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Complementary fastening elements

Nuts and washers
for reliable joints

Fastening elements selected according to the bolt, the bearing surface and the installation demands of each joint.

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Fastening assembly
Industrial bolted assembly with heavy hex nut and hardened washer

Selected as an assembly

Standard · size · installation

F436
F959

Nuts

The standards that define the assembly.

The nut must be compatible with the standard, grade and dimensional system of the bolt.

ASTM A194 Grade 2H nut with RYC marking
ASTM A194 · Grade 2H
ASTM A563 Grade DH nut with RYC marking
ASTM A563 · Grade DH
01

ASTM A194

2H · 4 · 7 · 7L · 8 · 8M

Nuts for industrial service where the assembly specification calls for an ASTM designation.

02

ASTM A563

A · B · C · D · DH · C3 · DH3

Carbon and alloy steel nuts for structural and mechanical applications.

03

SAE J995

Grades 2 · 5 · 8

Nuts for inch-series bolts, selected according to the grade of the bolt.

04

ISO 898-2

Metric system

Specifies the mechanical properties of nuts for metric bolts.

05

ISO 4032:2023

Metric dimensions

Current international standard for the dimensions of metric hexagon nuts.

06

DIN 934

Historical reference

Formally withdrawn in 2002, although industry may still call for it.

Washers

Every bearing surface calls for a technical decision.

The washer type must match the bolt, the geometry of the joint and the tension control method.

01

ASTM F436

Round hardened washer marked F436 for structural joints

Hardened washers

Heat-treated hardened washers, from 1/4″ to 4″ in diameter, for structural and general use.

  • Compatible with A325, A490, A449, A354, A193, A320 and F1554
  • Available for applications under specification
02

ASME B18.22.2

Square bevelled ASTM F436 washer for sloped surfaces

Bevelled washers

Square bevelled washers that create a proper bearing surface on sloped surfaces, such as the flanges of structural sections.

  • Medium-carbon or alloy steel
  • Quenched and tempered · 38–45 HRC when hardened
03

ASTM F959

Direct tension indicator washer marked ASTM F959

DTI washers

Direct tension indicator washers, from 1/2″ to 1-1/2″, that help guarantee the minimum preload of the bolt.

  • Grades compatible with A325 and A490
  • Available in two types depending on the application

Preload control

DTI: direct tension for critical joints.

ASTM F959 covers direct tension indicator washers for structural connections.

Set of DTI washers with Squirter silicone indicator for preload inspection
DTI Squirter · visual verification
  1. 01

    Guaranteed actual tension

    They measure the elongation of the bolt, not only the torque applied.

  2. 02

    Fast visual inspection

    They allow checking with a feeler gauge or by silicone expulsion (Squirter).

  3. 03

    Less influence from friction

    Rust or missing lubrication does not distort the reading the way it distorts torque.

  4. 04

    Efficiency on site

    They cut inspection time and the need for costly calibration equipment.

  5. 05

    Structural safety

    They help avoid joints that are under-tensioned or over-tightened.

Selection criteria

Three facts worth confirming before quoting.

  1. 01

    Compatibility of the assembly

    Define the standard and grade of the bolt before selecting the nut and washer.

  2. 02

    Bearing surface

    Review the geometry of the joint: a sloped surface may call for bevelled washers.

  3. 03

    Installation method

    For critical structural joints, confirm whether the project requires direct tension control.

Technical support

Need to define the right nut or washer for your joint?

Share the bolt standard and size, joint type, finish, quantity and installation conditions. Our technical team will review the requirement.