. Welding disrupts this protective coating, and the iron
oxides that instead form on the surface cause the unwanted heat tint
staining, as well as allowing corrosion and pitting to occur subsequently.
Passivation restores the protective chromium oxide surface layer by
stripping away any iron oxides on the surface and simultaneously oxidising
the chromium atoms present to form the new surface layer.
Passivation generally is the process of removing the unwanted iron particles
on the surface and oxidising the chromium atoms that replace them, using
an oxidising agent like an acid, or by contact with air or water. The
Standard “ASTM A380”, defines passivation to be "the removal of
exogenous iron or iron compounds from the surface of stainless steel by
means of a chemical dissolution, most typically by a treatment with an acid
solution that will remove the surface contamination, but will not significantly
affect the stainless steel itself." It also describes passivation as "the
chemical treatment of stainless steel with a mild oxidant, such as a nitric
acid solution, for the purpose of enhancing the spontaneous formation of
the protective passive film."
For a long time, pickling and passivation of stainless steel involved using
acids, especially nitric acid, or a mixture or nitric and hydrofluoric acids, or
citric acid for stainless steel to be used in the food industry. More recently
with both types of the electro-cleaning units mentioned above, an
electrolytic and oxidising cleaning fluid has been used that consists of a
solution of phosphoric acid in water, together with a small quantity of
fragrance and colouring. This solution is acidic, with a low pH of
approximately pH 1 to 3. Probably because of the historic use of acids, and
their effectiveness with pickling and passivation, welding cleaning solutions
have all been acidic in nature.
Some passivation and cleaning procedures used in the past have also used
strongly basic or alkaline solutions with a high pH, for example using
aqueous solutions of sodium hydroxide, often in sequence with the acid
treatments.
These acidic (or basic) welding fluids create environmental problems with
their disposal after use, and have to be used with great care by the workers
carrying out the cleaning process to avoid splashing the fluid on to skin or
into eyes.
It has now been found that using a weld cleaning fluid that has a close to
neutral pH of around 7, can avoid at least some of the problems arising
from the acidic or alkaline fluids used in the past. Surprisingly, it has been
found that neutral pH weld cleaning and passivation fluids can give superior
results over the low (or high) pH fluids. Additionally the cleaning and
passivating treatment can proceed more quickly than with the prior known
fluids, giving an economic benefit as well as exposing workers to less of the
fumes that are given off during the cleaning process.
DISCLOSURE OF THE INVENTION
According to a first aspect of the invention there is provided a metal
cleaning composition comprising an aqueous solution having a pH that is
approximately neutral. Preferably, the metal cleaning composition is
adapted to clean the weld tint from stainless steel. The solution contains a
salt of an acid selected from any one or more of a phosphoric acid, nitric
acid, sulfuric acid, hydrochloric acid or citric acid, and most preferably the
acid is orthophosphoric acid, and a salt of a polyaminocarboxylic acid as a
sequestering or chelating agent. It is preferred that the salt of the acid is
selected from any one or more of potassium, sodium, ammonium,
manganese or magnesium salts, and most preferably the salt is potassium
and/or sodium. The salt of the acid may be one or more of the oxo anions
of potassium phosphate, selected from K PO , K HPO , and KH PO , and is
3 4 2 4 2 4
most preferably mostly tripotassium phosphate (K PO ). Sodium salt may
be used in place of some or all of the potassium salt.
When present, the K3PO4 (and its sodium and oxo anion equivalents, for
example) may be present in an amount of from 10% to 50% by weight, and
most preferably they may be present in an amount of about 35% by weight.
It is preferred that the sequestering or chelating agent is tetrasodium EDTA
(Na EDTA), or dipotassium EDTA dihydrate (K H EDTA). Another preferred
4 2 2
feature is that the composition may include at least one fragrance and/or
colouring agent.
Another aspect of the invention is a method of cleaning or passivating a
metal surface comprising the steps of: applying a low voltage high ampage
electrical current to the metal being the anode, and wiping the surface with
a conductive wand or brush being the cathode, forming an electrical circuit,
whereby an electrolytic fluid is applied to the surface in contact with the
wand or brush; characterised in that the electrolytic fluid comprising an
aqueous solution with a pH that is approximately neutral, comprising a
solution of a salt of an acid selected from any one or more of a phosphoric
acid, nitric acid, sulfuric acid, hydrochloric acid or citric acid, and a salt of a
polyaminocarboxylic acid as a sequestering or chelating agent. It is
preferred that the metal surface is cleaned to remove weld tint from
stainless steel.
