METHOD, APPARATUS AND ELEMENT FOR ACCOMPLISHING AN UNDERWATER WELD JOINT

Abstract: Method, apparatus and element to be welded fast for accomplishing an underwater weld joint with a welding electrode (4) between a support (3) and an onto the support (3) brought element (1) to be welded fast. The invention is characterized in that the junction to be welded between the support (3) and the element (1) to be welded fast is insulated from the ambient water with a protection cover (9) which is disposed tigthtly against the free surface (8) of the element (1) to be welded fast and through the wall of which cover the welding electrode (1) rotating about its longitudinal axis extends is pressed during the welding operation against the edges of an opening (5) in the element (1) to be welded fast, towards the support (3).

Description: Method, apparatus and element for accomplishing an under¬ water weld Joint The invention relates to a method and apparatus far ac- cαmplishing an underωater meld joint, preferably For fix¬ ing anodes controlling the corrosion of the underwater parts off offshore constructions, in which method that surface of the support to which the element to be melded is to be Fastened is First cleaned, ωhereaFter the ωelding apparatus is secured to thr support For the melding opera¬ tion, and which apparatus comprises cleaning and Fastening means For cleaning that surface αF the support to ωhich the element is tα be melded and For securing the apparatus to the support. The invention also relates tα an element to be melded Far use with said method and apparatus. Undεr ater ωelding operations have increased intensely awing ta the Fact that various αFF-shore constructions have became mare common and especially that marine dril- ling Far ail has increased. One αF the mast signiFicant problems with such αFF-shαre constructions is the attack αF cαrrαsiαn, which, IF uncontrolled, will destroy, the construction tα be useless in a very short time. Attemps have been made to salve this problem, even with goad success, by Fixing carrasian-cantralling anodes αnto to the underwater parts. Thereby a new problem has presented itselF, the replacement αF the cαrrαded anαdes with new ones, since under ater melding is very expensive and diF- Ficult tα carry αut. Known in the art is sα-called habitat-chamber welding method used in underwater repair operations which method has also bee used For Fixing said cαrrαsiαn-cαntrαlling anodes. This known method is based on supporting the abject to be repaired or the cαrrαsiαn-cαntrαlling anαde tα be Fixed into a special chamber wherein the diver carries αut thr necessary welding operations. Althαught said habitat-chamber melding method strives at Fulfilling the quality reguiremeπts set Far the welding by diFFerent classification societies, it has the disadvantage αF being very expensive bath in running cast and in investment, since it employs a large and complicated cαnstructiαn and additionally always reguires a diver tα be present. Owing tα the expensiveness αF the habitat-chamber welding method eFFαrts have already long been made tα develop wet welding methods wherewith the quality reguirements set by the classiFication societies could be FulFilled. The greatest hindrance tα the success αF these met welding methods has been the hardening αg the steel in the underwater parts, whereby so-called hydrogen-cracks are Formed which may cram mith time and break the steel. Far this reason, e.g. Det Nαrske Ueritas has prohibited all welding methods not FulFilling thr very high reguirements For the welding quality set by this classiFication society. The abject aF the present invention is to improve, accele- rate and Facilitate underwater welding as well as tα eliminate the disadvantages and weaknesses αF all the previously known underwater welding methods. These objects have been achieved, according tα the method αF invention, in such a manner that the element tα be melded is brought αntα the cleaned support, that the Junction αF the support and the element tα be melded is insulated Frαm the ambient mass αF mater and that during the melding operation the welding electrode is pressed against the edges oF an