Visible Bolt Tension Control for Structural Connections

Need a practical way to verify tightening in a specified structural bolted connection? Bremick direct tension washers are metric galvanised direct tension indicating washers designed to provide a visible indication as bolt tension develops during installation. Bremick's current range includes M16, M20, M24 & M30 sizes for compatible structural fastening applications.

For structural bolting around Somerville, the Mornington Peninsula & projects across Australia, the complete assembly matters. Browse Bolts & Fasteners for associated fastening hardware or Nuts & Washers when additional washer & nut components are required.

Don't treat a direct tension indicator like an ordinary flat washer. Correct size, orientation, bolt assembly, tightening method & project requirements all need to be established before installation.

What Are Bremick Direct Tension Washers?

A direct tension indicating washer turns bolt tightening into something an installer can physically inspect.

Unlike a conventional flat washer, a direct tension indicator incorporates raised protrusions on one face. As the compatible structural bolt assembly is tightened, those protrusions compress & the resulting gap changes.

That change provides a means of checking whether the specified tightening condition has been reached when the washer is installed & inspected according to the applicable procedure.

Bremick lists its current range as:

► Direct Tension Indicating Washers – Metric – Galvanised
► ASTM F959M product family
► M16
► M20
► M24
► M30

Size selection begins with the structural bolt assembly. A direct tension washer should never be chosen independently simply because its outside dimensions appear suitable.

For broader threaded fastening requirements surrounding the connection, Bolt Bar provides access to bolts, washers, threaded components & related hardware.

Why Choose Bremick Direct Tension Washers?

Structural bolting can require more than tightening a nut until it feels sufficiently tight.

Direct tension indicating washers provide a mechanical indication associated with tension developing in the bolt assembly.

That makes them relevant where the specified installation method calls for direct tension indication.

Key characteristics of Bremick's range include:

► Metric sizing
► M16–M30 options
► Galvanised finish
► Raised indicating protrusions
► Structural bolting application
► ASTM F959M product designation

Their value lies in the installation method rather than the appearance of the washer itself. Selection, placement & inspection need to follow the requirements applicable to the structural connection.

Common Applications

Steelwork is where a small washer can become part of a much larger installation procedure.

Structural Steel Connections

Specified structural assemblies can use direct tension indicators where bolt pretension needs to be established using an approved installation method.

Commercial Construction

Steel frames, fabricated structural members & associated bolted connections can call for controlled structural-bolt installation.

Industrial Steelwork

Platforms, access structures, equipment supports & fabricated industrial assemblies can contain structural bolted connections requiring specified tightening procedures.

Infrastructure Work

Selected bridge, civil & infrastructure steelwork can use high-strength structural bolting systems where project documentation determines the fastener assembly & installation method.

Fabrication & Erection

Fabricators & steel erectors may encounter direct tension indicators when preparing or installing structural connections specified for pretensioned bolts.

Maintenance of Existing Steel Structures

Replacement work can require the original or current engineering specification to be checked before structural fasteners are disturbed or substituted.

Never select the tightening method from habit alone. Drawings, engineering requirements, fastener specifications & applicable installation procedures should determine what belongs in the joint.

For crews working around structural maintenance, the Quarry Crews Crusher Maintenance article provides a practical look at maintenance where fastening, equipment condition & downtime all matter.

Product Selection Guide

The washer diameter is only the first checkpoint.

Start with the structural connection specification then work down to individual components. Mixing apparently similar bolts, nuts & washers without confirming compatibility can change the intended assembly.

How Direct Tension Indicating Washers Work?

The small raised areas on the washer are there to move.

When correctly installed, the protrusions are compressed as tightening progresses.

The reduction in the gap associated with those protrusions provides the installer or inspector with a physical indication related to bolt tension.

A typical installation process requires attention to:

► Washer position
► Protrusion orientation
► Structural bolt type
► Nut & hardened washer arrangement
► Snug-tight condition where required
► Tightening sequence
► Gap measurement
► Final inspection criteria

Don't improvise the acceptable gap. Use the requirements applicable to the specific direct tension indicator, structural bolt system & project.

Direct Tension Washer vs Standard Washer

Both components may be round with a hole through the middle, but their jobs are fundamentally different.

Never substitute one for the other because the nominal diameter matches. Direct tension indicators are functional components of the tightening procedure.

For more background on how individual fastening components influence the complete connection, read Why Good Fasteners Matter.

Correct Washer Orientation Matters

Turning a specialised washer over can change how the installation method works.

Australian structural-bolting guidance describes load-indicating washers being positioned so their protrusions bear against the underside of the bolt head, or against an appropriate structural flat washer where the installation procedure requires a different arrangement.

