How to Accurately Measure Fillet Welds method for taking fillet weld readings

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A worker uses the caliper weld inspection method to measure fillet welds in a tubular assembly.
How to Accurately
Measure Fillet Welds
A tubular assemblies manufacturer devised a unique
method for taking fillet weld readings
BY JOE PAVILANIS
Woolf Aircraft Products, Inc., got its
start in Wayne, Mich., in 1942 fabricating
tubular assemblies for B-24 bombers.
Today, the company operates out of a
100,000-sq-ft facility in Romulus, Mich.,
and supplies tubular assemblies for a wide
variety of industries, including defense,
transportation, power generation, and
agriculture. Aircraft and aerospace remain prime segments of the company’s
business, however. Its 125 employees can
fabricate just about any type of tubular
assembly.
Woolf Aircraft has the capability of
bending tubing from 0.125 through 7 in.
in diameter and has a selection of more
than 450 radius dies, which gives its customers many options. It also has an extensive material inventory, stocking more
than 1400 different sizes and types of material. The company commonly fabricates
stainless steel, Inconel™, carbon steel,
chrome-moly steel, aluminum, and titanium, and also has experience with magnesium, Hastelloy® X, AL6XN, and
other exotic alloys. One of the company’s
recent achievements was to become registered to SAE AS9100B, Quality Management Systems — Aerospace — Requirements, in 2008. It has 13 welders qualified
to the requirements of AWS D17.1, Specificiation for Fusion Welding for Aerospace
Applications, in all metals that are fabricated in thickness ranges from 0.020 to
0.250 in. thick, as well as various projectspecific certifications to the ASME Boiler
& Pressure Vessel Code, Section IX, and
an array of customer-specific welding
specifications.
JOE PAVILANIS (joep@woolfaircraft.com) is process/quality engineer, Woolf Aircraft Products, Inc., Romulus, Mich.
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Fig. 1 — The adapter mounts to a digital caliper designed to seat
directly onto the corner of a 90-deg angle.
A
Fig. 2 — The reading gives the distance from the weld root to the
weld face, which is the weld throat.
B
Fig. 3 — A — When touching the weld face, the digital scale shows the actual distance from the root to the face, providing a measurement of
the actual weld throat; B — a close-up of the throat measurement.
Problem/Issue
Many of the weld sizes that Woolf is
required to produce are often less than
0.125 in. and as small as 0.040 in. The company has found that traditional fillet weld
gauges do not work that well for inspecting and verifying the sizes of welds. Even
if you have a custom gauge made as Woolf
has done, it is often so small it is difficult
to make any sort of determination. This
makes the inspection of these welds very
slow and difficult. In addition, it is difficult to obtain actual readings when doing
dimensional inspection reports.
Currently, most gauges that are used
to measure welds are attribute by nature,
which means that they only make a comparison to a template rather than an actual reading. There are some gauges that
will provide a measurement against an imprinted scale to allow an estimation of the
size, but these gauges are not calibrated
and do not offer a variable reading that is
traceable to the National Institute of Standards and Technology (NIST). As a com-
pany that is registered to the quality management systems of ISO9001:2000 and
AS9100B, Woolf must meet the requirement that all measurement systems used
to accept product be traceable to NIST.
Woolf Aircraft needed a tool that
could provide an actual “variable” reading over a range of fillet weld sizes and
be traceable to NIST. Officials there believed that most industries have that same
need; therefore, the company developed
an inspection tool/system that it can use
to measure a leg length, as well as the actual weld throat. With these two known
measurements, this information can then
be used to determine the actual size as
well as the convexity/concavity of a specific fillet weld.
Caliper Weld Inspection
Method
Workers at Woolf Aircraft made an
adapter that mounts to a digital caliper
that has been designed to seat directly into
the corner of a 90-deg angle — Fig. 1. The
digital scale is then set to “zero” and then
used in the same manner against the fillet weld. The reading on the caliper gives
the distance from the “root” (corner) of
the weld to the face of the weld, which is
the weld throat — Fig. 2.
When touching the face of the weld,
the digital scale will reveal the actual distance from the root of the weld to the face,
which is the actual weld throat — Fig. 3.
Using a similar technique to measure
the length of a leg, as shown in Fig. 4, the
individual leg lengths will be determined.
A traditional caliper is used in this
measurement.
Now that the two variables are known
— leg length and actual throat length —
many determinations can be made regarding the weld size. Since the example shown
in Fig. 4 is a 45-deg right triangle, then
both legs should be equal length — Fig. 5.
Applicable Industries
Officials at Woolf Aircraft believe this
measurement system can be useful to a
WELDING JOURNAL
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B
A
Fig. 4 — A — A similar technique, using a traditional caliper, is used to measure the leg length; B — a close-up of the leg measurement.
wide variety of industries besides aerospace, such as military, automotive, commercial, power generation, etc., and that
the entire welding community and every
industry it serves is in need of the ability
to make variable measurements.
This article provides a basic overview
of how the system works. You may have
questions as to how useful it is if your fillet weld is not a 90-deg angle, or if it can
be used to check for misalignment or to
measure weld reenforcement on tube and
pipe groove joints. Options are available
to handle those situations that are not covered in this discussion. Contact the author
for additional information.
Conclusions
This system allows for variable measurement of the weld legs, actual throat
length, calculation of the theoretical
throat length, convexity, and concavity.
Also, by using calibrated digital instruments during the inspection, the inspection system is then traceable to the National Institute of Standards and Technology, which satisfies the expectations of
Fig. 5 — Once the two variables are known, other factors are known about the weld size.
quality management systems such as ISO
9001:2000 and SAE AS9100B. These stan-
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JUNE, 03 WELDING JOURNAL
FEBRUARY 2009
dards require that anything used to accept
product dimensions must be calibrated.
Using this system helps Woolf Aircraft
meet the measurement expectations of
the various quality system requirements
and provide variable measurements without the need for cutting and etching in
order to obtain these measurements.◆
The author would like to thank the following individuals at Woolf Aircraft for
their support in this project and with the
preparation of this article: Adam Woolf;
Al Swistara, vice president, Engineering;
Doug Kochan, toolmaker; Dane
Borowski, tube fabricator; and Adam
Pavilanis, weld engineer intern.