Background : More than one hundred years of the arc and are used worldwide . But first underwater welding was done by the British Navy - at that time a shipyard in order to seal the leaking ship rivets below the water had been used of underwater welding . In productive work that is done under water , underwater welding is considered a key tool . In 1946 , a special waterproof electrodes was developed in the Netherlands by Van Vylyjn 1 . Cross- shore structures such as offshore drilling oil wells , pipelines and platforms are constructed in particular water , have increased dramatically in recent years . Some of its elements or structural defects in disasters such as hurricanes will experience . Among these structures require any repair method used in underwater welding .
Classification ×
Underwater welding can be classified in two categories :
1 . Wet Welding
Two . Dry welding
The method of wet welding , underwater welding operations have been implemented and are dealing directly with a wet environment . In dry welding method , a dry chamber welding should be created in the local vicinity and welding work is performed by placing the chamber .
× wet welding :
Name indicates that wet welding underwater welding is done , is directly exposed to the humid environment . In this method, a special electrode is used for welding and welding , manual welding in outer space, just as water is done , is done. Autonomy as a welder during welding , this method is more effective and wet welding method is efficient and economical point of view . Nyrvyjvshkary is based on the supply cables and hoses are connected to the diver and welder .
In wet welding MMA ( manual metal arc welding ) 2 on two properties are used :
Power supply : dc
Polarity : negative polarity
If the terminals + DC and used over and cause Brqkaft Khrabshdgy and rapid loss of electrode holders are metal components . For wet welding AC current due to the lack of adequate security and protection problems in the submerged arc exists, can not be used .
Should supply a direct current machine with ampere ratings of 300 or 400 is. Motor generator welding machines are often used for wet welding . The welding machine frame should be at the bottom , is placed under the ship . Welding circuit should include a good switch blade is usually a key is used for steering the welder divers . Key blade in the circuit during welding electrode should be resistant against breaking and is secure . During the welding process welding power source should only be connected to the electrode holder . The method of direct current with electrode negative and electrode holders with special insulation against the water are used.
Type electrode is used as the standard AWS ( American Welding Society ) classification E6013 is 3 .come in contact metal conductor , the defect and the arc is not working . In addition, the rapid corrosion of the copper part of the insulators may be cracked , can occur .
Hyperbaric welding × 4 (dry welding)
Hyperbaric welding chamber sealed around the structure or weld a piece that will be used. The ambient pressure chamber filled with a gas ( usually helium containing oxygen is 5 ½ times ). This position is located on the pipeline and have breathable air and oxygen mixture Hlyv and pressure -filled or pressure welding is done far more than it runs . In this method, high-quality welding joints can be created so that the X-ray and other equipment may be necessary . Gas tungsten arc welding process in this section shall be applied . The following area is a place exposed to water . The welding was done in the land , but the hydrostatic pressure of the sea water is surrounding environment .
× risks involved
Electric doubt there will be danger for divers or welder . Precautions that have been taken include suitable and sufficient Yq welding equipment , depending on the electricity supply to the ends of the arc voltage limit metal arc welding of open-circuit equipment , welding , hand . Another danger of producing hydrogen and oxygen by the arc in wet welding .
Precautionary measures should be adhered to in the handling of gas cylinders . Because they potentially have the ability to explode . A further danger that threatens the life or health of welders exposed to air and nitrogen at high pressure and can injure him .
The structures of their underwater wet welding , inspection of welding and after welding may be more difficult than that of the outside air is done. To ensure the integrity of such underwater welds find a more important and the probability that an unknown fault and shortcoming appears there.
× advantages of dry welding
1 . Diver Safety - Welding was performed in a chamber which causes or is likely to remain safe welding of ocean currents and sea creatures are . The warm , dry place and has good lighting control system also uses special environment (ESC) 6.
Two . Good quality welds - Welding capability of this method is that it can even bring about a union of open space in comparison to air . The reason is that there are no longer any hot water or cut off . And the amount of hydrogen (H2) production is much lower than wet welding .
Three . Level control - joint preparation , alignment tube of anti- Destructive Testing (NDT) (7) , etc. The objective is to control and regulate .
4 . Non- destructive testing (NDT) - a non-destructive test positions for dry environments is facilitated .
× dry welding defects
1 . Welding chamber or place of complex and high support needs and knows how unconventional chamber complex.