opening extending through the element tα be welded, tα ards the support. The apparatus herewith the this method is carried αut is characterized in comprising placing means Far bringing the element ta be welded ta its Fastening paint on the cleaned support, at least one protecting cover disposed in tight relationship on the Free surFace oF the element tα be welded Fast at least for the duration oF the welding operation, through the wall αF ωhich cover at least αne welding electrode sealed with respect tα said mall ex¬ tends, hich cover insulates the junction between the element tα be melded Fast and the support Frαm the ambient mass αF water, and a drive means Far conducting welding current ta the welding electrode and Far pressing said welding electrode against the edges αF the opening in the element during the welding operation. The element tα be welded Fast by the method αF the inven¬ tion and with the apparatus αF the invention is characte¬ rized in having at least αne opening Far the melding electrode, extending through said element in a direction substantially perpendicular tα the support. The primary advantage αF the invention is that the appara¬ tus is small-sized and is αF a Far simpler construction and considerably cheaper than the apparatus used with the earlier knα n habitat-chamber melding method. A Further advantage of the invention is that it can be used totally mithout a diver: the present invention may be used For a previously undetermined period. Oming to the small size, simple construction and Faster set-up, signiFicant savings are thus obtained both in investment and running costs. The Follαming is a more detailed description of the inven¬ tion by means αF preferred empαdiments mith reference tα the accompanying dra ings, mherein Figure 1 shows the welding apparatus according tα the invention in a partial cross-section, said apparatus being secured tα an unmanned diving apparatus, and Figure 2 shams a partially cross-cut side view of the welding apparatus according tα a preFerred empodiment of the invention. In the example shown in Figure 1, the welding apparatus 20 according to the invention has been secured tα a remotely- cαntrolled unmanned diving apparatus 100 mherewith the welding apparatus is moved in the water From a welding spot tα another. Firstly, that surFace αF the support 3, said support being in this exemplary case an underωater leg oF an oil rig, against which the element 1, which in this exemplary case is a cαrrαsiαn-cαntrαlling anode, is tα be melded Fast is cleaned, and aFter cleaning the melding apparatus is secured to the abject to be melded. Far carrying αut these operations, the melding apparatus 20 has cleaning and Fastening means 21 articulated tα the remσtely-contrαlled diving apparatus 100 by means αF hyd¬ raulically movable lever arms 101 and 102. In this preFer¬ red example, the cleaning and Fastening means consists αF discs 21 preFerably αF rubber-based material and rotated by a hydraulic motor 103, said discs grinding the surFace 2 tα be under the element 1 tα be Fully clean and genera¬ ting, mhen rotating near the surFace 2 αF the support 3, a pαmεrFul subatmospheric pressure, whereby the welding apparatus 20 is Firmly secured in place awing ta the suctian eFFect produced by the subatmospheric pressure. AFter the securing αF the welding apparatus 20 in place, the element 1 tα be welded Fast is brought onto the sup- part 3, and the junction between the support 3 and the ■ element 1 to be melded Fast is insulated From the ambient mass αF water. For bringing the element 1 tα welded Fast in place, the welding apparatus 20 comprises placing means 22, ωhich in this exemplary case shown in Figure 1 consist αF hydraulically movable shears 22 Fastened tα diving apparatus. Far insulating the junction tα he welded, the welding apparatus 20 comprises a cup-like protecting cover 9 which can be transported by means oF hydraulically movable lever arms 104, 105, said protecting cover being pressed tightly about the junction to he welded, against the Free tap surFace 8 αF the element 1 tα be melded Fast. To achieve gααd sealing, the head edge 12 αF the protec¬ ting cover 9 which is tα abut the element 