penetration are deformations of the
pipe by the thread die forming the root
of the thread.
Measurements of this pipe showed it to
be American National Standard Institute
(ANSI) Schedule 10 pipe. The pipe thread
used was an American National Standard pipe thread. The pipe at the right in
Figure 3 is Schedule 40 pipe with the appropriate standard tapered pipe thread. It
is known in the plumbing industry that
Schedule 10 pipe cannot be threaded because the pipe wall thickness is too thin.
Typically, a rolled groove coupling system
is one method of joining Schedule 10 pipe
with other components.
In this particular case, the pipe wall
thickness was reduced significantly by
the improper threading, resulting in
pipe failure and the water loss. Over
time, water pressure variations caused
failure of the pipe due to the thin and
weakened wall cross section. The root
cause of the loss is improper plumbing
construction and installation. Retention
of evidence (valve, failed pipe section),
taking statements of building personnel
and documenting the circumstances will
aid in a successful recovery for the insurance adjuster’s client.
Charles C. Roberts, Jr., Ph.D., P.E., is
president of C. Roberts Consulting
Engineers, Inc., which provides
professional engineering services in
accident reconstruction, failure analysis,
fire causation, explosion analysis, and
biomechanics. He may be reached
at firstname.lastname@example.org. For more
information, visit www.croberts.com.
leakage source and
circumstances of the
leakage is helpful for
those performing a
more detailed analysis
of the problem.
Thread Root Penetration
Failed Pipe Schedule 40 Pipe