|
The Point For (Re-) Certification
By
Andre Odermatt
President, Hobart Institute
Welders are certified to determine if they
can deposit sound welds in accordance with standardized
requirements by various welding codes such as AWS, ASME, API,
Military Standards and more. (See
The World of Welding,
Fall 2004, page 17.) When a piano player does not play for
a long period of time, he or she needs to practice again to
achieve the artistic level once enjoyed because part of the
muscle memory got lost! (See also
The World of Welding,
Spring 2005, page 12). Welders who have not practiced their
techniques experience similar loss.
The other day, I walked by the office of
one of our instructors who had the weld specimens (figures 1 and
2) on his desk. The pieces came from a re-certification test of
a welder who had not welded for over 3 years. My curiosity
about what went wrong here took over and I spoke to several of
our instructors to try to determine the cause of this terrible
failure of a test.
The test concerns a vertical up TIG welding
test on .030 stainless steel. As can be noticed, soon after the
start the welder missed the joint and deposited the filler metal
to the left of the joint on the plate. He missed the joint over
a length of 4 inches of the total length of 8 inches. His view
was obstructed possibly by the left hand feeding the filler
metal. His angle to view the arc, as well as the distance from
the eye to the arc, changed as he proceeded up with the weld.
This probably caused a change of the torch angle and a loss of
some gas coverage as evidenced by the black spots. His irregular
travel speed caused the variability in bead width and bead
height. After 3 days of intense supervised training by one of
our instructors, this formerly certified welder was able to make
an acceptable weld that passed the x-ray test. An acceptable
weld meets specifications. Figure # 3 shows a satisfactory weld
on the same test specimen. The bead is narrower, the ripples
more regular, and this weld used less filler material! If the
welder per figures # 1 and # 2 still has the required dexterity
and vocational competency, he should be able to create a weld
per picture # 3 with an additional two weeks of intense training
by a good instructor. After that he should continue to strive
for the perfect weld!
“If you think this is bad, you haven’t seen
anything yet,” explained one of our instructors who deals
regularly with the certification of welders. He showed me the
weld specimen per Fig. 4.
A welder called our institute some time ago
to take a certification test for stick electrode welding
according to
American Welding Society (AWS) D1.1 Structural
Welding Code. He claimed he was a welder and expected to
make more money if he had passed this test, which is, in all
probability, correct. The process chosen was manual stick
electrode. The test is documented in an AWS QC-7/D.1.-98
Prequalified Welding Procedure Specification (WPS).
The specimen depicts a one-inch plate, 45
degree included angle, vertical up position. As the picture
illustrates, there are many problems with this weld, caused
primarily by wrong operator technique and a complete lack of
understanding of the process. The incomplete fusion, or lack of
fusion as it is sometimes referred to, is evident on both sides
of the weld and caused by improper travel speed, possibly a too
low current setting and the wrong electrode angle. The
inclusions are probably caused by improper cleaning between
passes and erratic travel speed, but may also be attributed to a
weaving motion that is too wide and/or letting the slag run
ahead of the arc. The poor penetration is probably due to an
excessively high travel speed and an exceedingly low welding
current. The porous weld points towards excessively long or
short arc lengths.
We at HIWT are deeply saddened by the fact that there are many
welders with lack of proper training, causing the industry
astronomical sums of money in scrap, rework and warranty
expenses. According to a survey made by the Federal Reserve Bank
of Philadelphia, factory applicants are lacking the skills
needed to do the job. Skills employers said lacking are: use of
production machines or tools 76.4 %; specific plant and system
operator skills 50.9 %; basic skills (reading, writing, math)
40.0 %. From another survey of 223 key manufacturers and
fabricators we learn that the number one concern was the lack of
trained welding operators and secondly the lack of operator
training.
The welder who created figure 4 was (maybe still is) employed as
a welder! There are welders and there are those who think they
are welders. Have I made my point for certification and
re-certification?
Reference:
HIWT
Pocket Welding Guide, 27th edition, EW 609.
Federal Reserve Bank of Philadelphia, Survey of Manufacturing
Employees.
|
