Electroslag Welding Process

Also known as ESW, electroslag welding is a method where a primary arc is used at first to heat the slag and is then smothered by the conductive slag. The heat is then generated by the slag resisting the electricity passing between the consumed electrode and the work. It is usually used to weld steel in a vertical position and was used widely in the Soviet Union in the 1940's. This is not an arc welding process however, though an arc is briefly ignited in the beginning stages. Past this, there is not arc involved in the procedure. The thickness limit for this welding process reaches up to 30". Extreme heat helps to gain this type of penetration, and multiple electrodes can be used to speed up this process. In the 1970's, electroslag welding became a popular choice for welding metals that were very thick. These applications include parts for bridges, buildings, ships, and pressure vessels.

The positive side of electroslag welding is that very thick metals can be joined and multiple electrodes can be used to complete a weld in a single pass. The heat is held in the weld longer and gas bubbles are allowed to escape from the weld pool before it cools. The entire process is automatic and once it starts it does not stop until the weld is complete. For large or thick pieces of stock, electroslag welding is the quickest way to join the pieces together. There is very little work that needs to be done to prepare the joints prior to welding and the distortion of the metal is relatively low. The drawbacks come from the fact that the system is very complicated and only works on flat or vertical joints. Also some of the instruments used in this procedure have to be cooled with a constant water supply.

Stud Welding Process

Stud welding is defined as a method of arc welding in which "permits rapid attachment of studs and other fasteners to a structure without piercing the structure metal". There is no filler metal, and shielding gas, flux, or ceramic shield around the stud are all optional. Once the metals on the stud and the base piece are heated enough to be joined, they are pressed together in order to fuse them mutually. The stud is sometimes encased on the end with a ceramic cuff in order to defend the arc and the welding surfaces from the surrounding environment. For some while, this form of arc welding is not a true disparity of it. Stud welding uses principles from arc welding and from forge welding. An arc is used to heat the metal, but then a power is used to adhere the pieces together.

In contrast to drilling and tapping, stud welding in superior. The base metal is not weakened and a water tight seal is not destroyed, as is the case with drilling and tapping. Also, costs and time are minimized when compared to the other two. Robots are now being used to place and set the studs, which also decreases time. Every location can be welded from, but vertical and overhead positions are not easily finished. A variety of metals can be used as well, not just ferrous metals.

Body Protection While Welding

Welders should also wear clothing that will protect them against bums from hot sparks or metal. Very hot work calls for protective leather aprons, leggings, and sleeves. Street clothes are acceptable for some welding jobs, if you follow these precautions:

• Wear long-sleeved shirts. Arc welders should wear clothing made of heavy material to protect against ultraviolet rays.


• Keep collars and cuffs buttoned.


• Do not wear clothes with cuffs or open pockets that could catch sparks.


• Wear high shoes, and keep pant legs over them to keep sparks out.


• Wear flame-resistant head covers.


• Wear clean clothes-grease or oil spots could be flammable.


• Do not wear flammable hair preparations.


• Never carry flammable items, such as cigarette lighters, on your person when involved in any welding process.
  
  
• For arc welders, special dry welder’s gloves are a must to protect against shock to the hands or electrocution.

Some welding jobs also call for wearing respirators to protect against inhaling fumes and gases. There are special welding respirators available. Follow the instructions of the welding equipment manufacturers, material safety data sheets (MSDSs) for any gas or materials used in a welding operation, and your safety department in choosing the correct respirator. As with any respirator, it should be properly fit-tested for the individual wearer, and each employee must be trained in its use.

Welding and Cutting Quiz

1. Voltages less than 50 volts: a) can cause fatal shock under all condition, b) cannot cause fatal shock under any conditions, c) can cause fatal shock under some conditions.
   
   
2. Arc welding machines are typically greater than 50 volts. T__, F__
   
   
3. A person who has wet hands or feet is more susceptible to electrocution than a person who is dry. T__, F__
   
   
4. Because metal frames in processing plants are intentionally well-grounded, a person in contact with such a frame while using an arc welder or other electrically-powered tools is much more susceptible to electrocution than one who is not. T__, F__
   
   
5. Hazards of arc welding include: a) Electrocution, b) Fires, c) Flesh burns to eyes from UV radiation, d) Burns from sparks, e) Metal fumes, f) Heat-related explosives g) Production of toxic gases when used near cleaning operations using chlorinated hydrocarbons.
   
   
6. Hazards of oxy fuel welding include: a) Fires, b) Explosion of oxygen, c) Explosion of acetylene, d) Fire and explosions when gases mix in lines, e) Metal fumes, f) Flash burns to eyes, g) Heat-related explosions.
   
   
7. An acetylene cylinder should: a) be transported on its side with the cap on, b) be transported upright with the cap on, c) be stored upright for a few hours prior to using if accidentally laid on its side.
   
   
8. Using oxygen to blow off clothing: a) is a fire hazard, b) results in an oxygen-enriched atmosphere in the clothing for some time after.
9. An oxy-acetylene torch: a) cuts steel, b) burns steel
   
   
10. Using oil or grease on an oxygen regulator: a) is likely to cause the grease to burn, b) is likely to cause the regulator to burn, c) is likely to cause the cylinder to explode and go airborne.
    