Ideally, the electrolytic fluid may comprise a major part of the salt of the
acid comprising one or more of the oxo anions of potassium phosphate,
selected from K PO , K HPO , and KH PO . More preferably, the electrolytic
3 4 2 4 2 4
fluid may comprise a major part of an aqueous solution of tripotassium
phosphate (K PO ) and its sodium and oxo anion equivalents. The salt of
the polyaminocarboxylic acid is preferably tetrasodium EDTA or dipotassium
EDTA dihydrate. The electrolytic fluid may contain at least one colouring
agent and/or a fragrance.
In this specification, reference is made to cleaning and polishing
discolouration arising from the welding of stainless steel. This is a preferred
use for the present invention. However, the invention can also be utilised in
connection with other types of steel and iron alloys, and for other metals
and alloys, such as with copper or bronze for example. It can also be used
when cleaning any discolouration or tarnish from metals or alloys that result
from causes apart from welding.
The invention can also be applied to general cleaning of tarnish and
oxidation from metal surfaces that have been discoloured through natural
processes and general use. For instance, in the food industry there is a
need to keep stainless steel or other metal surfaces, containers, conduits
and the like spotless and with a mirror finish. The present invention can be
used for this purpose, either with or without the electro-cleaning apparatus
which is a preferred method of utilisation and application.
BEST MODES FOR CARRYING OUT THE INVENTION
The composition of the invention is preferably in the form of a neutralised
aqueous solution of an acid, where the acid is preferably an phosphorous
oxo acid, preferably orthophosphoric acid, or a combination of these. Of the
3- 2-
anions of orthophosphoric acid, the PO salt is preferred, but the HPO
and the H PO are also preferred, and all three anions will generally exist in
equilibrium. Additionally, other phosphoric acids, including the various
polyphosphoric acids may be used. However, other acids, such as nitric
acid, sulfuric acid, hydrochloric acid, citric acid or the like may be used.
Preferably the solution has a pH of from 6 to 8, and most preferably it has a
pH of around 7, and ideally in the range of from 6.8 to 7.2.
Preferably, the neutral solution is a salt of the acid, especially the
potassium, sodium, ammonium, magnesium, manganese or the like salts,
and most preferably is the potassium salt, or a mixture of potassium and
sodium. These salts may be introduced to the composition as a hydroxide,
which will react with the acids present. Other bases may be used, including
those that react with the acid and leave no anion component behind, such
as carbonates which produce carbon dioxide gas and water after reacting
with the acid, for example. Alternatively, the salt may be added as is to the
water present and dissolved. The components may be added both as a salt
and as an acid or base, especially if there is a need to fine tune the pH of
the resulting composition.
The amount of acid salt present in the cleaning solution is preferably from
% to 60% by weight, and more preferably in the range from 30% to 40%
by weight. When the acid salt is potassium phosphate, preferably it is
present in an amount of 30% to 40% and most preferably as about 35% by
weight. If other acid salts are used, then amounts are adjusted
proportionally to the reference of K PO . More than one acid salt may be
present. Additionally, the cleaning solutions of the invention may also be
provided in more concentrated forms, to be further diluted by the user
before actual use.
It is preferred that the weld cleaning fluid composition should contain a
chelating agent or a sequestering agent. One example of a preferred such
agent is EDTA (ethylenediaminetetraacetic acid) and especially its sodium or
potassium salts. Other suitable sequestering agents include other members
of the polyaminocarboxylic acid family of agents, particularly the
alkylenepolyaminepolycarboxylic acids and their salts. Other example
include, EGTA (ethylene glycol tetraacetic acid), BAPTA (1,2-bis(o-
aminophenoxy)ethane-N,N,N',N'-tetraacetic acid), and DTPA (diethylene
triamine pentaacetic acid).