Two . Cost and financial value to the chamber considerably high and the cost increases with depth . Welding depth at the impact , so that the greater depths of the arc voltage and the Bolter and accordingly is essential . Do a welding job like this cost is estimated at $ 80,000 . And sometimes can not be used as a chamber for different work , but the problem depends on the type of work and the differences between them.
× advantages of wet welding
The underwater wet welding is done by hand , the restoration and refurbishment of offshore structures is growing rapidly in recent years .
Among the benefits of wet welding can include :
1 . Wet welding versatility and low cost makes it highly desirable to be this way .
Two . Enjoying the operation speed is another advantage of this method .
Three . Compared to dry welding is less expensive.
4 .
5 . Not require any type of enclosure is lost for so long . Standard Equipment Readily available for use. A means for performing a welding operation is not needed .
× wet welding defects
Although wet welding has been widely used , but still suffers from flaws , such as those listed below :
1 . Quick temper discoloration weld metal - the temper discoloration of the water around it. However, taking the tension force in the welding temper discoloration increases the effectiveness of the insecticide susceptibility and reduced the weld , which significantly increases the hardness and Rosen .
Two . Hydrogen production - Large amount of hydrogen in the weld region is separated by water vapor in the arc is created . H2 at medium heat affected (HAZ) (8) in which the weld metal is dissolved microscopic cracks and gaps are created .
Three . Another disadvantage of the visual ability is low . Sometimes we can not welding to weld the right area
× wet welding performance
Underwater wet welding process is done through the following steps :
Piece of work that is being welded electrical circuit connected to one side and a metal electrode on the other side of the circuit. The two parts of the circuit ( the electrode and the workpiece ) are close to each other , but after a little while they are separated . While approaching the electrode to the workpiece , the current gap and cause an electrical spark is Conservative ( ARC ) and melt the metal and form the weld area is . At this time, the tip electrode and molten metal droplets into the weld pool is . During this operation the molten tip of the electrode covering the electrode and a shielding gas are created. Which was said to strengthen the flow of the arc and the molten metal will be protected . Like a hole in the weld arc melts and reveals .
× progress in the field of underwater welding.
Long wet welding is a welding technique , used underwater and is still conventional bin . With recent advances in the field of offshore structures has been learned , how important prediction of underwater welding has increased . This finding led to the development of other methods such as welding, welding, abrasive , 9 , 10 , and explosive welding, vertical welding material 11 is already sufficient to provide acceptable and there.
× range of future developments
tendency is toward automation . THOR-1 12 or more push -oriented robot control which uses tungsten inert gas , to promote the installation of piping and pipeline operations where divers will do the rest of work processes be responsible
Classification ×
Underwater welding can be classified in two categories :
1 . Wet Welding
Two . Dry welding
The method of wet welding , underwater welding operations have been implemented and are dealing directly with a wet environment . In dry welding method , a dry chamber welding should be created in the local vicinity and welding work is performed by placing the chamber .
× wet welding :
Name indicates that wet welding underwater welding is done , is directly exposed to the humid environment . In this method, a special electrode is used for welding and welding , manual welding in outer space, just as water is done , is done. Autonomy as a welder during welding , this method is more effective and wet welding method is efficient and economical point of view . Nyrvyjvshkary is based on the supply cables and hoses are connected to the diver and welder .
In wet welding MMA ( manual metal arc welding ) 2 on two properties are used :
Power supply : dc
Polarity : negative polarity
If the terminals + DC and used over and cause Brqkaft Khrabshdgy and rapid loss of electrode holders are metal components . For wet welding AC current due to the lack of adequate security and protection problems in the submerged arc exists, can not be used .
Should supply a direct current machine with ampere ratings of 300 or 400 is. Motor generator welding machines are often used for wet welding . The welding machine frame should be at the bottom , is placed under the ship . Welding circuit should include a good switch blade is usually a key is used for steering the welder divers . Key blade in the circuit during welding electrode should be resistant against breaking and is secure . During the welding process welding power source should only be connected to the electrode holder . The method of direct current with electrode negative and electrode holders with special insulation against the water are used.
Type electrode is used as the standard AWS ( American Welding Society ) classification E6013 is 3 .come in contact metal conductor , the defect and the arc is not working . In addition, the rapid corrosion of the copper part of the insulators may be cracked , can occur .
