CA1167605A - Shielding paste for welding and especially underwater welding - Google Patents
Shielding paste for welding and especially underwater weldingInfo
- Publication number
- CA1167605A CA1167605A CA000381706A CA381706A CA1167605A CA 1167605 A CA1167605 A CA 1167605A CA 000381706 A CA000381706 A CA 000381706A CA 381706 A CA381706 A CA 381706A CA 1167605 A CA1167605 A CA 1167605A
- Authority
- CA
- Canada
- Prior art keywords
- welding
- arc
- weight
- paste
- shielding paste
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000003466 welding Methods 0.000 title claims abstract description 72
- 239000000126 substance Substances 0.000 claims abstract description 24
- 229910052739 hydrogen Inorganic materials 0.000 claims abstract description 12
- 239000001257 hydrogen Substances 0.000 claims abstract description 12
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims abstract description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 10
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims abstract description 10
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims abstract description 5
- 235000011187 glycerol Nutrition 0.000 claims abstract description 5
- 239000011777 magnesium Substances 0.000 claims abstract description 5
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 5
- WRIDQFICGBMAFQ-UHFFFAOYSA-N (E)-8-Octadecenoic acid Natural products CCCCCCCCCC=CCCCCCCC(O)=O WRIDQFICGBMAFQ-UHFFFAOYSA-N 0.000 claims abstract description 4
- LQJBNNIYVWPHFW-UHFFFAOYSA-N 20:1omega9c fatty acid Natural products CCCCCCCCCCC=CCCCCCCCC(O)=O LQJBNNIYVWPHFW-UHFFFAOYSA-N 0.000 claims abstract description 4
- QSBYPNXLFMSGKH-UHFFFAOYSA-N 9-Heptadecensaeure Natural products CCCCCCCC=CCCCCCCCC(O)=O QSBYPNXLFMSGKH-UHFFFAOYSA-N 0.000 claims abstract description 4
- ZQPPMHVWECSIRJ-UHFFFAOYSA-N Oleic acid Natural products CCCCCCCCC=CCCCCCCCC(O)=O ZQPPMHVWECSIRJ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 239000005642 Oleic acid Substances 0.000 claims abstract description 4
- 235000021314 Palmitic acid Nutrition 0.000 claims abstract description 4
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 4
- QXJSBBXBKPUZAA-UHFFFAOYSA-N isooleic acid Natural products CCCCCCCC=CCCCCCCCCC(O)=O QXJSBBXBKPUZAA-UHFFFAOYSA-N 0.000 claims abstract description 4
- ZQPPMHVWECSIRJ-KTKRTIGZSA-N oleic acid Chemical compound CCCCCCCC\C=C/CCCCCCCC(O)=O ZQPPMHVWECSIRJ-KTKRTIGZSA-N 0.000 claims abstract description 4
- 239000011574 phosphorus Substances 0.000 claims abstract description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 3
- IPCSVZSSVZVIGE-UHFFFAOYSA-N hexadecanoic acid Chemical compound CCCCCCCCCCCCCCCC(O)=O IPCSVZSSVZVIGE-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 4
- WQEPLUUGTLDZJY-UHFFFAOYSA-N n-Pentadecanoic acid Natural products CCCCCCCCCCCCCCC(O)=O WQEPLUUGTLDZJY-UHFFFAOYSA-N 0.000 claims description 3
- OYHQOLUKZRVURQ-NTGFUMLPSA-N (9Z,12Z)-9,10,12,13-tetratritiooctadeca-9,12-dienoic acid Chemical compound C(CCCCCCC\C(=C(/C\C(=C(/CCCCC)\[3H])\[3H])\[3H])\[3H])(=O)O OYHQOLUKZRVURQ-NTGFUMLPSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- 239000004411 aluminium Substances 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- TUNFSRHWOTWDNC-HKGQFRNVSA-N tetradecanoic acid Chemical compound CCCCCCCCCCCCC[14C](O)=O TUNFSRHWOTWDNC-HKGQFRNVSA-N 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 25
- 235000021355 Stearic acid Nutrition 0.000 abstract description 2
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 abstract description 2
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 abstract description 2
- 239000008117 stearic acid Substances 0.000 abstract description 2
- 235000021313 oleic acid Nutrition 0.000 abstract 1
- 150000002943 palmitic acids Chemical class 0.000 abstract 1
- 238000000034 method Methods 0.000 description 26
- 238000001816 cooling Methods 0.000 description 10
- 239000007789 gas Substances 0.000 description 10
- 239000002893 slag Substances 0.000 description 9
- 101100537937 Caenorhabditis elegans arc-1 gene Proteins 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 239000010410 layer Substances 0.000 description 5
- 239000000155 melt Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 230000035515 penetration Effects 0.000 description 2
- 239000011241 protective layer Substances 0.000 description 2
- TWJNQYPJQDRXPH-UHFFFAOYSA-N 2-cyanobenzohydrazide Chemical compound NNC(=O)C1=CC=CC=C1C#N TWJNQYPJQDRXPH-UHFFFAOYSA-N 0.000 description 1
- OYHQOLUKZRVURQ-HZJYTTRNSA-N Linoleic acid Chemical compound CCCCC\C=C/C\C=C/CCCCCCCC(O)=O OYHQOLUKZRVURQ-HZJYTTRNSA-N 0.000 description 1