1 tα be welded fast is provided ωith a gasket 13. Alternatively the protecting cover 9 may be Fastened be- Fαrehand, e.g. by ωelding, αntα the surFace αF the element 1 tα be ωelded Fast tα surround the Junction tα be ωelded. For secure and Fully sealed insulation αf the Junction to be ωelded From the ambient mass oF water, a spacer ring 6 of suitable elastic material, preFerably rubber, is dispo¬ sed between the element 1 tα be welded Fast and the sup¬ port 3 tα Farm an insulated interspace 7. Tα Facilitate the Fitting, the spacer ring 6 has been Fastened in advan- ce, e.g. by glueing tα the surFace αF the element 1 to be welded Fast which is tα abut the support 3. An opening 5 Far the welding electrode 4 has been made by baring in the element 1 at the Junction tα be ωelded, said opening extending substantially perpendicularly tα the surFace 2 in the support 3. As can be seen From Figures 1 and 2, the melding electrode 4 has been arranged to protrude in a sealed manner through the mall αF the protecting cover 9, whereby the drive means 23 rotating the melding electrode 4 and pressing it downwards has been Fastened tα that part αF the welding electrode 4 which protrudes From the protecting cover 9. In this exemplary case, the drive means comprises gripping means 24 consisting αF hydraulically movable Jaws 26,27 and being Fixed tα that part oF the welding electrode 4 which protrudes From the protecting cover 9, as well as a rotating means 25, which is preFerably a hydraulic motor and which is connected in a nαn-rαtating manner tα hydrau- lically movable jaws 26,27 and which is Furnished with a screw Feeder 28 Far the welding electrode, said screw Feeder Feeding the welding electrode Forward at a speed substantially corresponding tα the speed αf cαnsumptiαπ αf the welding electrode, as well as with current-conducting carbons 29 Far conducting the ωelding current ta the welding electrode. As can be seen From the Figures 1 and 2, that part αf the ωelding electrode 4 mhich lies ithin the interior of the protecting cover 9 as mell as the opening 5 Far the ωel¬ ding electrode 4 have been Formed tα match αne another, tα taper conically downwards towards tα the support 3. Owing tα this kind αF shaping as well as rotating movement of the welding electrode 4, all welding slag will be pushed upwards into the protecting cover 9, and no slag inclu¬ sions weakening the weld joint will be Formed. To achieve a high-standard welding result, the interior 10 αF the protecting cover must be Free From water priαr tα the ' commencing αF the ωelding operation. Tα fulfil this requirement, according tα αne embodiment αF the invention the wall 11 αF the protecting cover 9 is provided with an αutFlαω member 14 connected preFerably either tα a vacuum source or a suction device. By means αF this ■ αutFlαω member 14, the interior 10 αF the protecting cover 9 can be evacuated αF ωater and also αF the ωelding gases Formed during melding operation. According tα an alternative embodiment, a suitable Filler, such as gas, pαlyuretane Foam αr welding Flux, may be injected into the interior 10 αF the protecting cover 9 tα be pressed in place, either through the open head edge 12 αr through an αutFlαw mem- her, preFerably a pressure valve 15, disposed in the wall 11 αF the protecting cover 9 and opening at a predetermi¬ ned pressure, tα evacuate water From said interior priαr tα the commencing αF the welding operation. In the latter case, the αutFlow member 15 also used tα evacuate gases Farmed in connection mith the ωelding operation From the interior 10 αF the protecting cover 9. When the protecting cover 9 has been Fastened in advance permanently tα the element 1. tα be melded Fast, the penetration αF mater into the interior 10 αF the protecting cover 9 can be prevented most simply by that the opening in the element 1 tα be melded Fast is covered with a suitable covering material, e.g. molten resin. According tα the preFerred embodiment oF the invention, the protecting resin has been applied tα the element 1 tα that surFace αF the spacer ring 6, Fitted cαaxially ωith the opening 5, ωhich is to abut the support 3. Also in this exemplary case, the mall 11 αF the prαtec- ting