Description
Steel Fuel / Brake Pipe Union 1/2″ UNF x 20 Male for 5/16″ Pipe
Steel male pipe union with a 1/2″ x 20 UNF thread, for 5/16″ (7.9mm) fuel and brake pipe – fuel pumps, carburettors, filters and larger brake ports. Supplied by EMS Spares, Leicester – over 30 years in automotive components.
Specification
| Thread | 1/2″ x 20 UNF male |
|---|---|
| Pipe size | 5/16″ (7.9mm) |
| Type | Male union |
| Hex / spanner size | N/A |
| Overall length | N/A |
| Material / finish | Steel, plated finish |
| Interchange reference | HU24* (brass equivalent) |
| EMS part number | EMS-A24S |
* Reference numbers are for identification and cross-reference only. EMS Spares is an independent UK supplier and has no connection with the owners of these part numbers. All dimensions are approximate.
Buyer’s guide: steel brake and fuel pipe unions explained
Why steel?
Steel fittings are strong, hard-wearing and low cost, and match the original-equipment style on many fuel and brake lines. A plated finish helps resist corrosion. For a part that will never seize, see our brass or stainless steel versions.
What does a brake pipe union do?
A brake pipe union is the threaded nut that holds a flared brake pipe tight against a component or hose. The union itself does not seal; it clamps the flare on the end of the pipe against the seat of the mating part, and that metal-to-metal contact makes the seal. That is why the thread and the flare type must both match.
Step 1 – identify your thread (the most common mistake)
| Thread | Outside diameter (male part) | Threads | Typically found on |
|---|---|---|---|
| 3/8″ x 24 UNF | 9.5mm approx | 24 per inch | Most British classics: MG, Triumph, Mini, Land Rover Series, Jaguar, kit cars |
| 3/8″ x 20 BSF | 9.5mm approx | 20 per inch | Older British cars, often pre-1960s (Morris Minor, early MG, Austin) |
| 7/16″ x 20 UNF | 11.1mm approx | 20 per inch | Larger British ports, some master cylinders and 1/4″ pipe |
| 1/2″ x 20 UNF (this part) | 12.7mm approx | 20 per inch | Fuel lines, carburettors and larger brake ports (5/16″ or 1/4″ pipe) |
| M10 x 1mm | 10mm approx | 1mm pitch | Most European and Japanese cars, kit cars |
Tip: 3/8″ UNF and M10 x 1 look almost the same and will start to screw together, then bind. Never force a fitting. Measure the male thread and check the pitch with a thread gauge.
Step 2 – male or female?
- Male union: screws into a female port (this part)
- 1/4″ pipe version – see our EMS-A24BS.
Step 3 – pipe size and material
For 5/16″ (7.9mm) outside-diameter pipe – fuel lines and larger brake/clutch lines. Suits copper, copper-nickel (Kunifer) and steel pipe.
How to fit – good practice
- Slide the union onto the pipe the right way round before you make the flare.
- Make the flare with a proper flaring tool, matching the flare of your old pipe and the port it connects to.
- Start the union by hand for several turns – it should turn freely. If it binds, stop and check the thread.
- Tighten with a suitable split / flare nut spanner, not an open-ended spanner.
- Bleed the brakes, then check every joint for leaks with the pedal pressed hard.
Safety: brakes are a safety-critical system. If you are not confident, have the work done or checked by a qualified mechanic.
Pack sizes
Available as 5, 10 or 15 unions. Larger packs cost less per piece.
Delivery
Free UK delivery on every order (including Northern Ireland, Highlands & Islands). Same-day dispatch on orders placed before 10am.
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FAQ
Will this fit copper (Kunifer) pipe? Yes – any pipe of the stated size: copper-nickel, copper or steel.
Need help? Message us with your vehicle and the part you are connecting to and we will confirm the right fitting before you order.
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