When a sequestering agent is present, it is preferably in the aqueous
composition in an amount of from 0% to 20%, and most preferably from
about 4% to 10%. When the tetra-sodium salt of EDTA (Na EDTA) is used
as a sequestering agent, it is present as an amount preferably from 4% to
10% and most preferably in an amount of about 6-7%, by weight. When
the di-potassium salt of EDTA (K H EDTA) is used as a sequestering agent,
it is present as an amount preferably from 4% to 10% and most preferably
in an amount of about 5-6%, by weight. If other sequestering agents are
used, the quantities are adjusted generally accordingly with reference to the
preferred amount of Na EDTA. Combinations of more than one sequestering
or chelating agent may be used. If the sequestering agent(s) chosen for
inclusion should themselves be acidic or basic (ie, alkaline) in nature, then
the pH of the resulting solution can be adjusted by altering the amount of
phosphoric (or other) acid, or of the potassium hydroxide (or other) base or
of any of the pH altering components present, so that the overall pH of the
composition is around 7.
When a sequestering agent is present it functions to mop up the metal
atoms liberated from the cleaning process, to stop them recombining with
the surface of the stainless steel, and so as to remove the impurities that
cause the unwanted discolouration.
The cleaning liquid of the invention may optionally include dyes or
perfumes. Dyes are desirable to help distinguish the cleaning liquid from
other similar liquids, and to prevent users from confusing the cleaning liquid
from beverages, for example. Perfumes are helpful in disguising the
sometimes unpleasant fumes that are given off from the electro-cleaning
process, and also assist in preventing confusion with other liquid products.
One example of a suitable perfume is a “cherry blossom” fragrance that is
available from Risdon International Pty Ltd, of Yennora NSW Australia. One
example of a suitable colouring dye is the Ensitech dye #3, prepared by
Ensitech Pty Ltd, which is based on red dye. Any other suitable known dyes
or colouring agents, or perfumes may be used, especially those that are
generally known for use in cleaning products. Those dyes and perfumes that
do not chemically react with the other components are especially desirable
for use in the cleaning liquids. Also, dyes (or perfumes) that do not react
with stainless steel, or bond to the metals present, especially at high
temperatures, are strongly desirable. Also, dyes that do not stain clothing
or skin are preferred, as well as those which are easily washed away with
water. Combinations of more than one of the suitable dyes and/or perfumes
may also be employed.
When a dye is present, it generally should be present in an amount of from
0.0001% to 1%, and more preferably from about 0.005% to 0.02%, and
most preferably about 0.01%. The amount of dye should be selected to give
a reasonably visible tint to the cleaning liquid. When perfume is present, it
generally should be present in an amount of from 0.0001% to 2%, and
more preferably from about 0.01% to 0.04%, and most preferably about
0.025%. The amount of perfume to be added is selected to provide a
noticeable odour when used, especially one that will function to disguise or
ameliorate the fumes generated in the cleaning process.
The amount of dye should be selected to give a visible tint to the cleaning
liquid. Different tints or intensities of tinting may be used to distinguish
different formulations or concentrations of components. The amount of
perfume present will depend on the actual fragrance used, and its intensity.
Scents that can help disguise the fumes from the cleaning process, or that
do not interact disagreeably with such fumes are desirable. Perfumes that
are easily washed away, and that quickly dissipate are also advantageously
chosen for use in the invention.
The composition may preferably be in the form of a dilute solution of the
acid salt in water. However, it may be provided in a concentrated form
which is diluted further before use. Alternatively, the composition may be
provided to users as dry components that will be mixed with water and
dissolved prior to use. But it is preferred to provide the cleaning solution in
bottles already mixed with water, in the preferred concentration of
components for actual use. The liquid may be conveniently provided in 1
litre or 5 litre bottles, for example.
Alternatively the composition of the invention may be in the form of a paste
or gel, which may or may not be further diluted or dissolved before use. A
gel or paste form of the cleaning fluid may be used advantageously in
situations where the steel surfaces that need cleaning are oriented so that
the fluid would otherwise run off, or where unwanted drips or spillage would
present a problem.
The solvent used in the cleaning solution of the invention is water. However
other solvents may optionally also be present, especially those that readily
dissolve in water, and which permit the solution to act as an electrolyte.
Normal tap water is generally suitable for use. Alcohols may be utilised as
additional solvents, such as ethanol, methanol or propanol, for example.
Additional solvents may be utilised so as to improve the ability of the other
components to remain dissolved in the water, or to improve the washing
and drying steps after their use on the metal. The solvent system utilised
would permit the cleaning liquid to function as an electrolyte. Gelling agents
may be present in order to provide the formulation as a gel or paste.
Other optional components may be present, including surfactants, or pH
adjusting agents. Additionally, corrosion inhibitors may be included in the
composition, especially those based on ethylenediamine or imidazoline
derivatives.