cover 9 is provided ωith an αutFloω member 15 αF the type shαωn in Figure 2 Far the evacuation αF the melding gases during the melding operation. As can be seen From Figure 2, the material thickness αF the melding mass in the conical part αF the melding elec¬ trode 4 is constant, and its height is preFerably dimen¬ sioned tα cαrrespαnd tα the thickness oF the element 1 tα be ωelded Fast in each case. Thanks tα this construction, certainly can be reached αF the Fact that the ωelding result ωill FulFil the present quality requirements, and the protecting cover 9 Fastened permanently in advance need not be removed Far inspection. In order ta reach certainly αF the Fact that the ωelding electrode ωill pass precisely into the opening 5 in the element 1 tα be melded Fast, the mall 11 αF the protecting cover 9 is provided mith a guide bushing 30 For the mel¬ ding electrαde 4, said bushing having a gasket Far the sealed inlet αF the ωelding electrαde 4 into the interior 10 αF the protecting cover 9. Regarding the operation αF the aparatus, it may Further be stated that a diving apparatus αr a diving robot mill independently Fetch the anodes to be Fastened From a cage lαmered in the mater, said cage containing a large number αf anodes, and bring them tα be fastened to the ωork objects. All operations αF the apparatus can be mαnitαred by means αF a monitor 107 Fastened tα the diving apparatus and provided ωith an illumination device 106. The diving apparatus may also be provided ωith an ultracamera check¬ ing also the quality αF the ωelding done through the protecting cover 9, and thus it is possible Far the moni¬ toring persons, iF necessary, tα Fαllαm the Fastening oF each anαde, as the apparatus is marking under mater. It may Further be stated that the necessary number αF hydraulic pumps are provided in the diving apparatus 100, Far marking the lever arms αF the melding apparatus as ωell as the hydraulic motor 103, and a source αF ωelding current is also provided in the diving apparatus, From ωhich source the ωelding current is conducted through the rotating means 25 to ωelding electrαde 4. In this exempla¬ ry case, the source αF ωelding current is earthed through the shears 22 tα the element 1 tα ωelded Fast. The invention has been described in the Foregoing merely by means αF same preFerred embodiments thereoF. This is by na means intended to limit the invention tα relate merely tα said exemplary cases, but, as is apparent to the man skilled in the art, the invention may be varied tα subs¬ tantial degree ωithin the scope oF the inventive concept deFined in the appended claims. It ωill be specially emphasized that the ωelding apparatus does not presuppose the use oF an unmanned diving apparatus, but it can also be applied tα a diver αr tα a manned diving carrier.

Claims: AMENDED CLAIMS [received by the International Bureau on 28 November 1985 (28.11.85) original claims 1-23 replaced by amended claims 1-23 (5 pages)] 1. A method Far accomplishing an underwater weld Joint with a wεlding εlεctrαdε C4), in which mεthαd an element Cl) tα be melded Fast is brought αntα a surFace C2) αF a support C3) tα which the elemεπt Cl) is tα be welded, c h a r a c t e r i z e d in that a Junction tα be welded betwεεn the support C3) and the element Cl) to be welded Fast is insulated Frαm the ambient water by disposing a protection cover C9) tightly against the elεment Cl) tα be welded Fast and that during the welding operation the ωel¬ ding electrod C4) , which rotates about its longitudinal axis, is led against edges αF an opening C5) in the elε¬ ment Cl) to be welded Fast, towards the support C3) . 2. A method according tα claim l c h a r a c t e r i z e d in that a sealing spacer ring C6) αF Flexible material, preFerably rubber, is disposed between the element Cl) tα be welded Fast and the support C3) tα Form an interspace C7) insulated From thε ambient mass αF water, between the element Cl) tα be welded Fast and the support C3) . 