► Hardie Hose | Bushes

Solve Thread Size Mismatches With a Cleaner Connection

One port is too large, the mating fitting is too small & the rest of the assembly is perfectly usable – what actually needs changing? Hardie Hose Bushes provide a compact way to transition between compatible threaded sizes without automatically rebuilding the surrounding hose, valve, regulator or equipment connection.

For maintenance crews, fitters & workshop technicians, the useful question isn't simply “Will it screw in?” Both sides of the bush need to match the intended threads, while material, sealing method & operating conditions also need to suit the system. Identify the connection properly first & the fitting choice becomes considerably easier.

► Compact threaded size transitions
► Options for compatible BSP connection arrangements
► Useful across air, water, hydraulic & general fluid systems
► Practical for repairs, replacements & new installations
► Helps avoid unnecessary chains of fittings
► Suitable for workshop, agricultural & industrial maintenance

Need to change more than the thread size? Compare Hardie Hose | Adaptors for alternative connection configurations.

What Are Hardie Hose Bushes?

A threaded bush solves a very specific problem: two otherwise suitable components need a different size transition between them. Typically, the bush threads into a compatible larger port while providing another threaded connection for the mating component.

That makes bushes useful around equipment such as:

► Regulators
► Valves
► Pumps
► Gauges
► Manifolds
► Pneumatic components
► Hydraulic equipment
► Water-transfer fittings

Small fitting, important decision. Selecting the wrong thread can leave the components unable to assemble correctly or create a connection that isn't suitable for the system.

Why Choose Hardie Hose Bushes?

Keep a Simple Size Change Simple

A thread mismatch doesn't always justify replacing every component around it. Where the application permits, a correctly selected bush can provide the required transition within a compact fitting.

Reduce Unnecessary Fitting Stacks

Combining several adaptors to achieve one reduction can add length & additional connection points. A suitable bush may offer a more direct arrangement.

Useful for Replacement Equipment

New regulator, different port size? Replacement pump, different connection? Bushes can help resolve compatible size differences where the new component & existing fitting use suitable thread arrangements.

Handy Workshop Stock

Common thread transitions can be useful additions to fitting drawers & mobile service vehicles, particularly where technicians regularly work across mixed equipment.

Suitable for New Builds Too

Bushes aren't only repair parts. Fabrication, pneumatic installations & fluid-transfer systems may require planned thread reductions from the beginning.

Common Applications

Regulators, Filters & Workshop Air Equipment

Replacing one pneumatic component shouldn't automatically mean changing every fitting around it. Where a regulator, filter or similar component has a compatible port of a different size, the correct bush may provide the required transition.

For air-line connections & related components, explore Air Fittings & Couplers.

Pumps & Water-Transfer Equipment

Pump ports, valves & adjoining fittings don't always share the same thread size. A suitable bush can provide a compact transition where the specifications correspond.

Hydraulic Maintenance

Machine repairs often expose connection differences only after the old component has been removed. Bushes may form part of compatible hydraulic fitting arrangements where their specifications suit the application.

Agricultural Equipment

Pumps, workshop air systems, machinery attachments & other farm equipment can accumulate different fittings through years of repairs & component replacement.

Gauges & Instrumentation

A pressure gauge or instrument may have a smaller connection than the available equipment port. The correct bush can provide the required transition without an unnecessarily long adaptor arrangement.

Mobile Service Repairs

The machine is already apart & the nearest fitting cabinet is back at the workshop. Carrying commonly required bushes can give field technicians more options when compatible thread-size differences appear on site.

Product Selection Guide

Don't buy a bush from one measurement. You have two connections to identify.

Start With Both Sides

Step 1 – Identify the Equipment Port

Determine the thread size & form of the port receiving the bush.

Step 2 – Identify the Mating Component

Now ignore the first measurement & identify the second connection independently. This is the fitting, gauge, nipple or other component that needs to connect through the bush.

Step 3 – Confirm the Thread Family

Similar diameters don't prove two threads are compatible. Establish the actual specification before assembly.

Step 4 – Check the Material

Consider the bush material alongside the adjoining components, operating environment & medium being carried.

Step 5 – Understand How the Joint Seals

Different threaded arrangements can use different sealing methods. Follow the requirements of the specific components rather than assuming thread sealant is always the answer.

Step 6 – Check the Finished Layout

Make sure the completed arrangement provides suitable clearance & doesn't create unwanted loading on the connected hose or equipment.

Which Fitting Solves Which Connection Problem?

Bushes, adaptors, nipples & hose barbs can all be threaded, but they're solving different problems.

For flexible hose-to-thread connections, browse Hardie Hose | Hose Barbs.

For pneumatic tube installations, Hardie Hose | Push In Fittings provides another connection approach.

Name the connection problem first & the fitting family becomes much easier to narrow down.

