Identical bolts, when tightened to
identical torque
values, will vary substantially in their actual tensions (typically plus or minus
25%, and not uncommonly plus or minus 50%).
Why? Because 85% of your torque is
consumed by friction. Then this friction varies on EACH
bolt (even the same bolt at different times). Flange
bolts' tensions easily vary 50% or more.
Note: New ultrasonic invention cannot be fooled by friction variations.
See ultrasonic video.
Friction has always
been the
problem. See why NASA's Space Station
engineers used the new technology called SureBoltTM.
Press---here, to go to the
main information page for bolt tension, torque, ultrasonic solutions,
..., etc.
See
which section below is the best way for you to find the information you want. Each section has useful information on friction, torque wrench errors, bolt
failures, bolt gage, stress, strain, yield, and flanges. Press here
for the main SureBolt page. There are even outside links to the web's best bolted joint
tutorial.
A. Mechanical engineering departments often
teach their mechanical engineers to design bolted joints by calculating bolt
tension, not bolt torque. Yet, mechanical engineers
using stress analysis software and structural analysis
software are often limited by bolt tension errors. See a FLASH animation of this
new technology to measure actual bolt tension,
not just bolt torque.
B. After all the mechanical engineering,
structural engineering, and civil
engineering classes on stress analysis calculations, why do some bolted
joints fail? Here is a list of information that may be useful for a
bridge designer, flange designer, torque wrench
user, bolted joint designer, or engineering lab using structural
analysis software, stress analysis software, or bolted joint design software.
C. New NDT
& NDE Technology Advances Bolted Joint
Design. New NDT
& NDE Technology Advances Bolted Joint
Design. New DSP technology, PC technology, and
ultrasonic technology combine to measure actual bolt tension,
not just bolt torque. Nondestructive testing new
technology.
D. Stress analysis
software and structural analysis
software packages are often limited by bolt tension errors.
E. Flanges. After all the engineering classes on flange design,
why do some flanges leak?
F. Bolt & Nut
Tension, not bolt & nut torque.
Why do bolts fail and flanges leak? Bolt tension
errors become one of the main factors.
After all the engineering classes on
bolt & nut
selection,
why do some bolts fail? After all the American Society
of ... procedures, why such errors?
DSP technique more reliably measures actual bolt tension,
not just bolt torque. New patented
technology.
Press---here, to go to the
main information page for bolt tension, torque, ultrasonic solutions,
..., etc.
This site tries to give you some answers to bolting problems. Even an engineering lab
will find this site a good resource for their students. Remember, a
torque wrench with a bolt gage, can help prevent bolt failures and flange leaks.
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Visitors Since 1-22-02
Last Modified:
March 24, 2007
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