- 235000021360 Myristic acid Nutrition 0.000 description 1
- TUNFSRHWOTWDNC-UHFFFAOYSA-N Myristic acid Natural products CCCCCCCCCCCCCC(O)=O TUNFSRHWOTWDNC-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 235000019628 coolness Nutrition 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000009189 diving Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000003517 fume Substances 0.000 description 1
- 230000009931 harmful effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- OYHQOLUKZRVURQ-IXWMQOLASA-N linoleic acid Natural products CCCCC\C=C/C\C=C\CCCCCCCC(O)=O OYHQOLUKZRVURQ-IXWMQOLASA-N 0.000 description 1
- 235000020778 linoleic acid Nutrition 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 229910001392 phosphorus oxide Inorganic materials 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K9/00—Arc welding or cutting
- B23K9/013—Arc cutting, gouging, scarfing or desurfacing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/3612—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest with organic compounds as principal constituents
- B23K35/3618—Carboxylic acids or salts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/38—Selection of media, e.g. special atmospheres for surrounding the working area
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Nonmetallic Welding Materials (AREA)
- Arc Welding In General (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A shielding paste for use in welding contains a base substance containing glycerin mixed with oleic acid, stearic acid and palmitic acids; amorphous phosphorus or magnesium as an illuminant; and iron oxide or magnesium for the removal of hydrogen. The invention presents improved characteristics particularly suitable for welding preformed in water.
A shielding paste for use in welding contains a base substance containing glycerin mixed with oleic acid, stearic acid and palmitic acids; amorphous phosphorus or magnesium as an illuminant; and iron oxide or magnesium for the removal of hydrogen. The invention presents improved characteristics particularly suitable for welding preformed in water.
Description
11~ 5 Shielding paste for welding and especially underwater welding The present invention concerns a shielding paste for use in arc welding and especially in underwater welding.
Undertakings that carry out welding work and manufacture weld-ing equipment and supplies have attempted to achieve, for their own use and/or to offer for sale, a welding method and equip-ment which would enable welding to be performed independent of external conditions. It is generally recognized that arc weld-ing, especially the gas-shielded method which is simple to use in good external conditions, is not successful in windy, draughty, rainy and/or damp conditions, not to mention the conditions in underwater welding.
Underwater welding has been the ~ubject of growing interest and development work in recent years. Underwater welding has been used princ~pally in repair work on drilling platforms, under-water gas and oil pipelines, ships and habour installations.
The structures welded have generally been such that it would be impossible or prohibitively expensive to raise them to the surface.The aim in underwater welding has been to achieve welds of high quality.
Known methods of carrying out welding underwater may be divided according to ,the welding environment into two main groups: wet methods and dry methods. Known wet methods using stick welding generally employ ordinary welding electrodes which have been given a waterprood coating of vinyl paint or paraffin wax to E
.~. ,,~
. ~.~
prevent them getting wet. In wet methods using a gas-shielded arc, besides the conventional equipment a welding tool is used in which a jet of water is projected in the form of a hollow cone from an outer annular orifice in order to keep the water out of the region of the arc. A water jet has been used with rela-tively good results in the C02 wet method. In wet methods, as implied by the name, the water has unhindered access to the region of the arc. In dry methods the water is prevented from reaching the region of the arc by covering it with a welding guard which is essentially closed (although, of course, the joint being welded must be left clear) or else open at the bottom, and which may be either transparent or opaque. With welding guards that are open at the bottom the welding tool is generally inserted from below; with the small, completely enclosed type, the tool is inserted through the wall. If the welding guard is sufficiently large the welder can work inside it. The atmosphere inside the guard may be either a shielding gas or air.