Hyperbaric welding × 4 (dry welding)
Hyperbaric welding chamber sealed around the structure or weld a piece that will be used. The ambient pressure chamber filled with a gas ( usually helium containing oxygen is 5 ½ times ). This position is located on the pipeline and have breathable air and oxygen mixture Hlyv and pressure -filled or pressure welding is done far more than it runs . In this method, high-quality welding joints can be created so that the X-ray and other equipment may be necessary . Gas tungsten arc welding process in this section shall be applied . The following area is a place exposed to water . The welding was done in the land , but the hydrostatic pressure of the sea water is surrounding environment .
× risks involved
Electric doubt there will be danger for divers or welder . Precautions that have been taken include suitable and sufficient Yq welding equipment , depending on the electricity supply to the ends of the arc voltage limit metal arc welding of open-circuit equipment , welding , hand . Another danger of producing hydrogen and oxygen by the arc in wet welding .
Precautionary measures should be adhered to in the handling of gas cylinders . Because they potentially have the ability to explode . A further danger that threatens the life or health of welders exposed to air and nitrogen at high pressure and can injure him .
The structures of their underwater wet welding , inspection of welding and after welding may be more difficult than that of the outside air is done. To ensure the integrity of such underwater welds find a more important and the probability that an unknown fault and shortcoming appears there.
× advantages of dry welding
1 . Diver Safety - Welding was performed in a chamber which causes or is likely to remain safe welding of ocean currents and sea creatures are . The warm , dry place and has good lighting control system also uses special environment (ESC) 6.
Two . Good quality welds - Welding capability of this method is that it can even bring about a union of open space in comparison to air . The reason is that there are no longer any hot water or cut off . And the amount of hydrogen (H2) production is much lower than wet welding .
Three . Level control - joint preparation , alignment tube of anti- Destructive Testing (NDT) (7) , etc. The objective is to control and regulate .
4 . Non- destructive testing (NDT) - a non-destructive test positions for dry environments is facilitated .
× dry welding defects
1 . Welding chamber or place of complex and high support needs and knows how unconventional chamber complex.
Two . Cost and financial value to the chamber considerably high and the cost increases with depth . Welding depth at the impact , so that the greater depths of the arc voltage and the Bolter and accordingly is essential . Do a welding job like this cost is estimated at $ 80,000 . And sometimes can not be used as a chamber for different work , but the problem depends on the type of work and the differences between them.
× advantages of wet welding
The underwater wet welding is done by hand , the restoration and refurbishment of offshore structures is growing rapidly in recent years .
Among the benefits of wet welding can include :
1 . Wet welding versatility and low cost makes it highly desirable to be this way .
Two . Enjoying the operation speed is another advantage of this method .
Three . Compared to dry welding is less expensive.
4 .
5 . Not require any type of enclosure is lost for so long . Standard Equipment Readily available for use. A means for performing a welding operation is not needed .
× wet welding defects
Although wet welding has been widely used , but still suffers from flaws , such as those listed below :
1 . Quick temper discoloration weld metal - the temper discoloration of the water around it. However, taking the tension force in the welding temper discoloration increases the effectiveness of the insecticide susceptibility and reduced the weld , which significantly increases the hardness and Rosen .
Two . Hydrogen production - Large amount of hydrogen in the weld region is separated by water vapor in the arc is created . H2 at medium heat affected (HAZ) (8) in which the weld metal is dissolved microscopic cracks and gaps are created .
Three . Another disadvantage of the visual ability is low . Sometimes we can not welding to weld the right area
× wet welding performance
Underwater wet welding process is done through the following steps :
Piece of work that is being welded electrical circuit connected to one side and a metal electrode on the other side of the circuit. The two parts of the circuit ( the electrode and the workpiece ) are close to each other , but after a little while they are separated . While approaching the electrode to the workpiece , the current gap and cause an electrical spark is Conservative ( ARC ) and melt the metal and form the weld area is . At this time, the tip electrode and molten metal droplets into the weld pool is . During this operation the molten tip of the electrode covering the electrode and a shielding gas are created. Which was said to strengthen the flow of the arc and the molten metal will be protected . Like a hole in the weld arc melts and reveals .
× progress in the field of underwater welding.
Long wet welding is a welding technique , used underwater and is still conventional bin . With recent advances in the field of offshore structures has been learned , how important prediction of underwater welding has increased . This finding led to the development of other methods such as welding, welding, abrasive , 9 , 10 , and explosive welding, vertical welding material 11 is already sufficient to provide acceptable and there.
× range of future developments
tendency is toward automation . THOR-1 12 or more push -oriented robot control which uses tungsten inert gas , to promote the installation of piping and pipeline operations where divers will do the rest of work processes be responsible
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