    
11. The valve on an oxygen cylinder must be opened: a) ¼ turn, b) ½ turn, c) ¾ turn, d) all the way.
    
    
12. The valve on an acetylene cylinder must be opened: a) ¼ turn, b) ½ turn, c) ¾ turn, d) all the way, e) never more than what allows the gage pressure to reach 15 psig.
    
    
13. Acetylene gas is extremely unstable when compressed. T__, F__.
    
    
14. Acetylene cylinders: a) are filled with a porous substance, such as calcium silicate to eliminate pockets of gaseous acetylene of appreciable size, b) have the acetylene dissolved in acetone.
    
    
15. Acetone can hold 400 times its own volume of acetylene at a working pressure up to 250 psig. T__, F__.
    
    
16. Oxygen and acetylene cylinders must: a) Have the cap when not in use, b) Be secured in the upright position both during storage and use, c) Be protected from being bumped when the regulator is on, d) Be stored at least 20 feet apart or separated by a noncombustible barrier at least five feet high with a fire-resistance rating of at least 1/2 hour.
    
    
17. Allowing the pressure in either cylinder in an oxyacetylene welding system to decrease below 20 psig: a) Is unsafe, b) May result in backflow of the gas from the other cylinder creating an explosive mixture.
    
    
18. Allowing the sun to heat a cylinder to 500 degrees F, could a) increase the pressure by over 10%, b) increase the pressure by over 50 %, c) increase the pressure by over 100 %.
    
    
19. Taking oxy-acetylene welding cylinders into a confined space: a) is unsafe, b) could result in leakage of the gas causing a fire and explosion hazard,
    
    
20. Oxygen is: a) explosive b) makes everything in an oxygen-enriched atmosphere more flammable.
    
    
21. Regulators are required on oxygen and fuel gas cylinders. T__, F__
    
    
22. Before a regulator is attached to a cylinder valve: a) the valve should be “cracked” wide open, b) the valve should be opened slightly and immediately closed.
    
    
23. Fuel gas hoses are colored red. T__, F__
    
    
24. Oxygen hoses are colored green. T__, F__
    
    
25. Chemically inactive gas hoses are black. T__, F__
    
    
26. Hose clamps are suitable for splicing hoses used in oxy-acetylene welding applications. T___, F__
    
    
27. Matches and butane lighters are suitable for lighting a cutting/welding torch. T__, F__
    
    
28. When a welder is changing electrodes, he or she should be on a a) conductive, b) nonconductive surface
    
    
29. Electrodes should be removed from holders when the welder is turned off. T__, F__.
    
    
30. Polyester clothing should a) never b) usually c) always be worn when welding
    
    
31. Polyester is: a) flame resistant, b)burns easily, c) melts on your skin increasing the severity of burns.
    
    
32. Welding or cutting areas must be: a) protected from water, b) protected from wind, c) Fire safe
    
    
33. You can recognize whether or not fumes from a welding rod are hazardous by: a) looking at the color of the smoke, b) smelling the smoke, c) looking at the Material Safety Data Sheet.
    
    
34. Grease and oil must be stored at least a) 5 feet, b) 10 feet, c) 20 feet, d) 40 feet, e) 50 feet from oxygen.
    
    
35. Empty fuel gas and oxygen cylinders can be stored together? T__, F__
    
    
36. Personal protective equipment for welding or cutting includes: a) eye and face protection, b)skin protection, c) respiratory protection, d) hearing protection.
    
    
37. Effective ventilation is a better alternative than respiratory protection in most cases. T__, F__.
    
    
38. When personnel leave the confined space, the oxy-acetylene torch and hoses must be removed from the space. T__, F__
    
    Answers: 1)c, 2)T, 3)T, 4)T, 5)abcdefg, 6)abcdefg, 7) bc, 8)ab, 9)b, 10)abc, 11)d, 12)e, 13)T, 14)ab, 15)T, 16)abcd, 17)ab, 18)c,19)ab, 20)ab, 21)T, 22)b, 23)T, 24)T, 25)T, 26)F, 27)F, 28)b, 29)T, 30)a, 31)bc, 32)abc, 33)c, 34)d, 35)F, 36)abcd, 37)T, 38)T

History of Welding

Welding has been around since the Ancient Egyptians In one form or another. Welding really became extremely useful in the early 19th century, and once the industrial revolution started it was used extensively. The history of the world has been drastically shaped from the process of welding. It has allowed people to fix things and build things that other wise would have not been possible. The early metal ships were all bolted together, which created many problems. The problems were that they were extremely time consuming, because each individual rivet or bolt had to be drilled and put in place. The other problem was that all the seams would leak and the had to be sealed with a type of sealant. Welding allowed the ships seams to be fused together allowing them to be built much faster, plus they were permanently sealed, and required a lot less maintenance.

Welded ships also were more durable, because welds were as strong or stronger then the metal itself. The Panama Canal also required a lot of welding and may have not been possible without welding. It has helped to create a lot of machines, and even bombs used in the world wars. So as you can see welding has help shape the history of the human race. And it continues to do so even still today by helping create all kinds of products.