The compositions of the present invention are generally prepared by
dissolving the components into the water, and adjusting the quantity of
water to bring the liquid to the preferred concentration for use.
One preferred approach is to dissolve the acid in a large quantity of water
first. Then a neutralising base is added, until the pH is about 7, with this
also preferably dissolved in water. The chemical reaction of neutalising an
acid with an alkali is often an exothermic reaction, and can be violently
exothermic, and so care must be taken, and normally the combination is
carried out slowly with mechanical agitation of the mixture. Cooling
measures can be applied as well. Then the other components may be added
to the liquid. Once the liquid is cooled, it is then bottled or otherwise
packaged. Another approach that can be used is to start from the acid salt,
such as with tripotassiumphosphate, and dissolve that directly into water,
and then add the other components.
Another alternative is to manufacture a composition by dissolving KH PO ,
K HPO and Na HPO or NaH PO and KH PO in water.
2 4 2 4 2 4 2 4
When EDTA is present, this also affect the pH and the anions present. When
the components are dissolved and mixed together various reactions will
occur. There is likely to be some neutralisation of the EDTA with KOH to
form K EDTA as well as neutralisation of H PO with KOH which follows a
2 3 4
neutralisation sequence as the KOH is consumed. The more KOH that is
present, the more dissolved K PO there will be present. Ideally there
should be three mole of KOH for every mole of H PO , in order to have
K PO . But there will also be some OH consumed in the reaction with the
EDTA. The neutralisation sequence will operate as follows:-
Sequential neutralisation steps for reacting H PO with KOH.
H3PO4 + KOH KH2PO4 + H20
KH PO + KOH K HPO + H 0
2 4 2 4 2
K HPO +KOH K PO + H 0
2 4 3 4 2
Sodium EDTA neutralisation with H PO
4 H PO + Na EDTA 4 NaH PO + EDTA
3 4 4 2 4
As KOH is added the following reactions occur:
H PO + KOH KH PO4 + H 0. (Approx pH 4.3)
3 4 2 2
EDTA + 2KOH K EDTA (5% solution gives a pH of 4-5)
At this point we would have: 0.19 moles K EDTA (70g/l as anhydrous)
0.78 mole NaH PO (93.6g/l as anhydrous)
2.17 mole KH PO (295.3g/l as anhydrous)
2 mole KOH (112.22g/l)
The KOH will react with the KH PO to form K HPO and probably some
2 4 2 4
Na HPO .
The reaction may run out of OH ions and stops before reaching the
equivalent of 100% of K PO being present, because of the consumption of
OH ions by the EDTA. Therefore the composition will have a variety of salts
in equilibrium in addition to the K PO . These include NaH PO , KH PO ,
3 4 2 4 2 4
K HPO , K PO , and K EDTA, for example. There preferably will be no free
2 4 3 4 2
KOH remaining, or if there is then any KOH left over can make some K PO .
It will be appreciated that these anions and cations will be in solution in the
water, and so the salts are only identifiable as such if it is desired to
prepare the compositions from the salts themselves, rather than by
neutralisation of the acid and base moieties.
Example 1
A composition for use as a weld cleaning liquid was prepared as follows.
Component % by weight (Total = 100%)
Phosphoric acid (H PO ) 25 %
Water ~ 58.7 %
Potassium hydroxide (KOH) 10 %
Sequestering agent (Na EDTA) 6.3 %
Fragrance (Risden Cherry Blossom) 0.025 %
Colouring (Ensitech Dye 3) 0.01 %
This formulation was prepared by dissolving the required amount of
phosphoric acid in water; tap water was used. Then the potassium
hydroxide was added gradually with stirring; this reaction is exothermic,
and care must be taken to not allow the solution to heat up too vigorously
or quickly. The sodium EDTA was then added, along with the colouring and
fragrance components. The pH of the resulting solution was tested to be a
pH of 7. The resulting liquid composition is bottled in 1 litre and 5 litre
bottles for eventual use.
The amount of potassium hydroxide may be varied, to ensure that the pH of
the final product is 7.
Example 2
A composition for use as a weld cleaning liquid was prepared as follows.
