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Miller 166571 Coolant Barbed Fitting 3/8 Tbg 5/8-18 Female — main product image
Miller

Miller 166571 Coolant Barbed Fitting 3/8 Tbg 5/8-18 Female

Brass barbed coolant fitting with 3/8" tubing to 5/8-18 female thread for secure, leak-free connections.

$50.99*
✓ In Stock on Amazon.com
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*Price sourced from Amazon.com. Last updated:Jun 04, 2026.Price and availability are subject to change.

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Overview

The Miller 166571 is a brass barbed coolant fitting designed to connect 3/8" inside-diameter tubing to a 5/8-18 female threaded port. It serves as a replacement or maintenance part for coolant circulation systems commonly found in Miller welding equipment, where consistent coolant flow is critical for torch and machine longevity. The barbed end pushes into flexible tubing and grips it mechanically, while the female threaded end screws onto a matching male port on the equipment.

Brass was chosen for this fitting because of its natural resistance to the corrosion that coolant chemicals can cause over time. For installers, the fitting is compact enough to work in the confined spaces typical of welding machine interiors. While it is a Miller OEM part, the standard thread and tubing dimensions mean it can potentially serve in other industrial coolant applications where the sizing matches. Securing the barbed end with a hose clamp and applying thread sealant to the female connection are recommended practices for a fully reliable seal.

Key Features

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Specifications

Brand
Miller
Model
166571
Connector Type
Barbed Fitting
Tubing Size
3/8"
Thread Size
5/8-18 Female
Material
Brass

Pros & Cons

👍 Pros

  • Brass construction resists corrosion from coolant chemicals and provides long service life
  • Barbed design grips 3/8" tubing firmly to prevent leaks and blowoffs under pressure
  • Standard 5/8-18 female thread ensures compatibility with common coolant system ports
  • Compact size allows installation in tight spaces around welding equipment

👎 Cons

  • Barbed connections require hose clamps for maximum security, which are not included
  • Only available in the single 3/8" to 5/8-18 size, so different tubing sizes need a different fitting
  • No included O-ring or thread sealant, requiring separate sealing materials for a fully leak-proof joint
  • Limited product documentation makes it difficult to verify pressure ratings before purchase

Frequently Asked Questions

It is designed for 3/8" inside-diameter tubing, using a barbed end to grip the hose securely.
The female end uses a 5/8-18 thread, which is a standard size found on many welding and industrial coolant systems.
It is constructed from brass, which provides corrosion resistance and durability in coolant environments.
While it is a Miller part, the standard 3/8" barb and 5/8-18 female thread dimensions allow it to work with other systems that use the same sizing. Verify your equipment's specifications before ordering.

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