FASTENER SAFETY 

PRESENTATION OUTLINE

I.                  INTRODUCTION

A)      Forces Acting Upon Fasteners. (diagrams)

B)     Stress & Strain  (diagrams)

C)     Torque  (diagrams)

II.               IDENTIFICATION OF FASTENER GRADES

A)     SAE / ASTM Grades and Markings (illustration & samples)

1.     steel

2.     stainless steel

3.     bronze

B)     ISO Metric Property Class Markings (illustration & samples)

C)     Manufacturers’ Identification Markings (illustration & samples)

D)     Physical Demonstration (using Torque-Tension-Testing machine to show approx. expected clamp loads)

1.     Grade 2

2.     Grade 5

3.     Grade 8

4.     12.9

III.           IDENTIFICATION OF MATCHING COMPONENTS

A)     Nut Grades and Markings (illustration & samples)

1.     Standard hex, lock and flange

2.     Steel, stainless steel

3.     Inch, Metric

B)     Flat Washers (illustration & samples)

1.     Wrought vs. hardened

2.     Markings

3.     Correct use of SAE Vs USS

IV.            MAJOR REASONS FOR FASTENER FAILURES

A)     Overloading (illustration & samples)

1.     Identification & Correction

2.     Accidental lubrication

3.     Incorrect torque

4.     Incorrect fastener, size and hole

5.     Power wrench use

6.     Heat

B)     Underloading (illustration & samples)

1.     Identification & Correction

2.     Insufficient torque

3.     Embedment into softer materials

4.     Joint relaxation

5.     Gasketed joints not properly tightened

6.     Debris in threads or tapped hole

7.     Reuse of fastener components

C)     Comparison Chart for Fastener Strengths (illus)

1.     Fine thread Vs coarse thread

2.     Rolled threads Vs cut threads

D)     Other Reasons for Failures (illus & samples)

1.     Stress-Corrosion cracking

2.     Liquid metal Embrittlement

3.     Hydrogen Embrittlement

4.     Non-parallel joints

5.     Shear; single & double

6.     Burrs

7.     Bolt length; too long, too short

V.               INSTALLATION & TORQUE TECHNIQUES

A)     Why a Nut Should Never Be Reused (demonstration)

B)     Principles of Torque

1.     Calculations using Proof Load

2.     Field determinations

3.     Lever & extensions

4.     Friction

C)     The Only Time a Torque Wrench is Accurate

1.     Effects of lubricants (demonstration)

2.     Types of lubricants

3.     Thread stretching or stripping

D)     Multiple Bolt Connections (illus)

E)     Gasketed joints

F)     Torquing the Bolt Head Vs the Nut

G)     Turn-of-the-Nut Method (demonstration)

H)      Power Wrenches

  I)       Lock Washers (illus)

 J)       Lock Nuts (demo)