_Dezincification.pdf. It's a snapshot of the page taken as our search engine crawled the Web.
The web site itself may have changed. You can check the current page or check for previous versions at the Internet Archive. Yahoo! is not affiliated with the authors of this page or responsible for its content.
T H E F O R E N S I C E N G I N E E R I N G R E P O R T I - E N G - A
®
[
I N - J
U H
]
Lets see now.hmmmm? That works
out to odds of 30,000 to 1. A ratio of
30,000:1 is much better than the aver-
age lotto odds but not so great for the
insurer. When someone, somewhere,
uses an incorrect pipe fitting costing $3
and the use of the incorrect fitting results
in $90,000 damages it is surely not a
happy day.






In this case the incorrect pipe fitting cost
only $3 dollars. As it happens, the cor-
rect pipe fitting also would cost only
about $3. Both pipe fittings look very
similar, either as common ordinary brass
or bronze. The reason for use of the in-
correct fitting is unknown but not likely
related to the cost of the fitting since
both cost about the same. Most probably
V O L U M E 1 1 , I S S U E 3
T H E F O R E N S I C
E N G I N E E R I N G R E P O R T
I N S I D E T H I S
I S S U E :
Dezinkification
1-2
The Automotive EDR:
Opening Pandoras
Black Box
1, 3

Comedy Relief

2







Recent Recalls

3
A P U B L I C A T I O N O F T H E
I N V E S T I G A T I V E E N G I N E E R S A S S O C I A T I O N , I N C .

A $3 ITEM...A $90,000 LOSS

HAVE NO FEAR... DEZINKIFICATION IS HERE

Continued on Page 2
the use of the incorrect fitting was a
simple matter of inexperience on the
part of the person doing the installation
of the sea strainer. What does matter is
where and how the fitting was used.






The background to this 30,000 to 1 loss
has to do with a $1,000,000 sailing
yacht. This very nice yacht has an auxil-
iary motor for times of non-sail propul-
sion. This auxiliary motor is cooled by
seawater that is drawn into the engine
cooling system through a sea strainer.
Mounted next to the outer hull of the
vessel and below the water line, a fail-
ure of the sea strainer that allows water
to enter unrestricted could cause the
yacht to flood or even sink. In this event

and law-enforcement industries as possi-
ble. The test was completed at the Colo-
rado State Patrol (CSP) Driving Track in
Golden, Colo., with representatives from
the CSP, the Colorado Division of Insur-
ance, and various other insurance provid-
ers present for the test.

The purpose of the test was to evaluate
an EDR in action, comparing the results
with more typical vehicle accident recon-
struction methods in order to gain a better
understanding of the accuracy of the EDR
data. The results of the test would speak
for themselves, allowing PIEs non-
engineering counterparts to witness first-
hand how the EDR data is acquired and
utilized during an accident reconstruction.
A sample of the test results are displayed
in Table 1.

The Automotive EDR (Black Box) has
been the subject of much scrutiny over
the course of the last few years. Many are
skeptical of the accuracy of such a device;
even more are outraged at the possibility
of being spied upon by this technology.
The latter concerns, while an interesting
topic of discussion, will not be addressed
in the context of this article. The former,
regarding concerns of the accuracy and
applicability of EDR data, have been
brought to the attention of the authors on
numerous occasions by numerous people.
PIE decided that a hands-on evaluation of
EDR was necessary in order to address
these concerns.

The idea was simple: conduct a controlled
crash test with the intent of comparing
the EDR data to that of more traditional
reconstruction techniques, and invite as
many representatives of the insurance
T H E A U T O M O T I V E E D R : O P E N I N G P A N D O R A S B L A C K B O X
B Y : P R O F E S S I O N A L I N V E S T I G A T I V E E N G I N E E R S , I N C . ( P I E )
Image of the 90-degree impact of the
test vehicle with the target vehicle.
Note the inflated drivers airbag.