In underwater welding by dry methods almost the same quality of welding can be achieved, at least at small depths, as when welding in air out of the water. The dry methods, however, suffer from the drawbacks that fixing the welding guard in place and moving it are time-consuming, and tha~ welding with a guard is an inconvenient and inflexi~le process. Moreover, in many places it is not possible to use a welding guard.
Wet welding, with which this invention is concerned, is a very flexible and economic way of carrying out underwater welding work. It can be carried out using, apart from the necessary diving gear, the same equipment as is used for welding on land.
The weld quality achieved by wet methods, however, does not approach the results obtained by dry methods. Three factors ~ 2-.' -- .1 1~ ~'7~ ~ 5 detrimentally affect the quality of the weld, and each of them is a consequence of the surrounding water. They are high cool-ing rate, high hydrogen content, and the ambient pressure, which particularly at greater depths affects the reactions occurring in the arc and the deposit of material, and also affects the the reactions between the melt and the slag.
The most serious problem in wet methods is the occurrence of hydrogen-induced cracks, which is the result of the high hydrogen content which is taken up by the welded join. The problem is worsened by the high cooling rate, which reduces the diffusion of hydrogen out of the welded join, and the impracticability of using pre-hea~ing or after-heating for the removal of hydrogen, stress reduction or the avoidance of brittle microstructure. As a consequence of the high cooling rate, structural steels frequently develop a microstructure with high internal stresses and a tendency to embrittlement.
-2a-,, . _ . _ __ . . . .
~ '7~ U S
Another significant problem in the wet methods is the poor impact strength of the welded joint. The ambient pressure, especially at greater depths, affects the conditions of the slag reactions. Moreover, the rapid cooling means that the kinetic preconditions for sufficient cleansing of the weld material are not met.
Especially in rod welding by the wet method, the avoidance of weld defects such as porosity, slag inclusions, slag line.and hoint or root defects requires great skill while working under difficult conditions.
The purpose of the shielding paste of the invention is to eliminate the drawbacks hitherto a~sociated with wet methods of welding and to achieve a shielding paste which is suitable for arc welding performed in water or other liquid and in air.
Characteristics of the invention are presented in the appended list of claims.
In general terms, the present invention provides a shielding paste for underwater welding, comprising ~a) glycerin and (b) a base substance mixed with the glycerin and containing (i) 41 to 60 percent by weight of oleic acid, ~ii) 20 to 30 percent by weight of palmitic acid, and (iii) an additional acid selected from the group consisting of 1 to 10 percent by weight of linoleic acid, 1 to 4 percent by weight of myristic acid, and mixtures thereof.
The illuminant can be phosphorus and iron oxide can be used for .. ..... . . . .
the removal of hydrogen. Magnesium can be used both as an illuminant and for the removal of hydrogen.
A little aluminium powder can be mixed in the shielding paste when welding stainless steel and using austenitic electrodes.
In the recommended form of application of the invention the base _ontains 41-60% by weight of oleic acid, 8-21% by weight of stearic acid and 20-30% by weight of palmitic acid. In .,, ..~
f ~6~5 addition it may contain 1-4% by weight of myristic acid and/or 1-10~ by weight of linoleic acid.
The amount of amorphous phosphorus used as an illuminant is dependent on the depth of working and visibility, but is gener-ally about 2-10~ by weight of the base.
A suitable amount of the iron oxide used for the removal of hydrogen is about 4-6~, for example 5%, of the weight of the base. Magnesium can be used both as an illuminant and for the removal of hydrogen, in which case the amount present is suit-ably about 5-15% of the weight of the base.
By a substance introduced into the region of the arc and/or by a substance which together with water forms a liquid, fluid mixture, solution or such like which conducts electricity, an attempt is made to facilitate the controlled burning of the arc, to achieve a larger weld melt, to retard the cooling of the weld and to limit the direct presence of water in the re-gion of the arc and its contact with the weld melt.
