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Stress Analysis Software and Structural Analysis Software Are Often Limited By Bolt Tension Errors
Over 50 web pages on torque, tension, & bolted joints.

Read about the new technology to more reliably measure actual bolt tension, not just bolt torque. See how a structural design laboratory can verify its bolted joint designs.

NDT Update says:  
" SureBolt outperformed the one-point bolt gauges on every bolt and every test in reliability and accuracy."

Stress analysis is sometimes limited by the manufacturer's capability to control bolt pre-load. Structural design may be affected by the following facts:

1.   Bolt tension instead of  bolt torque. You want to put a known amount of tension into your bolted joint, not just a known amount of torque. Your structural analysis often relies on proper pre-load tension.

2.   Bolt failures. What is the number one reason, stated by bolting experts, for bolt failures? Lack of proper pre-load tension. What are some of the factors that cause pre-load tension errors? This affects a bolted joint design, especially the assumptions in structural analysis software. Did the design work n the laboratory?

3.   Measure tension errors. How can torque wrench errors be measured?  Do these bolt tension errors matter? These errors often affect your structural analysis.

4.   Bolt gage. Your joint's stress analysis can be verified using a bolt gage. What is an ultrasonic bolt gage?  See an animated demonstration of an ultrasonic echo inside of a bolt.  Are bolt gages reliable? Are they easy to use?

5.   Friction. Bolt and nut friction consume over 80% of the torque measurement.  How does the actual tension vary bolt to bolt?  What if you use the same type of bolt? This may affect your structural analysis.

6.   Stress, strain & yield. A stress strain curve can be plotted using SureBolt.  Stress strain and yield.  SureBolt can help you verify your bolted joint design.  Did your bolt reach yield?

7.   Flanges. Flange joints sometimes leak.  Why does the tension in a flange bolt vary so much, bolt to bolt?  How can you tighten each flange bolt to closer tolerances?  How can you use SureBolt on a flange?

8.   SureBolt. How does SureBolt differ from any other ultrasonic bolt gauge? Are the prices similar? (Yes)

9.  Mechanical engineering. This site is a mechanical engineering resource for torque versus tension in bolted joints. SureBolt is a nondestructive testing - NDT - method of measuring bolt tension. Non destructive testing includes the use of ultrasonics.


SureBolt's Whole Echo patented technology greatly increases reliability by using the whole echo instead of just one point. All other bolt gages use just "One Point" (one zero crossing), that leaves you susceptible to peak jumping (20% or more error).  Surebolt is a more reliable bolt gage due to a new patented technology. See comparison table.

Bolt gages have been around for over 20 years. Their "Peak Jumping" problems and challenging learning curves, have kept them from being widely used. When your bolted joint fails or flange leaks, then you find out your one-point bolt gage may have jumped peaks. 

Example, with a lot of training and laboratory testing, NASA has used bolt gages for years. NASA physically takes Polaroid pictures of the echoes before and after tensioning. Then they use their trained human experience to determine if the echo has distorted "too-much". Even after all this, they have to throw away approximately one third of the ET measurements because they are not reliable. When NASA used the SureBolt prototype, no measurements had to be thrown away.

SureBolt gives you a 13.3" TFT, portable PC (Panasonic Toughbook Model 72). The ultrasonic pulser and digitizer are built into the CD ROM and PCMCIA slots. Click here to see the actual SureBolt screens. See the animated DEMO page to see how an ultrasonic bolt gage can measure tension. SureBolt has been used on special high strength titanium bolts to standard "off the shelf" bolts.

For more information, see the main SureBoltTM navigation screen.

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SureBolt FLASH Video Why NASA Used Video Download Animated Demo Tutorial On-Line Torque Errors Technical Info Torque Wrench Specifications+ Prices & Compare Services News

"Echo Time".  See animation below of how to ultrasonically measure the change in bolt tension using echo time.
This animation requires FLASH (version 4 or higher).



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 No more guessing as to which "one point" is the right point.


The FIRST whole echo method (patented DSP Technique).

SureBolt picture

Built into a 
Panasonic Toughbook

Weather proof keyboard.

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Last Modified: September 27, 2011