Container Repair- Welding (Container Welding)

 

Welding Methods:        

Selected repair Method should be most economical. Since, we said the straightening is the most economical repair method (Repair Procedure), the second most economical container repair method is welding or straightening and welding. Priority should be straightened or welded rather than removed, inserts, sections, or replacement of components.

 

Welding: 

It uses heat to fuse two separate pieces of metal into a third piece of metal. (Safety precaution of welding) Welding work must be carried out and supervised by qualified welders. Use of materials equivalent to those used to make the original equipment. Ensure that the minimum yield strength of the welding rod or wire is at least 46 kg/mm² or 65,000 psi. If the welding material is unknown, follow the recommendations. (Welding rods)

Integrity of weld:

Welding should conform to requirements of recognized technical societies such as American welding society, British standards etc. (Welding inspection)

Integrity of welds usually can be verified by visual inspection. A magnifying glass is useful. The inspection should determine that the weld is:

1) Watertight

2) Free of porosity.

3) Smooth in appearance.

4) Craters free.

5) No weld spatters.

6) Dimensionally accurate.

7) Free of undercutting.

The inspector should inspect and verify complete penetration of the weld. If welding of one side of the joint does not lead to complete penetration of the joint, both sides of the joint must be welded. (Welding jobs).

 

Sophisticated Procedures:

The visual inspection procedure described above should not replace a more complex procedure, if needed, for the repairer to be satisfied with weld quality.

Non-destructive testing methods based on magnetic particles, penetrant testing, radiation, or ultrasonic eddy currents are available, but these methods can exceed the capabilities of many repair shops. (Welding procedure).

 

Limitation of Welding or Straightening and Welding:

    Fractures, cracks, cuts or tears in a component in many cases, be repaired by welding or a combination of straightening and welding. The following limitations apply: (Welding Criterion).

1)             The maximum length of any crack, fracture, cut or tear that may be welded is 200 mm (8 in), and the maximum width of separation is 5 mm (3/16 in).

2)               A crack, fracture, cut or tear may not be welded if it penetrates more than 50% of the height of a rail, crossmember or another horizontal structural component.

3)                If the gap between the damaged edges is too great to meet the acceptable separation criterion, or if a crack is either too long or too wide as indicated above, even after straightening, then the damage area must be removed and fitted with an insert, section or replacement component as appropriate.

If welding up a crack, drill stop holes at each end of the crack to prevent it from propagating.

 

Advantages of welding:

Welding is the fastest way, no need to waste time, cutting or aligning holes. If you have and skills to use the equipment, weld easily. Therefore, welding is ideal for structures that cannot be dismantled.

Disadvantages of welding:

Sometimes weld materials are low quality that occurs various problems. Repairman should check and ensure the materials.

The cut off welds need to be cleaned, primed, and painted again.

 

Kinds of weld:

Common Weld: A single weld joining together two adjacent insert or section on one side of each.

Continuous Weld: A single, unbroken bead of weld used to join and seal two steel components together completely.

Tack Weld: A bead of weld less than 25mm in length.

Stitch Weld: A liner series of weld beads, each of which is approximately 25mm or more in length and separated from the next bead by an unwelded length. (Welding tools).

Arc Weld: Arc welding uses an electrical current to weld metals. Types of arc welding include metal inert gas (MIG) welding and tungsten inert gas (TIG) welding, among others. (MIG vs TIG)

MIG: Metal Inert Gas, a method of weld. MIG welding is usually used for large and thick materials. It uses consumable wires that act as electrodes and fillers. This is much faster than TIG welding, which reduces lead times and lowers production costs. It's also easier However, welds are not as precise, strong, and clean as TIG welding. (Mig welding)

TIG: Tungsten Inert Gas, a method of weld. TIG welding is so flexible that industry professionals can join a variety of small and thin materials. Non-consumable tungsten electrodes are used to heat metal and can be used with or without fillers. Compared to MIG welding, it is much slower, often resulting in longer lead times and greater production costs. (Tig welding)

Upon completion of any repair that damage the original surface coating, the repaired area must be cleaned and smooth.