Due to the invention electrically conducting material in the region of the arc facilitates the striking of the arc and its burning in water. On burning it forms a shielding gas zone, preventing water from reaching the arc and the melt. Such a shielding gas zone is formed especially when using organic sub-stances. Moreover it forms a layer of slag, which protects the melt from ~he action of the water when there is so much of the substance that it is not entirely consumed in the arc. This additional layer of slag formed by the substance retards the cooling of the weld and thereby improves the separation of gases from the weld. Due to the slower cooling is is easier . . .
, .~f . . _ . . _ to obtain a satisfactory weld shape. The substance affects the melting speed and penetration. The melting speed and penetration are improved particularly when using organic substances, which on burning in the arc produce considerable quantities of thermal energy.
In welding tests with shielding paste according to the invention, excellent results have been achieved. The reasons for this are not fully understood. Another factor retarding the cooling of the weld, in addition to the protective effect of the auxiliary substance, could be that as a consequence of the use of the auxiliary substance electrical currents are formed outside the actual arc, between the electrode and the whole of the object being welded, thereby heating the object, water which may possi-bly be in its vicinity, and the weld seam together with the slag layer and the additional layer of slag. The weld would then remain hot longer, improving the escape of hydrogen and thus reducing hydrogen-embrittlement, with a resulting strengthening of the weld seam.
Welding performed underwater with the shielding paste of the invention can be classed as a wet method, because the water together with possible additives has almost unrestricted access to the region of the arc. The method is suitable for use with all types of arc and gas arc welding methods, such as rod (stick, SMA) welding, MIG, MAG, TIG (GTA), Arcatom*and plasma welding.
The e~uipment and apparatus required vary according to the welding method chosen.
The description given below is primarily concerned with under-water welding, because arc welding underwater currently pre-sents the greatest problems. Nevertheless, it is possible to * a tr~d~mark ~ , .. . . . .. . ..
7~S
use the method for arc welding performed in other external con-ditions, for example in connection with arc welding which is performed in air. In this case the electrically conducting sub-stance~ and/or the substance which together with water forms an electrically conducting liquid, fluid mixture, solution or such like prevents the harmful effects of air as well as water on the weld. When the shielding paste is used in connection with arc welding performed in air, the formation of fumes is greater than when it is used in connection with underwater welding. In this connection mention may be made of an application of the invention in which the normal shielding gas used in arc welding is replaced by a paste which protects both the arc and the weld. The paste is extremely suitable for use in connection with arc welding performed in both water and air, the paste protecting both the arc and the weld.
Methods of use of the paste according to the invention are des-cribed in the following with reference to the drawings, in which:
Figure 1 is a diagrammatic representation of the introduction of the paste according to the present invention into the region of the welding arc;
Figure 2 shows, in diagrammatic way, the introduction of the paste to the region of the arc via an annular nozzle surrounding the welding electrode;
Figure 3 is a representation in which the arc which is formed between the welding electrode and the base material is partially protected by the paste according to the present invention: and Figure 4 shows the application of the paste according to the invention to a welding electrode.
~ -6-1~'7~i~PS
In Fic;ure 1 the arc 1 is struck between the welding electrode 9 and the base material 13. At the same time the welding electrode 9 melts and forms the weld 10, which fuses with the base material 13. As the weld 10 is formed, the coating of the welding electrode 9 creates a slag layer 11 on top of the weld.
The paste 2 according to the invention is introduced into the region of the arc 1 by an inlet 12.
In the application represented in Figure 2 the paste 2 is intro~
duced to the region 14 of the arc via an annular nozzle 4 which surrounds the welding electrode 9 and the arc 1. The paste causes the region of the arc to become electrically conducting.
This method resembles gas-shielded arc welding (MIG, MAG, TIG), but with the paste of the invention in place of the gas. The annular nozzle can, of course, extend to the filler wire. The use of shielding gas in addition to the paste is, of course, possible. The shielding gas can blow, for instance, through ~ 6a-,~. ,s,;
7t~5 the annular space between the inner jacket of the nozzle and the outer jacket of the holder of the electrode 9.
Figure 3 represents an application in which the arc 1, which is foxmed between the welding electrode 9 and the base material 13, is partially protected by a paste 3 according to the in-vention. In the region of the arc a substance is given off by the paste 3 which dissolves and makes the water in the region of the arc electrically conducting; the welding takes place under water with water surrounding the object being welded.
