Visual Inspection Techniques Used In Welding Verification

Posted by johnpreston on August 10th, 2017

There are various ways to inspect and approve welding work, including liquid penetration testing, ultrasonic testing and x-ray testing. However, it is not always feasible to employ these means of testing as they may be too time consuming or expensive. Fortunately, it is possible to visually inspect circumferential welding quickly and easily. This visual inspection technique is a simple form of NDT, or nondestructive testing. When visually inspecting a weld, there are a few specific indicators to look for.

Waste

The weld should not have any waste material, or slag. If some of this material is present, it should be easy to identify and, after cooling, should easily fall away. A MIG weld might have some slag because of the shielding gas, but the waste should not be difficult to remove. A TIG weld should be clean and free of any extra materials or waste. If waste is present, it is likely the material was not fully cleaned before the welding process began.

Distribution

There should be an even distribution of weld material across the joined metals. If there are any obvious or extreme inconsistencies, the quality of the weld might be questionable.

Tightness

The joint in precision welding should be completely tight. This tightness is especially important for welding processes that do not use filler material, such as oxyacetylene welding. If you can see gaps in the weld, there is a good chance that the job hasn’t been done correctly. However, these gaps may not be a problem with other kinds of welding that use filler material, as the process is designed to fill all gaps for aesthetic purposes and to reinforce the weld.

Holes

Porous holes, more commonly referred to as porosity, are a big indicator of a poor-quality welding job. These holes not only indicate substandard work, but can compromise the structural integrity of the material. The presence of oxide coating, dirt or other debris on the base material is a common source of porosity in a weld. Insufficient shielding gas in MIG and TIG welds is also a common cause of these holes.

Strength

Although not strictly a visual test, strength is also a good indicator of the quality of a welding job. Using an electrode rating and filler metal rated higher than the desired strength is a great way to guarantee a strong joint. You can simply ask the welder about these details to determine the strength of the joint without necessarily having to physically test it.

Leak Proof

Finally, a bad tank-welding job is very easy to identify when a tank leaks. Simply spray soap and water from a squirt bottle into the joint. If you see bubbles, there is a leak—and a problem with the weld joint.

It is crucial that you hire the right fabricators for your welding work to avoid any of these problems, and a visual test should be able to identify most issues with the quality of work. You may need more extensive testing if a bad welding joint could seriously compromise health and safety.

For more information visit our website: www.techweld.net.