Component % by weight (Total = 100%)
Phosphoric acid (H PO ) (75% w/w) 28.3 %
Sequestering agent (Na EDTA 4.H O) 6.3 %
4. 2
Potassium hydroxide (KOH) (50 % w/w) 37.6 %
Water ~ 28.3 %
Fragrance (Risden Cherry Blossom) 0.025 %
Colouring (Ensitech Dye 3) 0.01 %
This formulation was prepared by dissolving the required amount of
phosphoric acid in tap water. The Na EDTA and then the KOH components
were added gradually with stirring. The reaction is exothermic, and care
must be taken to not allow the solution to heat up too vigorously or quickly.
The pH of the resulting solution was adjusted to have a pH of between 6.8
to 7. The colouring and fragrance components were then added. The
resulting liquid composition is bottled in 1 litre and 5 litre bottles for
eventual use.
The amount of potassium hydroxide may be varied, to ensure that the pH of
the final product is 6.8 to 7. This depends on the concentration of actual
KOH in the KOH flake or liquid which varies between manufacturers.
Example 3
Another composition for use as a weld cleaning liquid was prepared as
follows.
Component % by weight (Total = 100%)
Sodium diHydrogen Orthophosphate (NaH PO ) 6.8 %
Potassium diHydrogen Orthophosphate (KH PO ) 21.7 %
Sequestering agent (K H EDTA 4.H O) 5.6 %
2 2. 2
Potassium hydroxide (KOH) (70 % w/w) 16.5 %
Water ~ 49.4 %
Fragrance (Risden Cherry Blossom) 0.002 %
Colouring & Fragrance 0.01 %
This formulation was prepared by dissolving the required amount of the
orthophosphate salts in tap water. Into this the sequestering agent and
then the KOH components were added gradually with stirring. The pH of the
resulting solution was adjusted to have a pH of 7. The colouring, red and
yellow dye, and fragrance components were then added. The resulting liquid
composition is bottled in 1 litre and 5 litre bottles for eventual use.
The amount of potassium hydroxide may be varied, to ensure that the pH of
the final product is 6.8 to 7. The actual amount required depends on the
concentration of actual KOH in the KOH flake or liquid used, which can vary
between manufacturers.
Example 4
The compositions of the invention were tested to determine their efficacy in
cleaning and passivating stainless steel welds in accordance with suitable
Standards. The weld cleaning composition was used with Ensitech’s TIG
Brush to clean samples of 316 and 445 stainless steel.
The formulation of Example 2 was used, and tested in accordance with
ASTM Standard A967-05 “Chemical Passivation Treatments for Stainless
Steel Parts”. Practice 14, 17 and 18 were used as the most appropriate
guide for determining the performance of the weld cleaning fluid of the
invention. Additionally, the fluid was tested in accordance with ATSM
Standard B912-02 “Passivation of Stainless Steels using Electopolishing”,
because its Section 6 test procedures call for the same tests as in ATSM
A967-05.
Multiple samples were tested according to the Standard, and all treatments
were performed in triplicate. Both welded (TIG welded) and unwelded
samples were treated and tested for both 316 and 445 stainless steel. Both
the 316 and 445 stainless steel were tested for passivation according to
ASTM A967-05 Practice A – Water Immersion Test. The 316 samples were
tested for passivation as per ASTM A967-05 Practice E, Potassium
ferricyanide – nitric acid test and a ferrous sulfate spike was added to a
blank piece of 316 stainless steel acting as a positive control. The 445
samples were tested for passivation as per ASTM A967-06 Practice D –
Copper Sulfate Test. A conventional weld cleaning fluid, consisting
essentially of a 50% solution of phosphoric acid in water was also tested as
a positive control.
The formulation according to the present invention performed exceptionally
well, and passed all the ATSM tests for passivation. All the welded 316
samples cleaned according to the present invention showed no signs of
corrosion in the water immersion test, and negative results for free iron in
the potassium ferricyanide – nitric acid test. All the welded 445 samples
cleaned according to the invention showed no signs of corrosion in the
water immersion test, and negative results for free iron in the copper
sulfate test.
The term "comprises/comprising" when used in this specification is taken to
specify the presence of stated features, integers, steps or components.
However, the term does not preclude the presence or addition of one or
more additional features, integers, steps or components or groups thereof.
It will be apparent that obvious variations or modifications may be made
which are in accordance with the spirit of the invention and which are
intended to be part of the invention, and any such obvious variations or
modifications are therefore within the scope of the invention. Although the
invention is described above with reference to specific embodiments and
examples, it will be appreciated by those skilled in the art that it is not to be
limited to just those embodiments.