As the welding proceeds the paste 3 is moved along behind the arc as the weld is formed, so that the arc burns in the hollow 7 formed by-the piece of paste. The paste 3 also deposits a protective layer 8 on the weld 10. The protective layer 8 re-tards the cooling of the weld joint 10 and inhibits contact between the water and the weld joint. Furthermore, the paste 3 remaining on the hot weld joint 10, being an organic sub-stance, continues to burn even after the arc, and this is conducive to efficient prevention of excessively rapid cooling of the weld.
The application of the invention to a welding electrode 9 is represented in Figure 4. In this a conventional, ether coated or bare, welding electrode 9 is additionally coated with a paste 3 which gives off and/or dissolves in the region of the arc 1 a substance making this region electrically con-ducting. The hollow 7 can, of course, also be enclosed by the paste on the open side of the gap being bridges by welding, in which case the arc 1 is essentially in a closed space.
l.~ S
The application of the invention is not limited to the examples given above, but may vary wi$hin the scope of the accompanying patent claims. Thus, for instance, the guides for the auxiliary substance used in the welding and which are part of the welding equipment used, may consist, for example, of an annular nozzle or similar partially or preferably completely encircling the electrode rod or wire, or of one or more tubular or other nozzles or such like located in the immediate vicinity of the electrode rod or wire. Further, the auxiliary substance may be fed by means of a piston, centrifugal or diaphragm pump or other such pump or such like feeding device or other feeding device, as, for instance, a screw feeder or similar.
C
~ 8-,,,1
Undertakings that carry out welding work and manufacture weld-ing equipment and supplies have attempted to achieve, for their own use and/or to offer for sale, a welding method and equip-ment which would enable welding to be performed independent of external conditions. It is generally recognized that arc weld-ing, especially the gas-shielded method which is simple to use in good external conditions, is not successful in windy, draughty, rainy and/or damp conditions, not to mention the conditions in underwater welding.
Underwater welding has been the ~ubject of growing interest and development work in recent years. Underwater welding has been used princ~pally in repair work on drilling platforms, under-water gas and oil pipelines, ships and habour installations.
The structures welded have generally been such that it would be impossible or prohibitively expensive to raise them to the surface.The aim in underwater welding has been to achieve welds of high quality.
Known methods of carrying out welding underwater may be divided according to ,the welding environment into two main groups: wet methods and dry methods. Known wet methods using stick welding generally employ ordinary welding electrodes which have been given a waterprood coating of vinyl paint or paraffin wax to E
.~. ,,~
. ~.~
prevent them getting wet. In wet methods using a gas-shielded arc, besides the conventional equipment a welding tool is used in which a jet of water is projected in the form of a hollow cone from an outer annular orifice in order to keep the water out of the region of the arc. A water jet has been used with rela-tively good results in the C02 wet method. In wet methods, as implied by the name, the water has unhindered access to the region of the arc. In dry methods the water is prevented from reaching the region of the arc by covering it with a welding guard which is essentially closed (although, of course, the joint being welded must be left clear) or else open at the bottom, and which may be either transparent or opaque. With welding guards that are open at the bottom the welding tool is generally inserted from below; with the small, completely enclosed type, the tool is inserted through the wall. If the welding guard is sufficiently large the welder can work inside it. The atmosphere inside the guard may be either a shielding gas or air.
In underwater welding by dry methods almost the same quality of welding can be achieved, at least at small depths, as when welding in air out of the water. The dry methods, however, suffer from the drawbacks that fixing the welding guard in place and moving it are time-consuming, and tha~ welding with a guard is an inconvenient and inflexi~le process. Moreover, in many places it is not possible to use a welding guard.
Wet welding, with which this invention is concerned, is a very flexible and economic way of carrying out underwater welding work. It can be carried out using, apart from the necessary diving gear, the same equipment as is used for welding on land.
The weld quality achieved by wet methods, however, does not approach the results obtained by dry methods. Three factors ~ 2-.' -- .1 1~ ~'7~ ~ 5 detrimentally affect the quality of the weld, and each of them is a consequence of the surrounding water. They are high cool-ing rate, high hydrogen content, and the ambient pressure, which particularly at greater depths affects the reactions occurring in the arc and the deposit of material, and also affects the the reactions between the melt and the slag.
