This course is an introduction to bolting technology and includes
key information on the subject. A brochure is available on
this course and can be downloaded by clicking on the link
on the Course on Bolting Technology
The course content includes:
Introduction to Threaded Fasteners
Preload Variation in Threaded Fasteners
- Know the meaning of thread terminology.
- Learn when it is appropriate to use
a fine rather than a coarse thread.
- Be aware of the principal bolt and nut
strength property classes and how they should be specified.
- How to match the nut strength to that
of the bolt so that thread stripping problems are prevented.
- Find out why bolt tensile fracture is
preferable to the threads stripping.
- Learn what the proof load is and why
it is used.
- Be able to identify the meaning of the
markings on bolt heads and nuts.
- Learn about the thread stress area and
how it is derived and used.
- Be able to calculate the tensile strength
of a threaded fastener.
- Understand how a pre-tensioned bolted
joint sustains an applied load.
Galling of Threaded Fasteners
- Learn why there can be such a significant
variation in the preload (tension in the bolt) and the consequences
- How the torque is distributed between
the threads and the nut face when free spinning and torque
prevailing fasteners are used.
- Why preload is so crucial in a bolted
- How preload variation can be accounted
for at the design stage.
- The effect of the tightening method
on the preload variation sustained by a fastener.
- What is galling and what types of materials
tend to be affected?
- Examples of fastener threads that have
galled, sectioned and x-ray photos.
- Four ways that galling can be eliminated.
Methods of Tightening Threaded Fasteners
Have an understanding of the principles
behind each of the following tightening methods:
Failure Modes of Threaded Fasteners
- Torque controlled tightening.
- Torque-angle controlled tightening.
- Yield controlled tightening.
- Bolt stretch method.
- Heat tightening.
- The use of load indicating methods.
- The use of ultrasonics to determine
Vibration Loosening of Threaded Fasteners
- Learn the differences between a manufacturing
and design quality defect.
- Be able to identify whether a failure
is due to a fault in the design specification or is manufacturing
- Learn the 5 main design related failure
modes of threaded fasteners and bolted joints.
- Have knowledge of the critical importance
of a fastener's clamp force in ensuring a joint's structural
- Why the joint design normally prevents
- Learn about fatigue and where failures
normally occur on a threaded fastener.
- Why bearing stress can be crucial in
ensuring a reliable joint.
- Learn about the nature of internal and
external thread stripping failures.
Have an overview of the research completed
over the last 50 years into establishing the cause of self-loosening
of threaded fasteners.
Appreciate the forces that are acting on the threads that
tend to self loosen a fastener.
- Why fine threads
can resist loosening better than coarse threads. The inclined
- Learn about the work completed by Goodier
and Sweeney into loosening due to variable axial loading.
- The work completed by ESNA and the theory
of shock induced loosening and resonance within fasteners.
- The MIL-STD 1312-7 vibration test for
- Junker’s theory on self-loosening
of fasteners and why fasteners self-loosen.
- The Junkers/transverse vibration test
- The influence that vibration amplitude
has on the fastener self-loosening rate.
- Preload decay curves and the effectiveness
of various fastener types in resisting vibrational loosening.
- The findings of Haviland and Kerley
and how fasteners can come loose as a result of bending,
shock or impact and differential thermal expansion.
- Conclusions from the research and how
loosening can be prevented.
- What is meant by a tightening torque?
- Units used to measure torque.
- What are the consequences of not applying
sufficient torque to a bolt.
- How torque is absorbed by a nut/bolt
- The torque-tension graph.
- The relationship between the tightening
torque and the resulting bolt preload (tension).
- The factors which affect the torque-tension
- The nut factor method of determining
the correct tightening torque.
- Example calculation of how to determine
the correct tightening torque.
- Scatter in the bolt preload resulting
from friction variations.
- Determining the bolt preload (tension)
resulting from a tightening torque.
- Prevailing torque fasteners (such as
those containing a nylon insert) and how they affect the
torque distribution and the correct torque to use.
Load Sensing Fasteners
- The use of strain gauged bolts.
- The use of load cells.
- The use of Rotabolts™.
- The use of Smartbolts™.
- The use of direct tension indicators
(load indicating washers).
- Squirter™ direct tension indicators.
- Tension control bolts.
Hydraulic Tensioning of Threaded Fasteners
- The principles behind hydraulic tensioning.
- The number of tensioners that are used
to tighten a joint – 100%, 50%, 33% and 25% tensioning
- The effect of elastic recovery on the
tension induced into a bolt.
- The use of hydraulic nuts and the sequence
used to tighten them.
- The use of oil filled nuts.
- The use of rubber filled nuts.
- The problems of tightening multi-bolt
- Elastic interaction or bolt cross-talk.
- The use of a tightening sequence.
- The single pass tightening sequence.
- Tightening sequences for non-circular
- Tests completed to verify tightening
- The two pass tightening sequence.
- The use of multiple tightening tools.
- Bolt cross talk and hydraulic tensioning.
- Methods that can be used to check the
- The solder plug method.
- The use of pressure sensitive films.
- Establishing a tightening procedure.
- Examples of tightening sequences for
circular joints consisting from 4 to 32 bolts are given
in the handbook together with an example tightening procedure.
A training course handbook is provided that
contains background information to the material presented
in the course, together with appendices containing tables
of thread size details, fastener material strengths and a
glossary detailing the key terms used in bolting technology.
training course is also available now, online, from www.bolting.info