INDUSTRIAL APPLICABILITY
The invention can be utilised in the welding industry to clean weld tinting
from stainless steel, and to polish stainless steel welds and surfaces. It is
also useable for cleaning metal surfaces in other situations.
Claims (27)
1. A metal cleaning composition comprising an aqueous solution having a pH that is approximately neutral, said aqueous solution having from 10% to 60% by weight of a salt of an acid selected from one or more of a phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, or citric acid, and having up to 20% by weight of a salt of a polyaminocarboxylic acid as a sequestering or chelating agent.
2. The metal cleaning composition of claim 1, wherein the metal is tint welded stainless steel.
3. The composition of claim 1, wherein the acid is a phosphoric acid.
4. The composition of claim 3, wherein the acid is ortho phosphoric acid.
5. The composition of claim 1 wherein the salt of the acid is selected from any one or more of potassium, sodium, ammonium, manganese or magnesium salts.
6. The composition of claim 5 wherein the salt of the acid is the potassium salt and/or sodium salt.
7. The composition of claim 1, wherein the salt of the acid is one or more of K PO , K HPO , KH PO , and NaH PO . 3 4 2 4 2 4 2 4
8. The composition of claim 1, wherein the salt of the acid is substantially tripotassium phosphate (K PO ).
9. The composition of claim 7 wherein the salt of the acid is present in an amount of from 30% to 50% by weight of the aqueous solution.
10. The composition of claim 7 wherein the salt of the acid is present in an amount of about 35% by weight.
11. The composition of claim 1, wherein the polyaminocarboxylic acid is selected from an alkylenepolyamine polycarboxylic acid, EDTA, EGTA, BAPTA, or DTPA.
12. The composition of claim 11, wherein the salt of the polyaminocarboxylic acid is a sodium and/or potassium salt of EDTA (ethylenediaminetetraacetic acid).
13. The composition of claim 12, wherein the salt of the polyaminocarboxylic acid is tetrasodium EDTA (Na EDTA).
14. The composition of claim 1, wherein the salt of the polyaminocarboxylic acid is present in an amount of from 4% to 10% by weight of the aqueous solution.
15. The composition of claim 1, wherein the composition includes at least one fragrance and/or colouring agent.
16. The composition of claim 1, wherein the pH is between 6 and 8.
17. The composition of claim 16, wherein the pH is between 6.8 and 7.2.
18. A method of cleaning or passivating a metal surface comprising the steps of: applying a low voltage high ampage electrical current to the metal being the anode, and wiping the surface with a conductive wand or brush being the cathode, in a circuit, whereby an electrolytic fluid is applied to the surface in contact with the wand or brush; characterised in that the electrolytic fluid comprising an aqueous solution with a pH that is approximately neutral, the aqueous solution having from 10% to 60% by weight of a salt of an acid selected from one or more of a phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, or citric acid, and having up to 20% by weight of a salt of a polyaminocarboxylic acid as a sequestering or chelating agent.
19. The method of claim 18, wherein the metal surface is cleaned to remove weld tint from stainless steel.
20. The method of claim 18, wherein the metal surface is electropolished.
21. The method of claim 18, wherein the salt of the acid is selected from any one or more of K PO , K HPO , KH PO , and NaH PO . 3 4 2 4 2 4 2 4
22. The method of claim 18, wherein the salt of the acid is tripotassium phosphate (K PO ).
23. The method of claim 18, wherein the polyaminocarboxylic acid is selected from an alkylenepolyamine polycarboxylic acid, EDTA, EGTA, BAPTA, or DTPA.
24. The method of claim 23, wherein the salt of the polyaminocarboxylic acid is a sodium and/or potassium salt of EDTA.
25. The method of claim 18, wherein the electrolytic fluid contains at least one colouring agent and/or a fragrance.
26. The method of claim 18, wherein the pH is between 6 and 8.
27. The method of claim 18, wherein the pH is between 6.8 and 7.2. * * * * *
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2011903778A AU2011903778A0 (en) | 2011-09-15 | Weld Cleaning Fluid | |
AU2011903778 | 2011-09-15 | ||
PCT/AU2012/001098 WO2013036999A1 (en) | 2011-09-15 | 2012-09-14 | Weld cleaning fluid |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ622478A NZ622478A (en) | 2015-01-30 |
NZ622478B2 true NZ622478B2 (en) | 2015-05-01 |
Family
ID=
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