The most serious problem in wet methods is the occurrence of hydrogen-induced cracks, which is the result of the high hydrogen content which is taken up by the welded join. The problem is worsened by the high cooling rate, which reduces the diffusion of hydrogen out of the welded join, and the impracticability of using pre-hea~ing or after-heating for the removal of hydrogen, stress reduction or the avoidance of brittle microstructure. As a consequence of the high cooling rate, structural steels frequently develop a microstructure with high internal stresses and a tendency to embrittlement.
-2a-,, . _ . _ __ . . . .
~ '7~ U S
Another significant problem in the wet methods is the poor impact strength of the welded joint. The ambient pressure, especially at greater depths, affects the conditions of the slag reactions. Moreover, the rapid cooling means that the kinetic preconditions for sufficient cleansing of the weld material are not met.
Especially in rod welding by the wet method, the avoidance of weld defects such as porosity, slag inclusions, slag line.and hoint or root defects requires great skill while working under difficult conditions.
The purpose of the shielding paste of the invention is to eliminate the drawbacks hitherto a~sociated with wet methods of welding and to achieve a shielding paste which is suitable for arc welding performed in water or other liquid and in air.
Characteristics of the invention are presented in the appended list of claims.
In general terms, the present invention provides a shielding paste for underwater welding, comprising ~a) glycerin and (b) a base substance mixed with the glycerin and containing (i) 41 to 60 percent by weight of oleic acid, ~ii) 20 to 30 percent by weight of palmitic acid, and (iii) an additional acid selected from the group consisting of 1 to 10 percent by weight of linoleic acid, 1 to 4 percent by weight of myristic acid, and mixtures thereof.
The illuminant can be phosphorus and iron oxide can be used for .. ..... . . . .
the removal of hydrogen. Magnesium can be used both as an illuminant and for the removal of hydrogen.
A little aluminium powder can be mixed in the shielding paste when welding stainless steel and using austenitic electrodes.
In the recommended form of application of the invention the base _ontains 41-60% by weight of oleic acid, 8-21% by weight of stearic acid and 20-30% by weight of palmitic acid. In .,, ..~
f ~6~5 addition it may contain 1-4% by weight of myristic acid and/or 1-10~ by weight of linoleic acid.
The amount of amorphous phosphorus used as an illuminant is dependent on the depth of working and visibility, but is gener-ally about 2-10~ by weight of the base.
A suitable amount of the iron oxide used for the removal of hydrogen is about 4-6~, for example 5%, of the weight of the base. Magnesium can be used both as an illuminant and for the removal of hydrogen, in which case the amount present is suit-ably about 5-15% of the weight of the base.
By a substance introduced into the region of the arc and/or by a substance which together with water forms a liquid, fluid mixture, solution or such like which conducts electricity, an attempt is made to facilitate the controlled burning of the arc, to achieve a larger weld melt, to retard the cooling of the weld and to limit the direct presence of water in the re-gion of the arc and its contact with the weld melt.
Due to the invention electrically conducting material in the region of the arc facilitates the striking of the arc and its burning in water. On burning it forms a shielding gas zone, preventing water from reaching the arc and the melt. Such a shielding gas zone is formed especially when using organic sub-stances. Moreover it forms a layer of slag, which protects the melt from ~he action of the water when there is so much of the substance that it is not entirely consumed in the arc. This additional layer of slag formed by the substance retards the cooling of the weld and thereby improves the separation of gases from the weld. Due to the slower cooling is is easier . . .
, .~f . . _ . . _ to obtain a satisfactory weld shape. The substance affects the melting speed and penetration. The melting speed and penetration are improved particularly when using organic substances, which on burning in the arc produce considerable quantities of thermal energy.
In welding tests with shielding paste according to the invention, excellent results have been achieved. The reasons for this are not fully understood. Another factor retarding the cooling of the weld, in addition to the protective effect of the auxiliary substance, could be that as a consequence of the use of the auxiliary substance electrical currents are formed outside the actual arc, between the electrode and the whole of the object being welded, thereby heating the object, water which may possi-bly be in its vicinity, and the weld seam together with the slag layer and the additional layer of slag. The weld would then remain hot longer, improving the escape of hydrogen and thus reducing hydrogen-embrittlement, with a resulting strengthening of the weld seam.
Welding performed underwater with the shielding paste of the invention can be classed as a wet method, because the water together with possible additives has almost unrestricted access to the region of the arc. The method is suitable for use with all types of arc and gas arc welding methods, such as rod (stick, SMA) welding, MIG, MAG, TIG (GTA), Arcatom*and plasma welding.