The precise configuration depends on how the bolt assembly is being tightened.

Before installation:

► Identify which component will rotate
► Confirm DTI orientation
► Check whether an additional hardened washer is required
► Verify the structural bolt assembly
► Follow the specified tightening procedure

Don't copy another connection without checking the detail. Similar-looking steel joints can have different assembly requirements.

M16, M20, M24 or M30?

A larger steel connection doesn't automatically tell you which DTI belongs in it.

Bremick currently publishes four metric galvanised direct tension indicator sizes:

Match nominal size to the specified bolt assembly. Don't enlarge, modify or substitute a washer to make it fit a different bolt diameter.

Where a project also requires concrete or foundation fixing systems, Anchor Bolts provides a separate pathway for anchoring steelwork & equipment into suitable substrates.

Galvanised Structural Assemblies

Finish compatibility deserves attention before components are mixed on the erection site.

Bremick identifies these metric direct tension indicating washers with a galvanised finish.

Australian guidance also recognises galvanised load-indicating washers for use with compatible galvanised structural bolt assemblies.

Before assembly, confirm:

► Bolt finish
► Nut finish
► DTI finish
► Structural washer requirements
► Project specification
► Exposure conditions

Avoid making substitutions from appearance alone. A silver or grey finish doesn't establish that two structural fasteners have the same coating, mechanical properties or intended use.

Tightening Sequence Matters

A structural joint containing multiple bolts shouldn't become a race to tighten whichever nut is easiest to reach.

Large connections can require a systematic tightening sequence so the joint is brought together appropriately.

Follow the applicable procedure for:

► Initial fit-up
► Snug tightening
► Tightening sequence
► Final pretensioning
► DTI inspection
► Completion marking where required

Work from the specified procedure rather than workshop instinct. Structural bolt installation is different from general machinery assembly.

For trades wanting a broader grounding in bolt, nut & washer selection, the Fastener Guide covers common fastening families & where their roles differ.

Tools for Structural Fastener Installation

Access around the bolt can become just as important as the fastener specification once steelwork is assembled.

Depending on the approved installation method, crews may need suitable sockets, spanners & inspection equipment.

Toledo | Sockets & Accessories provides supporting workshop equipment for hex fasteners where the selected tool suits the required installation procedure.

Also consider:

► Socket clearance
► Nut access
► Bolt-head access
► Tool capacity
► Inspection access
► Space for gap checking

Designing or assembling a connection without room for installation & inspection can create problems once the steel is in position.

Measuring the Indicator Gap

The final check needs more precision than looking at the washer from a metre away.

Where the applicable DTI installation procedure uses gap measurement, use the specified inspection method & acceptance criteria.

Feeler Gauges can provide controlled gap checking for suitable workshop & inspection tasks, but the gauge size & inspection procedure must come from the applicable DTI requirements.

Never invent an acceptable gap from another washer size or another manufacturer's installation. Follow the documentation for the actual structural fastening system being installed.

Keeping Structural Hardware Organised

A mixed bucket of structural washers, standard washers & direct tension indicators creates unnecessary identification risk.

Keep specialised fastening components separated by:

► Product type
► Nominal diameter
► Finish
► Specification
► Project or connection where appropriate

Tool Storage & Organisation can support workshop or site storage where specialised fasteners need to remain identifiable between delivery & installation.

Leave labels with the hardware whenever practical. Product identification becomes much harder once specialised washers are mixed with visually similar components.

Expert Tips

Check the Bolt Assembly Before the Washer

A DTI can't correct an incorrectly specified bolt or nut.

Verify the complete structural fastener assembly before installation begins.

Keep DTI Sizes Separated

M16 & M20 washers shouldn't depend on someone remembering which bucket they came from.

Store each nominal size with clear identification.

Confirm Which Component Rotates

Installation arrangement can change when tightening occurs from the bolt-head side rather than the nut side.

Check the required washer configuration before applying final tightening.

Protect the Protrusions

The raised indicators are functional parts of the washer rather than packaging bumps.

Inspect them for damage before installation.

Make Inspection Access Part of Setup

A washer can't be checked properly if surrounding steelwork blocks the inspection point.

Consider access before final tightening begins.

Don't Mix Installation Methods

Part-turn tightening, calibrated wrench procedures & direct tension indication aren't interchangeable shortcuts.

Use the method specified for the connection.

Record What Was Installed

Structural maintenance becomes easier when future crews can identify the fastener system already in the joint.

Retain relevant product & installation records where the project requires them.