fastener banner 3A fastener, abbreviated as FSTNR, is hardware that mechanically joins two or more objects together.






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Nomenclature & Symbols

  • \( FSTNR \)  -  fastener
  • \( ANPT \)  -  American National Taper Pipe
  • \( ANPT \)  -  Aeronautical National Pipe Taper
  • \( ANS \)  -  American National Standard replaced with UNS
  • \( BA \)  -  British Association
  • \( BSF \)  -  British Standard Fine
  • \( BSP \)  -  British Standard Pipe
  • \( BSW \)  -  British Standard Whitworth
  • \( \lambda \)  (Greek symbol lambda)  -  elastic modulus
  • \( f \)  -  friction
  • \( ISO \)  -  International Organization for Standardization
  • \( NPT \)  -  National Pipe Thread Tapered Thread
  • \( NPTF \)  -  National Pipe Taper Fuel - Dryseal
  • \( NPS \)  -  nominal diameter
  • \( \tau \) (Greek symbol tau)  -  shear stress
  •  \( f_s \)  -  static friction
  •  \( \mu_s \)  (Greek symbol mu)  -  static friction coefficient
  •  \( \epsilon \)  (Greek symbol epsilon)  -  strain
  • \( \sigma \)  (Greek symbol sigma)  -  stress
  • \( T \)  -  temperature
  • \( UNS \)  -  Unified National Standard
  • \( USS \)  -  United States Standard
  • \( UTS \)  -  Unified Thread Standard
  • \( \sigma \)  (Greek symbol sigma)  -  yield strength


fastener Types

  • Permanent  -  These parts will never be disassembled like rivets and welding.
  • Removable  -  These parts can be disconnected without damaging the fastener like nut and bolt.
  • Semi-permanent  -  These parts can be disconnected, but some damage can occurs to the fastener like a cotter pin.


fastener standards

ASME Standards

  • ASME B1.20.1 - Pipe Threads, General Purpose, Inch
  • ASME B1.20.3 - Dryseal Pipe Threads, Inch
  • ASME B18.12 - Glossary of Terms for Mechanical Fasteners
  • ASME B18.18 - Quality Assurance for Fasteners


Fastener Glossary


  • Alloy steel  -  A steel that one or more elements (other than carbon) have been added.
  • Annealing  -  A process of heat treatment that changes the properties of metals.


  • Bolt  -  A fastener with a head and threaded on one end only.
  • Bolt head  -  Formed by heating the end of a round piece of steel round bar then forged in to a head shape.
  • BSF  -  British Sandard Fine
  • BSW  -  British Standard Whitworth


  • Cold forming  -  A material is placed between two dies and compressed into a shape.
  • Corrosion resistant  -  The ability to resist corrosin under certain conditions.
  • Cut thread  -  A threading method produced by removing material from the surface with a form cutting tool.


  • Deformation  -  Is measured by how much an object is deformed from its origional dimensions.


  • Effective diameter  -  See pitch diameter.
  • Elastic modulus  -  The ratio of the stress applied to a body or substance to the resulting strain within the elastic limits.
  • External thread  -  A screw thread that is formed on the external cylinder.  Also called male thread.


  • Fastener length  -  Measured from the top of the head to the bottom of the threads.
  • Force  -  The push or pull of an object resulting in a change from rest or motion.
  • Forging  -  The process of forming raw steel by displacement under force into specified shapes.
  • Friction  -  The mechanical resistance to the relative movement of two surfaces.



  • Hex head bolt  - A bolt with six sided head.
  • Hex head cap screw  -  A hex head screw with a flat and washer faced bearing surface under the head.


  • IFI  -  Industrial Fasteners Institute
  • Internal thread  -  A screw thread that is formed inside a hole.  Also called female thread.




  • Left hand thread  -  A screw head that rotates counterclockwise.
  • Lock nut  -  Resists loosening under vibration and torque.



  • Major diameter  -  The largest diameter of a screw thread.
  • Minor diameter  -  The smaller diameter of a screw thread.
  • Nominal diameter  -  The external size diameter designated of pipe or threads.



  • Pitch diameter  -  See thread pitch diameter.


  • Quenching  -  A process of quickly cooling an elevated temperature.


  • Right hand thread  -  A screw head that rotates clockwise.


  • Shank diameter  -  The smooth part of the bolt above the threads.
  • Shear stress  -  Tends to deform the material by breaking rather than stretching without changing the volume by restraining the object.
  • Strain  -  The deformation, stretched or compressed, of a material compared to its original length.
  • Stress  -  The force per unit area of cross-section.


  • Tap bolt  -  A bolt that is threaded to the botom of the head.
  • Tension strength  -  The capacity of a material to resist a force tending to stretch it.
  • Thread angle  -  The angle between the thread flanks.
  • Thread axis  -  The imaginary distance equally between the major and minor diameters.
  • Thread count  -  The number of threads per inch (TPI), used for US threads.
  • Thread crest  -  The peak of a thread at the major diameter.
  • Thread flank  -  The side of a thread between the major and minor diameters.
  • Thread height  -  The perpendicular distance between the major and minor diameters.
  • Thread length  -  Length of the cylinder that is threaded.
  • Thread pitch  -  The distance between threads measured in millimeters, used for metric threads.
  • Thread pitch diameter  -  The imaginary diameter equal distance between the major and minor diameters.  Also called effective diameter.
  • Thread root  -  The bottom of the thread.
  • Torque  -  A rotational moment.


  • UNC  -  United National Course
  • UNEF  -  United National Extra Fine
  • UNF  -  United National Fine
  • UNR  -  United National (UN)





  • Yield point  -  The point where an elastic material is permanent change in length with no extra load force.



Display #
Aerotight Nut
Anchor Bolt
Angle Controlled Tightening
Anti-friction Coating
Anti-seize Compound
Autolock Nut
Band Hanger
Basic Thread Profile
Beam Clamp
Black Bolts and Nuts
Bolt Grip Length
Bolt Identification Marking
Bolt Inch to Metric
Bolt Nominal Length
Bolt Stud
Bolt Torque
Bolt Wrench Size (in)
Bolt Wrench Size (mm)
British Standard Fine
Bump Thread
Center Beam Clamp
Clevis Hanger
Compression Spring
Compression Strength
Decompression Point
Direct Tension Indicator
Extension Spring
External Thread
General Information about Fasteners
Hooke's Law
Internal Thread
Leaf Spring Stiffness
Lefthand Thread
Linear Spring Shear Stress
Moment Arm
National Pipe Thread
Nut Runner
Spring Diameter
Spring Displacement
Spring Energy
Spring Index
Spring Load
Spring Mean Coil Diameter
Spring Number of Active Coils
Spring Pitch
Spring Potential Energy
Spring Rate
Spring Solid Coil Height
Spring Tension
Spring Travel length
Spring Wire Diameter
Spring Wire Length
Spring Wire Stress
Thread Pitch
Torsion Spring
Wahl Correction Factor