The e~uipment and apparatus required vary according to the welding method chosen.
The description given below is primarily concerned with under-water welding, because arc welding underwater currently pre-sents the greatest problems. Nevertheless, it is possible to * a tr~d~mark ~ , .. . . . .. . ..
7~S
use the method for arc welding performed in other external con-ditions, for example in connection with arc welding which is performed in air. In this case the electrically conducting sub-stance~ and/or the substance which together with water forms an electrically conducting liquid, fluid mixture, solution or such like prevents the harmful effects of air as well as water on the weld. When the shielding paste is used in connection with arc welding performed in air, the formation of fumes is greater than when it is used in connection with underwater welding. In this connection mention may be made of an application of the invention in which the normal shielding gas used in arc welding is replaced by a paste which protects both the arc and the weld. The paste is extremely suitable for use in connection with arc welding performed in both water and air, the paste protecting both the arc and the weld.
Methods of use of the paste according to the invention are des-cribed in the following with reference to the drawings, in which:
Figure 1 is a diagrammatic representation of the introduction of the paste according to the present invention into the region of the welding arc;
Figure 2 shows, in diagrammatic way, the introduction of the paste to the region of the arc via an annular nozzle surrounding the welding electrode;
Figure 3 is a representation in which the arc which is formed between the welding electrode and the base material is partially protected by the paste according to the present invention: and Figure 4 shows the application of the paste according to the invention to a welding electrode.
~ -6-1~'7~i~PS
In Fic;ure 1 the arc 1 is struck between the welding electrode 9 and the base material 13. At the same time the welding electrode 9 melts and forms the weld 10, which fuses with the base material 13. As the weld 10 is formed, the coating of the welding electrode 9 creates a slag layer 11 on top of the weld.
The paste 2 according to the invention is introduced into the region of the arc 1 by an inlet 12.
In the application represented in Figure 2 the paste 2 is intro~
duced to the region 14 of the arc via an annular nozzle 4 which surrounds the welding electrode 9 and the arc 1. The paste causes the region of the arc to become electrically conducting.
This method resembles gas-shielded arc welding (MIG, MAG, TIG), but with the paste of the invention in place of the gas. The annular nozzle can, of course, extend to the filler wire. The use of shielding gas in addition to the paste is, of course, possible. The shielding gas can blow, for instance, through ~ 6a-,~. ,s,;
7t~5 the annular space between the inner jacket of the nozzle and the outer jacket of the holder of the electrode 9.
Figure 3 represents an application in which the arc 1, which is foxmed between the welding electrode 9 and the base material 13, is partially protected by a paste 3 according to the in-vention. In the region of the arc a substance is given off by the paste 3 which dissolves and makes the water in the region of the arc electrically conducting; the welding takes place under water with water surrounding the object being welded.
As the welding proceeds the paste 3 is moved along behind the arc as the weld is formed, so that the arc burns in the hollow 7 formed by-the piece of paste. The paste 3 also deposits a protective layer 8 on the weld 10. The protective layer 8 re-tards the cooling of the weld joint 10 and inhibits contact between the water and the weld joint. Furthermore, the paste 3 remaining on the hot weld joint 10, being an organic sub-stance, continues to burn even after the arc, and this is conducive to efficient prevention of excessively rapid cooling of the weld.
The application of the invention to a welding electrode 9 is represented in Figure 4. In this a conventional, ether coated or bare, welding electrode 9 is additionally coated with a paste 3 which gives off and/or dissolves in the region of the arc 1 a substance making this region electrically con-ducting. The hollow 7 can, of course, also be enclosed by the paste on the open side of the gap being bridges by welding, in which case the arc 1 is essentially in a closed space.
l.~ S
The application of the invention is not limited to the examples given above, but may vary wi$hin the scope of the accompanying patent claims. Thus, for instance, the guides for the auxiliary substance used in the welding and which are part of the welding equipment used, may consist, for example, of an annular nozzle or similar partially or preferably completely encircling the electrode rod or wire, or of one or more tubular or other nozzles or such like located in the immediate vicinity of the electrode rod or wire. Further, the auxiliary substance may be fed by means of a piston, centrifugal or diaphragm pump or other such pump or such like feeding device or other feeding device, as, for instance, a screw feeder or similar.