Continued on Page 3 E N G I N E E R S ?
A $ 3 I T E M . . . A $ 9 0 , 0 0 0 L O S S C O N T I N U E D

Page 2
THE FORENSIC ENGINEERING REPORT
water and over time leaches out of the
pipe fitting. As one would easily con-
clude the zinc eventually dissolves out
of the pipe fitting leaving only the cop-
per base material along with some
trace elements. This remaining mate-
rial is very brittle and fractures easily
as occurred in this situation.
A closer view is seen in the Photos P-2
and P-3. Note the spongy appear-
ance of the fractured pipe fitting sur-
face in Photo P-3. The spongy appear-
ance occurs with the migration of the
zinc out of the copper base material of
the pipe fitting.
Sufficiently certain of our suspicion of
the cause and origin of the failure of
this pipe fitting we employed the ser-
vices of a competent laboratory to
complete a chemical analysis of the
pipe fitting and sea strainer body.
The laboratory findings did indeed con-
firm the fitting to be brass and dezinci-
fication did occur as a result of expo-
sure to sea water. This finding was
then reported to the adjuster who now
had opportunity to subrogate back to
the yacht builder.

A man is flying in a hot air balloon and
realizes he is lost. He reduces height and
spots a man down below. He lowers the
balloon further and shouts, "Excuse me,
can you tell me where I am?"
The man below said, "Yes, you're in a hot
air balloon, hovering 30 feet above this
field."
"You must be an engineer," said the bal-
loonist.
"I am," replied the man. "How did you
know?"
"Well," said the balloonist, "everything
you have told me is technically correct,
but it's of absolutely no use to anyone."
The man below said, "You must be in
management."
"I am," replied the balloonist, "but how
did you know?"
"Well," said the man, "you don't know
where you are, or where you're going,
but you expect me to be able to help.
You're in the same position you were
before we met, but now it's my fault."
COMEDY RELIEF CORNER
a pipe fitting broke away from the sea
strainer thus allowing water to enter the
vessel. The vessel consequently
flooded resulting in $90,000 in dam-
ages to pumps, motors and other equip-
ment located in the bilge area of the
vessel.

Our assignment at Trnka Engineers Co.
was to determine the cause of the fit-
ting failure. The cause of the failure
could possibly provide the basis for sub-
rogation of the claim. The evidence, the
sea strainer and pipe fitting, was pro-
vided to us by the adjuster as seen in
Photo P-1. The broken fitting location is
indicated by the red arrow.
(Continued from page 1)
Sea Strainer Pipe Fitting Failure

Article by: TRNKA ENGINEERS
(I-ENG-A MEMBERSEATTLE, WA)
Zdenek Denny Trnka, P.E. or
Tom Pruitt, ARM, ALCM
Ph: 425-746-4478 Fax: 425-746-4183
trnkaz@nwlink.com
Photo P-2
Photo P-3
Photo P-1
The commentary contained in The Foren-
sic Engineering Report is not intended,
nor should it be relied upon, to replace
specific professional advice. We recom-
mend that readers consult their profes-
sional advisors regarding issues raised in
this publication
.
A quick 10x magnification inspection
of the broken pipe fitting gave us
cause to suspect that a brass pipe
fitting was used in the sea water cool-
ing system where bronze, a more ap-
propriate pipe fitting material, should
have been used.

There are many copper based alloys,
however, only a few are suitable for
extended exposure to salt water.
Copper alloys with relatively high zinc
content when exposed to salt water
will succumb to a phenomenon
termed selective leaching or other-
wise known as dezincification. The
phenomenon in this case is that the
zinc, in constant contact with salt wa-
ter, goes into solution with the sea
Note the Spongy Appearance The results of this test illustrate that the EDR data saved
within the subject vehicle is of extreme value to the investi-
gator. When compared with the more traditional recon-
struction techniques, it can be seen that the EDR data is
indeed an accurate representation of the facts of the case.
Obviously, the investigator does not typically have the lux-
ury of a police laser to confirm his findings. However, the
presence of EDR data during the analysis of a case allows
for an additional set of data that can be compared with
other results.

Regarding the potential usefulness of EDR data, it must be
noted that it is not a stand-alone reconstruction technique.
The data, while proven to be reliable and accurate, can
and must be used in conjunction with a complete accident
reconstruction. There are various examples, beyond the
scope of this article, which illustrate the need for interpre