3. A method according tα claim 1 or 2, c h a r a c t e ¬ i z e d in that a preFerably cupshaped protecting cover C9) is pressed αntα the the Free surFace C8) oF thε ele¬ ment Cl) brought απtα the support C3), an tap aF the junction ta be welded, ta be in a sealed relationship with the element Cl) tα be welded Fast and tα enclose the Junction tα be welded Frαm the ambient mass αF water within the interior CIO) αF the protecting cover C9) . 4. A method according tα the claim 3, c h a r a c t e r i¬ z e in that the interior CIO) oF the protecting cover C9) is emptied αF water priαr tα thε welding operation. 5. A method according tα the claims 1 ... 3, c h a r a c ¬ t e r i z e d in that beFαre the protecting cover C9) is pressed tightly against the element Cl) tα be weldεd Fast, thε welding electrode C4) is disposed in the protecting cover C9) and the interior CIO) αF said protecting cαver is Fillεd with a suitable medium, preFerably pαlyurεtaπe αr wεlding Flux. 6. A method according tα the claim 1 or 2, c h a r a c ¬ t e r i z e d in that the welding electrode C4) is disposed in advance mithin thε protecting cover C9), that protecting cover C9) is permanently Fixed tα the element Cl) tα welded Fast, and that the opening C5) provided in the element Cl) Far the ωεlding electrode C4) is closed or covered with a remnant αr a suitable material, e.g. pro¬ tecting resin. 7. A method according tα the claims 1 ... 6, c h a r a c ¬ t e r i z e d in that gases Formed during the melding operation are evacuated frαm the interior CIO) αF the protecting cover C9) . 8. An apparatus Far accomplishing an underwater weld Jαint between a support C3) and an αntα a surFace C2) αF the support C3) brought element Cl) tα be ωeldεd Fast mith a ωelding electrαde C4), c h a r a c t r i z e d in cαmpri- sing; at least αne protecting cαver C9) disposed in tight relationship αntα the Free surFace of the element Cl) to be welded Fast, For insulating the Junction tα be ωelded betweεπ the support C3) and the element Cl) tα be ωelded Fast Frαm the ambient mass αF water, at least Far the duration αF the ωelding operation; at least one ωelding electrαde C4) , ωhich rotates about its longitudinal axis and extends through the ωall Cll) αF the cαver C9) in sealed relationship tα the ωall Cll) αF the cαver C9); and preFerably drive means For conducting ωelding current tα the ωelding electrode C4) and For rotating and leading the ωelding electrode C4) against the edges oF the opening C5) in the element Cl) during ths ωelding operation. 9. An apparatus according tα claim 8, c FTaT ' r a c t "ε-r i- z ε d in that thε hεad εdgε C12) αF the protecting cαver C9) disposed against the elεmεnt Cl) to bε ωεldεd Fast is Furnishεd ωith a gasket C13). 10. An apparatus according tα claim 8, c h a r a c t e ¬ r i z e d in that the protecting cαver C9) has beεn permanently Fastened to the element Cl) to be ωelded Fast. 11. An apparatus according tα any αne αF the precεding claims 8...10, c h a r a c t e r i z e d in that the interior CIO) αF the protecting cover C9) is connected tα a subatmospheric source through an αutflαω member 14) in the ωall Cll) αF the protecting cαver C9) . 12. An apparatus according tα any αne αF the preceding claims 8...11, c h a r a c t e r i z e d in that thε ωall αF the protecting cαver C9) is provided ωith an outFlαω member CIS), preFerably a pressure valve, opening at a predetermined pressurε . 13. An apparatus according tα any αne αF the preceding claims 8...12, c h a r a c t e r i z e d in that thε interior CIO) αF the protecting cαver C9) is Filled ωith a suitable Filler material, preFerably ωith pαlyuretane foam αr a ωelding Flux. 14. An apparatus according tα any αne αF the prεcεding claims 8...13, c h a r a c t e r i z e d in that at least a part αF the ωεlding εlεctrαdε C4) ωithin the interior CIO) αF thε protecting cαver C9) has conically Formed tα taper tαωards the support C3) . 15. An apparatus according tα any αne αF the preceding claims 8...14, c h a r a c t e r i z e d in that thε matεrial thickness αF the melding mass C17) in the melding electrode C4) is constant. 16. An apparatus according tα any αne oF the preceding claims 8...15, c h a r a c t e r i z e d in that the drive means C23) comprises gripping means C24) grasping that part αF the ωelding elεctrαdε C-4-) - ωhich protrudes Frαm the protecting cover C9) as ωell as rotating mεans C25) rotating thε ωεlding electrαde C4) during the ωelding operation and pushing said electrαde against the edgεs αF the opening C5) in the elεmεπt C4) tα be ωelded Fast at a speed substantially corresponding tα the cαnsumptiαn αF the ωelding electrαde C4) . 