FI83601C - Automatically in an underwater construction of metal by welding removable device and method for automatically providing one underwater weld joint - Google Patents

Description

83601

DEVICE FOR AUTOMATICALLY ATTACHING A UNDERWATER METAL STRUCTURE BY WELDING AND A METHOD FOR AUTOMATICALLY PERFORMING AN UNDERWATER WELDING JOINT

The present invention relates to a method for performing underwater welding, in which the pieces to be welded together are placed opposite each other at the joint and one of the pieces is provided with a protective cover covering the joint, within which the pieces are welded to each other with a movable electrode.

Hitherto known and used methods for performing demanding underwater welding tasks (e.g. attachment of anodes used to prevent corrosion) involve complex and expensive equipment and the welding is performed hyperbarically. So-called wet welding in anode mounting is out of the question because the requirements of classification societies such as Det Norske Veritas cannot be met. In wet welding, the problem is the hardening of the base material and the formation of hydrogen cracks.

Underwater welding work has grown strongly in recent years in the so-called due to the proliferation of offshore installations and, in particular, the increase in offshore oil drilling. The worst problem with such offshore plants is corrosion corrosion, which, if left untreated, destroys the plant unusable in a short time. Attempts have been made to solve this problem by attaching anti-corrosion anodes to underwater parts. The same method is also used to prevent corrosion of ships and bridges. One of the most important tasks in the maintenance of these plants is the replacement of corroded anodes with new ones. Underwater welding work is very difficult and expensive.

The so-called so-called underwater repair work is already known. Habitat chamber welding method, which has also been used to attach anti-corrosion anodes. This known method is based on the fact that the object to be repaired or the object to which the body to be attached (e.g. the anti-corrosion anode) is attached is surrounded by a special chamber in which the diver performs the necessary welding operations. Such a Habitat chamber welding method aims to meet the quality requirements set by different classification plants by welding, but the method is very expensive in terms of operating and investment costs and also requires the presence of a skilled diver. The method is also not suitable for robot welding.

The use of a robot to perform underwater welding tasks (e.g. attaching anodes) is advantageous, especially for reasons of occupational safety and efficiency. However, with the welding methods used so far, e.g. attachment of the anode by means of a robot, it has been almost impossible.

An advantage of the present invention over previous methods is to achieve a very high quality welding result without a hyperbaric chamber and a separate device or tool. The invention is characterized in that a groove is formed at the seam point by thinning a groove around which the protective housing is sealed so that welding takes place in a watertight chamber delimited by said body and the housing.

Based on the developed method, the part attached to the welding joint (eg the anode leg) is welded automatically. The underwater welding connection according to the method is created automatically so that the robot or diver takes the weldable part (e.g. an anode with legs according to the invention) to the installation site (on a pre-cleaned weldable substrate), after which the welding device can be commanded by remote control. hit-sausvirta. The welding current cable can be connected to the part to be welded already above the water surface or the diver connects it to a special welding current connector according to the invention. The connection of the cable to the welding current 1ii11 can take place, for example, by means of a permanent magnet. When attaching e.g.

3 83601 anodes by means of a robot The robot gripping member may have current terminals corresponding to the welding current terminals of the anode, which press against the anode current terminals, eg hydraulically or by spring force. The required welding current can also be taken from a battery attached to the anode.

The invention also relates to a construction for applying the method, comprising a body for welding underwater attached to another body, a protective housing covering said welding point connected to said body, and a movable electrode inserted inside the protective housing, by means of which a weld seam can be formed. a groove is formed at the welding point by thinning the wall of the body, along which the seam can be formed, and that the protective housing is sealed around the groove so as to define, together with the body to be welded, a watertight chamber inside which welding takes place.

In the following, the invention will be described in more detail by way of example with reference to the accompanying drawings, in which

Figure 1 shows a partial view of a method / construction according to the invention: Figure 2 shows a detail of a method / construction according to the invention:

Figure 3 shows a method / construction according to the invention in partial section during welding

Figure 4 shows a single embodiment of a construction according to the invention. . ty i skohtaa.

·. The body to be welded, eg the anode foot (Figure 1) in this method, consists of the following parts: .1. * - Anode foot body part 1 containing a thinned point "(a) with a material thickness of about 1-2 mm. Thinned point ( Fig. 2) 4 83601 can be made, for example, by milling a notch on the side to be welded to the anode foot with a profile blade, which does not completely penetrate the foot material.During the welding operation, the body part 1 is connected to the earth conductor of the welding current source.

- The protective housing 2, which together with the leg body part 1 forms a completely watertight protective chamber (b). Welding electrode 3 located above the groove in the body at a distance of about 3-5 mm from the bottom of the groove (Figure 2). The electrode 3 has a small auxiliary electrode located at the tip, which ensures the ignition of the welding arc. A flexible conductor is also connected to the electrode, which galvanically connects it to the connector 7 of the welding current 1.

- A mass 4 filling the chamber (b), containing powder and an adhesive oxygen-containing substance. This mass holds the electrode firmly in place and when burned releases oxygen and releases the electrode to the target to be welded. The glowing mass prevents the welded part from cooling too quickly after the electrode has been welded, which is of great importance for achieving a high-quality welding result.

- A spring 5 extending from the end of the welding electrode to the current 1ii11, which, due to its bias, turns the welding electrode 3 into the groove to be welded when the electrode burns. The spring 5 can be, for example, a coil spring made of round wire, which surrounds the flexible current conductor of the welding electrode 3.

: '- An electrode against the welding point (based on the protective housing 2) - a heavy support 6 which, due to the thermal expansion caused by the combustion heat of the filling mass 4, slowly moves the electrode to the object to be welded, igniting the welding arc. Support 6 can be so-called. based on the bimeta11 structure. The structure according to the invention allows 100% ignition of the welding electrode.

