Information related to Bolted Joints

Photo of a fatigue failure of a bolt Presented below are links to pages on specific topics related to bolted joint technology.We specialise in this subject and have extensive knowledge and experience on the solution of problems related to bolted joints. Please contact us if you think we can be of assistance on a problem that you are experiencing. Click on appropriate link for further information on the subject.

Published articles on bolting related matters 

The Bolt Science Quiz on Bolting 

Glossary of fastener and related terms 
Torque Convertor - Conversion program for torque units 
Methods of Tightening Bolts 
Bolt Tightening and Quality Control 
Case Study - Torque Tightening 
The Jost Effect - Why nuts and bolts come loose!
Strength of Threaded Fasteners 
Bolted Joints containing Gaskets 
Frequently Asked Questions 
The Importance of Preload - The Joint Decompression Point 
Bolt Crosstalk and the need for a Tightening Sequence
Tightening the Nut or the Bolt Head
Use of Two Nuts to Prevent Self Loosening
Untightening of nuts and bolts
When is a back-up wrench needed?
Is a torque value really needed?
Should there be a tolerance on a torque value?
World Standards Day - The importance of standards to fasteners
What is the optimum value for the coefficient of friction of a threaded fastener?
The Reduced Loadability of DIN nuts
ISO68-1 The basic and design thread profiles
The Causes of Non-Linear Torque Tension Relationships during Tightening

Tutorial on the theory of Bolted Joints
Why is a bolt's preload force vital?
How a bolted joint sustains an applied force
What is a Joint Diagram?
Joint Diagram with an external force applied
The effect of a high external force on a joint
The effect of a compressive external force on a joint
The Effect of Joint Deformation loss due to Embedding
Bolt Preload Variation due to the Tightening Method
Bolted Joint Analysis using Preload Requirement Charts

Why nuts and bolts come loose
Poster on why nuts and bolts can come loose
Video - Junker Fastener Vibration Test
Tests on the double nut system of locking
Tests on helical spring washers
Vibrational Detachment of Threaded Fasteners
Non-Rotational Loosening of Nuts and Bolts
Preload Loss from Embedding in Bolted Joints
Preload Loss from Stress Relaxation in Bolted Joints
Bolt Self-Loosening and the Critical Slip Distance
The importance of the grip length to bolt diameter ratio

Information related to screw threads
Historical background to screw threads
Basic Thread Terminology
The Whitworth Thread Form
The British Association Thread Form
The Unified and Metric Thread Forms
Basic Profile of Unified and Metric Thread Forms
Tolerancing of Screw ThreadsPhoto of a fatigue failure of a bolt

Examples of bolt failures
M24 Engine Mounting Bolt Failure 
M16 Bolt Failure 
M12 Bolt Fretting Failure 
Wheel Stud Failures 

Short Bolting - Ensuring sufficient thread engagement 

The Effect of Nut Face Angularity on Bolt Fatigue Life 

The Bolt Science Blog
Review of a technical paper titled 'Self loosening of prestressed bolts' 
Review of a technical paper titled 'Prevention of failures of high strength fasteners in use in offshore and subsea applications' 

Contributed Articles
Talking about Torque by George Lorimer 
Smartools for Fastening by George Lorimer 
Tightening Bolts & Relaxation by George Lorimer 
When in Rome by George Lorimer 
More on Relaxation by George Lorimer 
More Thoughts on Fastening by George Lorimer 
Torque versis Torque+Angle Tightening - a case study by George Lorimer 

Video and Other Material
Video on a Junker Transverse Vibration Test on Fasteners 

2024 January Newsletter - Non-Linear Torque-Tension Relationships during Tightening 
2023 November Newsletter - ISO 68-1 The Basics of the Metric Thread Form 
2023 September Newsletter - Recent Update to ISO Nuts 
2023 August Newsletter - The Reduced Loadability of DIN compared to ISO Nuts 
2023 July Newsletter - The Goldilocks Zone and the Coefficient of Friction of Fasteners 
2023 June Newsletter - The Joint Decompression Point - Why Bolt Preload is Important! 
2023 May Newsletter - What is a Residual Torque Measurement. 
2023 April Newsletter - Case study of fastener issues causing a rail accident 
2023 March Newsletter - Is it okay to use a mild steel nut with a high tensile bolt? 
2023 February Newsletter - Bolt Preload Variation due to the Tightening Method 
2023 January Newsletter - Some bolts are tightened past their yield point. Is this a problem? 
2022 December Newsletter - What is the Best Way to Check the Torque Value on a Bolt? 
2022 September Newsletter - World Standards Day 
2022 August Newsletter - Quality Control in the Tightening of Bolts 
2022 July Newsletter - The use of two-nuts to prevent self-loosening 
2022 June Newsletter - Analysis for a Bolt Fatigue Failure in a Clevis Joint 
2022 May Newsletter - Bolt Self-Loosening and the Critical Slip Distance 
2022 April Newsletter - The Effect of Joint Face Angularity on the Fatigue Life of Bolts 
2022 March Newsletter - Information on Screw Threads 
2022 February Newsletter - When to use a back-up wrench 
2022 January Newsletter - Helical Spring Lock Washers 
2021 December Newsletter - Thread Stripping Case Studies 
2021 November Newsletter - Case Study on a Bolt Self-Loosening Investigation 
2021 October Newsletter - The Joint Decompression Point - Why Bolt Preload is Important! 
2021 September Newsletter - Back to Basics - Why Bolt Preload is Important! 
2021 August Newsletter - Historical Background of Screw Threads 
2021 July Newsletter - The Effect of Joint Face Angularity on the Fatigue Life of Bolts 
2021 June Newsletter - Non-rotational Loosening - Part 3 - Stress Relaxation Loss 
2021 May Newsletter - Non-rotational Loosening - Part 2 - Preload Loss from Embedding 
2021 April Newsletter - Non-rotational Loosening of Threaded Fasteners 
2021 March Newsletter - Is a Torque Value Really Needed? 
2021 February Newsletter - Understanding how much thread should protrude past the nut 
2021 January Newsletter - Background to Bolt Science and a new feature, Ask a Question 
2020 November Newsletter - Should there be a tolerance on a torque value? 
2020 October Newsletter - What is short bolting? 
2020 September Newsletter - Tightening bolts past their yield point 
2020 August - Vibrational Detachment of Threaded Fasteners 
2020 July - How do we know what size of bolt to use? 
2020 May - When is a back-up wrench needed? 
2020 April - The use of two nuts to lock a fastener 
2020 March - Fatigue Failure of an M16 Flanged Bolt 
2020 January - A new approach to the tightness checking of bolts 
2019 December - Problem with loose screws 
2019 November - New Thoughts on Hydrogen Embrittlement of 10.9 Bolts 

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