Inert Gas Welding and Spot Welding Difference:

Unlike inert gas welding, spot welders do not require a shielding gas to eliminate weld contamination or filler metal to build up the weld.

A spot weld is a resistant weld that sits within the two pieces of metal. The finished weld is flush or slightly recessed to the exterior of the base metals and has a silvery or coppery appearance. The color of the spot weld will vary by the alloy of the metal being welded and the type of electrodes used to create the spot weld.

An inert gas weld is built up in a gap between two pieces of metal. The finished weld is humped up above the base metal and is easily visible. The high amount of heat generated by inert gas welding can cause the base metal to warp and twist.

Terms and Definitions Reminder about Welding:

Automatic Welding is performed with automatic equipment that requires no controls adjustment by an operator.

Braze is the joint resulting by heating an assembly to the brazing temperature using a filler metal whose liquidus is higher than 450 0C (840 0F) and lower than the solidus of the base metal.

Double Welded Joint is a fusion welded joint that is welded from both sides of its thickness.

Friction-surfacing, a modification of friction welding, is a solid state process whereby layers of various metals are deposited upon a metallic substrate.

Gas Cylinder is a portable container used to store and transport compressed gas.

Hot Pressure Welding is a solid state welding process that produces a weld by application of heat and pressure sufficient to cause macro deformation of the base metal.

Reduced Section Tension Test is performed on a specimen where, in the middle of its reduced section, is located a transverse section of the weld.

Thermite Welding is a process that realizes joining of two parts by fusing them together with heat and filler metal given off by superheated molten metal from exothermic reactions, poured in a mold assembled around the joint.

Highlights On Mig Welding

Feed welding is the other popular name for Mig (Metal insert gas) welding. Other popular names for this weld technique in weld industry are like Gas Metal Arc Welding (GMAW or Metal Active Gas (MAG). It is one of the fastest and simplest techniques of weld.

The method of welding is semi-automatic or automatic. With the helping of welding gun wire electrode and a shielding gas is fed into it continuously. Apart from this Argon gas is also conceded in welding gun along with the wire electrode. This is done so as to achieve the desired results. This technique is mostly employed in high production and welding operations.

MIG welding operation can be carried on metals such as stainless steel, copper, carbon steel, and aluminum. All these metals can be weld in this process and moreover it can be performed in every position with the help of shielding gas, electrode, and welding conditions. This weld technique is popular in automobile industries. The gas which is fed in it acts as a shield agent protecting the weld zones from the contaminants of air borne. While performing this weld operation welder has to follow safety tips to protect him and others too.

Welding Hose Overview

• All units in the machine should be equipped with back-flow prevention and flash back arrestors.
  


• Welding Hose should be check before you use.


• Oxygen and acetylene hose shall be fastened together with approved clamps at
  period of three to four feet along the hose.


• Take Care of hose from being damaged.


• Welding Hose shall be fastened to the regulators and torches by approved fittings only. It is important that all connections be kept tight.


• Use Welding hose and connections made especially for gas welding and cutting.
  
  
  
  • Red colored welding hose can be used for acetylene or other fuel gas
  
  
  • Green colored hose for oxygen.


• Care shall be taken that the hose does not become kinked or tangled. Place the hose
  so that it will not be trampled on, run over or present a tripping hazard.


• Examine welding hoses for defects before use. Defective hose shall not be used.

Gas Welding Safety

Storage and Handling

• Keep cylinders away from physical damage, heat, and tampering.
• Securely chain equipment to prevent falling.
• Store away from flammable and combustible materials.
• Store extra gas and oxygen cylinders separately.
• Store in an upright position.
• Close cylinder valves before moving.
• Protective caps or regulators should be kept in place.
• Roll cylinders on bottom edges to move—Do not drag.
• Allow very little movement when transporting.

General Gas Welding Safety Tips

• Inspect equipment for leaks at all connections using approved leak-test solution.
• Inspect hoses for leaks and worn places.
• Replace bad hoses.
• Protect hoses and cylinders from sparks, flames and hot metal.
• Use a flint lighter to ignite the flame.
• Stand to the side (away from the regulators) when opening cylinder valves.
• Open cylinder valves very slowly to keep sudden high pressures from exploding the regulators.
• Only open the acetylene cylinder valve 1/4 – 3/4 turn; leave wrench in place so the cylinder can be quickly closed in an emergency.
• Open and light acetylene first, then open and adjust oxygen to a neutral flame.
• Follow the manufacturer's recommendations for shutting off the torch. If the guidelines are not readily available, the common accepted practice is to close the oxygen valve first.
• When finished, close cylinder valves, bleed the lines to take pressure off regulators, neatly coil hoses and replace equipment.
• Have a fire extinguisher easily accessible at the welding site.

Personal Protective Equipment:

• Infrared radiation is a cause of retinal burning and cataracts. Protect your eyes with safety glasses.
• Protect your body from welding spatter and arc flash with protective clothing. Such as:
• Woolen clothing
• Flame-proof apron
• Gloves
• Properly fitted clothing that is not frayed or worn.
• Shirts should have long sleeves.
• Trousers should be straight-legged and covering shoes when arc welding.
• Fire resistant cape or shoulder covers are needed for overhead work.
• Check protective clothing equipment before each use to make sure it is in good condition.
• Keep clothes free of grease and oil.

Proper Ventilation
Be sure there is adequate ventilation available when welding in confined areas or where there are barriers to air movement. Natural drafts, fans and positioning of the head can help keep fumes away from the welder’s face.

Ventilation is sufficient if:

• The room or welding area contains at least 10,000 cubic feet for each welder.
• The ceiling height is not less than 16 feet.
• Cross ventilation is not blocked by partitions, equipment, or other structural barriers.
• Welding is not done in a confined space.

**If these space requirements are not met then the area needs to be equipped with mechanical ventilating equipment that exhausts at least 2000 cfm of air for each welder, except where local exhaust hoods or booths, or air-line respirators are used.