Bush or Adaptor – Which Is the Cleaner Choice?

Imagine the port is larger than the fitting you need to install. Do you reduce directly at the port or add another adaptor outside it?

The answer depends on the connection arrangement.

A bush makes sense where the job is primarily a compatible threaded size transition.

An adaptor may be the better choice where thread family, gender, orientation or connection style also needs to change.

BSPP, BSPT & Similar-Looking Threads

“BSP” written on the parts list isn't always the end of the identification process.

Threaded systems can include parallel & tapered configurations, while other thread families can appear deceptively similar at a glance.

Before combining fittings, establish where applicable:

► Nominal thread size
► Male or female connection
► Thread pitch
► Parallel or tapered form
► Intended sealing method
► Mating component specification

A BSPP connection, for example, shouldn't be treated as interchangeable with every fitting that happens to have a similar measured diameter.

Thread identification is a specification exercise, not a visual matching contest.

Why the Ruler Can Mislead You?

Measured the outside diameter & the number doesn't match the BSP size you expected? That doesn't automatically mean you've measured incorrectly.

BSP sizes are nominal, so the stated fitting size isn't simply the physical outside diameter of the thread.

Where identification isn't obvious, use suitable measuring equipment & thread gauges rather than relying on a ruler alone.

A useful process is:

Measure diameter → check pitch → establish thread form → compare specification → confirm mating connection

Never force a fitting because it begins to engage for the first turn or two.

“Nearly fits” is often a warning, not a tolerance.

A Regulator Replacement Example

Here's a common workshop scenario: an old air regulator is removed & the replacement has the right function but a larger threaded port.

Instead of immediately replacing the surrounding airline fittings:

Identify the regulator port
Identify the existing fitting
Confirm both thread forms
Determine whether a suitable bush provides the transition
Check material & application requirements
Assemble using the appropriate sealing method
Inspect the completed installation

Where the difference is simply between compatible thread sizes, a bush may provide a neat solution.

Where the two components use different thread families or connection styles, investigate an adaptor instead.

When a Fitting Stack Becomes a Warning Sign?

Bush into adaptor into nipple into another adaptor? Before reaching for the fourth fitting, reconsider the connection.

An unnecessarily long assembly can affect:

► Equipment clearance
► Access for servicing
► Hose alignment
► Mechanical leverage on the port
► Number of potential leak points
► Overall installation length

Look for the most direct suitable fitting arrangement available.

The goal isn't to use every fitting that happens to be in the drawer. It's to create the correct connection with no unnecessary complexity.

Material Matters Beyond the Thread

Two bushes can share the same dimensions & still not belong in the same application.

Before substitution, consider:

Medium

What fluid or gas passes through the fitting?

Environment

Will the component be exposed to moisture, weather, chemicals or other demanding conditions?

Adjoining Components

What materials are already present in the assembly?

Operating Conditions

What requirements apply to the complete system?

Equipment Specification

Does the manufacturer call for a particular fitting material or connection arrangement?

For a wider selection of threaded & hose components, browse the main Hardie Hose range.

Expert Tips From the Fitting Bench

Keep Both Old Components Together

Don't arrive at the parts drawer holding only half the connection. Having the equipment-side fitting & mating component available makes identification considerably easier.

Write the Transition as Two Sizes

Instead of recording only “BSP bush”, note the complete required size transition & thread details.

Use a Thread Gauge Before Guessing

A gauge can quickly separate fittings that appear almost identical by eye.

Stop When a Thread Starts Binding

A spanner isn't an identification tool. Unexpected resistance can indicate incorrect thread size, incompatible form, damaged threads or contamination.

Check the Port Before Blaming the New Bush

Old fittings can leave damaged, dirty or compromised threads behind. Inspect the equipment port while the connection is open.

Watch for Side Loading

A heavy hose pulling sideways on a fitting can place unnecessary mechanical load on the completed connection.

Organise Workshop Stock by Thread Family

Separate BSP, NPT, metric & other fittings where practical rather than keeping similar-looking parts mixed together.

Diagnose the Connection Before Replacing Another Fitting

The assembly leaks after installation. Is the bush definitely the problem? Not necessarily.

Locate where the problem actually occurs before replacing the next component in the chain.

Before the System Goes Back Into Service

Once everything is assembled, look at the connection as part of the machine rather than as an isolated fitting.

Confirm where applicable:

► Outer thread corresponds with the equipment port
► Inner thread corresponds with the mating component
► Bush material suits the intended application
► Threads are clean & undamaged
► Correct sealing method has been followed
► Fittings have appropriate clearance
► Hose routing isn't placing unnecessary load on the connection
► Complete assembly suits its operating conditions

Pressurised equipment should be isolated, assembled, inspected & recommissioned according to the applicable system & workplace procedures.