17. An apparatus according tα claim IB, c h a r a c t e ¬ r i z e d in that the gripping means C24) consists αF hydraulically movable Jaωs C2B,27). 18. An apparatus according tα claim IB, c h a r a c t e ¬ i z e d in that the rotating means C25) is a hydraulic motor Furnished ωith a screeω Feeder C28) For the ωelding electrαde C4) and ωith current-conducting carbons C29) For conducting the ωelding current to said ωelding electrode. 19. An apparatus according to any one αF the preceding claims, c h a r a c t e r i z e d in that a guide bushing C30) For the ωelding electrαde C4) has been provided in the protecting cover C9), said bushing having a gasket For the sealed inlet αF the ωelding electrαde C4) . 20. An element to be ωelded Fast ωith the method αF claim 1 and ωith the apparatus oF claim 8 For accomplishing an underωatεr ωεld joint, c h a r a c t ε r i z ε d in having at lεast αnε conically in dirεctiαn tαωards to thε support C3) tapering opening C5) For the ωelding elεctrodε C4) ωhich rotates about its longitudinal axis. 21. An element according tα claim 20, c h a r a c t e r i¬ z e d in that the prαFile oF the opening C5) corresponds substantially tα that αF the ωelding electrαde C4) tα be pushed thεrein. 22. An element according tα claim 20 αr 21, c h a r a c t¬ e r i z e d on that the a spacer ring C6) oF an elastic material, preFerably rubber, is Fastenεd tα thε element Cl) tα be ωelded Fast, to the surFace thereoF disposed against the support C3), said spacer ring being disposed cαaxially ωith the opening C5) For the ωelding elεctrαde C4) 23. An element according tα any αne oF the preceding claims 20...22, c h a r a c t e r i z e d in that said element is permanently Fastenεd in advancε tα the protec¬ ting cover C9) and that the opening CS) in said element provided Far the ωelding electrodε C4) is closed ωith a material remnant αr ωith a suitable material, e.g. protec¬ ting resin. STATEMENTUNDERARTICLE19 Tα clarify the amendments is important First tα inform something about discoveries during the tests of the appa¬ ratus according tα the invention. By leaving a thin material remnant αf the element Cl) in the bottom αf the boring Far the opening C5) instead for applying protection resin can be reached bath good sealing against the permeate of mater into the protecting cαver C9) and good welding results because Just the arc αF the electrode penetrades this thin material remnant whereby the electrαde Cl) as ωell as the Junction tα be ωelded are insulated Frαm the ambient mass αf water and the welding can certainly be made as a dry-welding method. Because αf this discovery it is not essential Far the element Cl) ta be welded Fast that the baring af the opening C5) extends through the element Cl). In view aF the citations mentioned in the search rεpαrt as well as the discovery mentioned above the Fallowing amendments have been made in the claims. Claims not mentioned underneath are similiar tα the resp. original claims. CLAIM 1: Expressions "pressed" and "extending through" in the lines 13 to 14 have been amended resp. tα Farm "led^_ and "in". CLAiπ 6: Definition "... is covered with a sui¬ table ..." in the lines 13 tα 14 is amended to farm " ...is_ closed , or cave- red mith . a . remnant αr_ a suitable ... " . CLAIM 8: Expression "pressing" in the line 35 is amended tα orm "leading". CLAIM 20: Expression "mith a welding electrαde CD" in line 30, and expression "exten¬ ding through it" in line 33 have been cancelled. CLAIM 23: Definition "... is covered ωith a sui¬ table ..." in lines 15 tα 16 is amended tα arm "... is_ closed with_ a material remnant αr with a suitable...".

Inventors: MAEKELAEINEN HANNU, NIINIVAARA JUHANI, MAEKELAEINEN, HANNU, NIINIVAARA, JUHANI
Applicants: GSS GENERAL SEA SAFETY LTD OY, MAEKELAEINEN HANNU, NIINIVAARA JUHANI, MAEKELAEINEN, HANNU, NIINIVAARA, JUHANI, OY GSS GENERAL SEA SAFETY LTD
Application year: 1985
Main classification: B23K9
IPC codes: B23K9, C23F13