C
~ 8-,,,1
Claims (6)
1. A shielding paste for underwater welding, comprising (a) glycerin and (b) a base substance mixed with the glycerin and containing (i) 41 to 60 percent by weight of oleic acid, (ii) 20 to 30 percent by weight of palmitic acid, and (iii) an additional acid selected from the group consisting of 1 to 10 percent by weight of linoleic acid, 1 to 4 percent by weight of myristic acid, and mixtures thereof.
2. A shielding paste as claimed in Claim 1, characterized in that it contains approximately 4-6% of iron oxide, expressed as a percentage of the weight of the base substance.
3. A shielding paste in accordance with claim 1, characterized in that it contains, in addition to the base substance and expressed as a percentage of the weight of the base substance, approximately 5-15% of magnesium as an illuminant and for the removal of hydrogen.
4. A shielding paste in accordance with any of claims 1, 2 or 3, characterized in that it additionally contains aluminium powder.
5. A shielding paste in accordance with any of Claims 1, 2 or 3, containing about 5% of iron oxide, expressed as a percentage of the weight of the base substance.
6. A shielding paste as claimed in Claim 1, wherein the base substance comprises as illuminant 2 to 10 percent by weight of amorphous phosphorus.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI802244A FI67188C (en) | 1980-07-15 | 1980-07-15 | SKYDDSPASTA FOER UNDERVATTENSVAOTSVETSNING |
| FI802244 | 1980-07-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1167605A true CA1167605A (en) | 1984-05-22 |
Family
ID=8513627
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000381706A Expired CA1167605A (en) | 1980-07-15 | 1981-07-14 | Shielding paste for welding and especially underwater welding |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5739093A (en) |
| CA (1) | CA1167605A (en) |
| DE (1) | DE3128000A1 (en) |
| FI (1) | FI67188C (en) |
| FR (1) | FR2486843A1 (en) |
| GB (1) | GB2083394B (en) |
| IT (1) | IT8167973A0 (en) |
| NO (1) | NO155481C (en) |
| SE (1) | SE8104352L (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI74418C (en) * | 1985-07-24 | 1988-02-08 | Niinivaara Oy | Additive for arc welding. |
| US4804818A (en) * | 1986-09-08 | 1989-02-14 | Andersen Leonard M | Coated electrode for arc welding |
| JPS63152225A (en) * | 1986-12-17 | 1988-06-24 | Nec Corp | Atomic oscillator |
| JPS63256017A (en) * | 1987-04-13 | 1988-10-24 | Nec Corp | Rubidium atomic oscillator |
| DE4035229A1 (en) * | 1990-11-06 | 1992-05-07 | Anton Schloegel | Welding area marker - is a reflecting or fluorescent medium to give welder a better view of the workpiece through the tinted goggles or face mask |
| US5412176A (en) * | 1993-06-18 | 1995-05-02 | Massachusetts Institute Of Technology | Method and apparatus for thermal insulation of wet shielded metal arc welds |
-
1980
- 1980-07-15 FI FI802244A patent/FI67188C/en not_active IP Right Cessation
-
1981
- 1981-07-14 IT IT8167973A patent/IT8167973A0/en unknown
- 1981-07-14 CA CA000381706A patent/CA1167605A/en not_active Expired
- 1981-07-14 SE SE8104352A patent/SE8104352L/en not_active Application Discontinuation
- 1981-07-14 NO NO812416A patent/NO155481C/en unknown
- 1981-07-15 DE DE19813128000 patent/DE3128000A1/en not_active Withdrawn
- 1981-07-15 GB GB8121976A patent/GB2083394B/en not_active Expired
- 1981-07-15 FR FR8113764A patent/FR2486843A1/en not_active Withdrawn
- 1981-07-15 JP JP11152381A patent/JPS5739093A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| SE8104352L (en) | 1982-01-16 |
| JPS5739093A (en) | 1982-03-04 |
| FR2486843A1 (en) | 1982-01-22 |
| GB2083394B (en) | 1984-07-11 |
| FI67188B (en) | 1984-10-31 |
| FI67188C (en) | 1985-02-11 |
| IT8167973A0 (en) | 1981-07-14 |
| NO812416L (en) | 1982-01-18 |
| FI802244A7 (en) | 1982-01-16 |
| NO155481C (en) | 1987-04-08 |
| GB2083394A (en) | 1982-03-24 |
| DE3128000A1 (en) | 1982-07-01 |
| NO155481B (en) | 1986-12-29 |
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