Chapter 29 Shielded Metal Arc Welding 813
Copyright Goodheart-Willcox Co., Inc.
an oxyfuel torch or applied in a furnace. The purpose is to relieve stresses
and slow the cooling process. Welded casting can also be cooled slowly after
welding by covering it with or burying it in insulating material, such as lime
or vermiculite. Cooling parts should be left undisturbed until they reach
atmospheric temperature.
Peening the weld with a ball-peen hammer immediately after welding
expands the weld metal to counteract the effects of contraction. Longer
sections of cast iron can be welded by making short welds with soft nickel
electrodes followed by peening while the initial cooling takes place.
Welding Certifi cation
Welding certifi cation is written documentation that a welder has
produced welds according to certain standards. The welder must perform the
test under supervision and following prescribed conditions. Certifi ed welders
are considered desirable by potential employers and can often command
higher salaries than uncertifi ed coworkers. Ability to certify also indicates a
willingness to commit to a goal. However, not all welders need to be certifi ed.
Many agricultural jobs require only occasional welding.
Different certifi cation tests are administered for variances in type of
material, thickness of material, welding position, intended use, and other
factors. However, if written correctly, a single test may qualify a welder for
several positions and thicknesses. For example, persons certifi ed in vertical
welding are often considered certifi ed to weld in the fl at and horizontal
positions as well.
Certifi cation tests are almost always based on a welding code and
follow an approved welding procedure specifi cation (WPS), a document
that outlines the parameters or conditions of the test. The completed
weld must meet visual inspection criteria as well as pass destructive and
nondestructive testing.
Companies that need certifi ed welders often hire third-party companies
to administer certifi cation tests. If a certifi ed welder changes jobs, even within
the same company, a new certifi cation is usually necessary because the
company is legally responsible for the quality of welded joints. Certifi cation
by this method is generally not portable, or transferable, from one company
to the next. However, previous certifi cation is a competitive advantage when
applying for jobs.
Certifi cation testing is available at AWS-accredited test facilities. The
resulting certifi cate is slightly more portable than a test performed for a
specifi c company.
Many schools offer training programs that lead to certifi cation, and most
offer some type of certifi cate of completion. This is not welding certifi cation;
however, it indicates that a person is prepared to be tested. A welding
certifi cation test does not necessarily involve a diffi cult weld joint; however,
most welding tests are challenging. If you know what the test will be ahead
of time, practice is in order.