- A welding current connector 7 which generates a welding current in the through-flow chamber (b). The design of the welding current 1ii11ime 7 corresponds to \. the design of the power cable or installation robot: · the equivalent of the welding current supply. The welding current connector 7 is galvanically connected to the current conductor of the welding electrode ... and sealed and galvanically isolated from a protective housing 2 to which it is mechanically attached.

5 83601 - An annular sealing and insulating part 8, which forms a watertight seal and at the same time galvanic insulation between the welding current connector 7 and its protective housing 2. The seal 8 (insulator) may be, for example, rubber or a rubber-like substance, a curable mass or a hard insulating material (e.g. "Teflon").

- An outflow member 9, which can be connected to a vacuum source. The outflow member 9 can also be a pressure valve that opens at a predetermined pressure, through which water vapor formed from possible moisture and the generated welding gases escape from the chamber (b) during the welding operation.

- Ignition device 10 for the filling mass 4, which operates e.g. with the current taken from the welding current 1 connector 7 and can be attached e.g. to the part to be welded (e.g. the body part of the anode leg) or to the protective housing 2.

- An annular, resilient part 11 or a mass or curable mass sealing to the weldable part of the protective housing 2 or to the body part 1 of the anode leg.

- An annular sealing part 12 of elastic material surrounding the welding point, which adheres to the welded surface of the body of the welded part or anode, which is pressed between the part to be welded and the mating surface of the base (c in Fig. 1). The part may be partially embedded in the body part 1.

- A paste-like mass applied to the welded surface of the part to be welded, inside the annular sealing part 12: a mass 13 which displaces water from the welding point when the part to be welded is pressed against the mating surface of the underwater base. The paste 13 has been developed in such a way that it does not weaken the hit joint or the base material. During welding, the paste 13 burns from an area of about 5-10 mm around the point to be welded (Fig. 3).

The thin base of the groove (a in Fig. 1) in the body part of the part to be welded according to the method acts as a sealing compound 13. as a substrate and prevents water from penetrating even in high pressure into the welding chamber (b) when installing the part to be welded. When the welding electrode burns, the bottom material of the groove melts and together with the material of the molten substrate (c) forms a welding seam.

6 83601

The sealing paste 13 burns from an area of about 5 mm around the weld seam and the rest of the paste forms a sealing surrounding protective ring and thus prevents water from entering between the base to be welded and the body to be welded (e.g. the anode leg). The sealant contains the following compounds and elements in said ratio: water H 2 O 50.6% proteins 13.2% fats 30.4% sodium Na 1.01% potassium K 0.108% magnesium Mg 0.048% calcium Ca 0.355% iron Fe 0 .0014% phosphorus P 0.795%

The welding chamber (b) contains at least one welding electrode which protrudes or turns at the welding point at a speed corresponding to its welding speed. The welding electrode can rotate about its longitudinal axis, the force moving the electrode can be generated by means of a slow explosive (Fig. 4). The outflow member 9 can be a pressure equalizer provided with a gas piston or a bellows.

It will be clear to a person skilled in the art that the various embodiments of the invention are not limited to the example given above but may vary within the scope of the appended claims.

Claims (10)

A method for performing underwater welding, in which the pieces (1, c) to be welded together are placed opposite each other at the joint and one of the pieces (1) is provided with a protective cover (2) covering the joint, within which the pieces are welded together with a movable electrode (3). forming the body (1) to be welded by thinning the groove (a) around which the protective housing (2) is sealed so that welding takes place in a watertight chamber (b) delimited by said body and the housing. Method according to Claim 1, characterized in that a combustible sealing paste (13) is applied between the bodies (1, c) to be welded, which prevents water from entering the joint. Method according to Claim 1 or 2, characterized in that the chamber (b) in which the welding takes place is filled with a combustible mass (4), such as a mixture of gunpowder and an adhesive. Method according to one of the preceding claims, characterized in that the electrode (3), the current conductor of which is inserted into the chamber (b) via a watertight connector (7), is moved in the chamber during welding so as to follow the groove (a) along the weld seam. is formed. Method according to Claim 4, characterized in that the electrode (3) is rotated in the chamber (b) by means of a spring (5) connected to it. Method according to Claims 3 and 4, characterized in that the electrode (3) is rotated in the chamber (b) by pushing it by means of a member (6) which moves under the effect of the thermal expansion caused by the combustion of the mass 8 (8) in the chamber. A construction for applying a method according to any one of the preceding claims, comprising a body (1) for welding underwater to a second body (c), a protective housing (2) covering the welding site connected to said body (1), and a protective housing a movable electrode (3) with which a weld seam can be formed, characterized in that the wall of the body (1) is formed at the weld point by thinning the groove (a) along which the seam can be formed, and that the shield housing (2) is sealed around the groove so that it, together with the part to be welded, defines a watertight chamber (b) inside which the welding takes place. 7 83601 Construction according to Claim 7, characterized in that the chamber (b) in which the welding takes place is filled with a combustible mass (4), such as a mixture of gunpowder and an adhesive. Construction according to Claim 7 or 8, characterized in that the current conductor of the electrode (3) is inserted into the chamber (b) via a watertight connector (7) and in that the electrode is arranged to move in the chamber so as to follow the groove (a). a weld seam is formed. A construction according to claim 9, characterized in that the electrode (3) is arranged to pivot by engaging a spring (5) and / or a movable member (6) under the effect of thermal expansion caused by the combustion of the mass (4) in the chamber (b). 9 83601