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The 8 Best union tube nuts of 2023

Are you trying to find union tube nuts among various brands on the market but aren’t sure where to begin? To assist you in finding the right one, we’ve put together a list of the 7 best to help you pick the perfect one!

We investigated and evaluated a number of the top-selling union tube nuts on the market in order to create our list of the best. Making a decision among the many options available is never simple. There are an infinite number of models available, each with a distinct price. And as you’ll find out, the best options aren’t usually the ones you imagine! This comparison is rich and relevant because of the numerous factors that were employed. You will find products featured in this ranking not only based on their pricing but also on their features and other customers reviews. To write this review, we completed 13 hours of research and did 24 union tube nuts tests. You won’t need to pick products at random any more. If you’re unsure of what to look for, browse our list and consult the buying guide!

An overview of our top picks

Table of contents

The best union tube nuts you can buy today

SaleNo. 1
Frienda 12 Pieces 3/8 Inch-24 Threads Brake Line Fittings Assortment for 3/16 Inch Tube (4 Unions, 8 Nuts)
  • Fit for: the unions measures approx. 0.6 x 0.9 inch, the nut measures approx. 0.67 x 3/8 inch, fit for most common inverted flare or double flare sizes for 3/16 inch tube, for use with 3/16 inch steel, poly coated or copper brake lines; Please confirm the size of the details according to the picture before purchasing
  • Size and material: both the unions and nuts are metric 3/8-24 threads (regular 3/16 inch tube fitting size), all brake line fittings are made of quality brass to prevent rust and plated for corrosion resistance
  • You will get: 12 pieces brake line fittings in the package, include 4 pieces unions and 8 pieces nuts, you can share them with your family and friends, these tubes unions are good fittings
  • Inverted flare union: these unions are a nice option to join 2 (3/16 inch) brake lines together
  • Brake line fitting connect: the nut is called the fitting for 3/16 inch tube, these unions fittings have a hex size of 3/8 inch and the threads are 3/8 inch with a thread pitch of 24
No. 2
MuHize Brake Line Fittings - 18 Pieces 3/8' - 24 Threads Fittings Assortment for 3/16' Brake Line Tube (6 Unions, 12 Nuts)
  • PACKAGE INCLUDE - MuHize upgraded Brake Line Fittings Replacement (Pack of 15): ① 6 x 3/8-24 threads unions; ② 12 x 3/8-24 threads nuts. Note:Both the unions and nuts are 3/8-24 threads (regular 3/16 inch tube fitting size) . Please check before shopping!
  • HIGHER QUALITY - MuHize brake line fittings are made of durable brass with unique rust corrosion proofing technology.
  • INVERTED FLARE UNION- Any 2 (3/16 inch) brake lines can be easy to joined with Muhize unions. both the sizes for unions and nuts are both 3/8-24 threads, which is the regular fitting size for 3/16 inch tube.
  • WIDELY APPLICATION - MuHize 3/8' - 24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 3/16 inch brake lines tube.
  • PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line. 100% brand new & made from excellent materials, and good contact.
SaleNo. 3
MuHize 15 Pieces 7/16-24 Threads Brake Line Fittings Assortment for 1/4” Brake Line Tube (5 Unions, 10 Nuts)
364 Consomer Reviews
MuHize 15 Pieces 7/16-24 Threads Brake Line Fittings Assortment for 1/4” Brake Line Tube (5 Unions, 10 Nuts)
  • PACKAGE INCLUDE - MuHize upgraded Brake Line Fittings Replacement (Pack of 15): ① 5 x metric 7/16-24 threads unions; ② 10 x metric 7/16-24 threads nuts; Note:Both the unions and nuts is metric 7/16-24 threads (regular 1/4 inch tube fitting size). Please check before shopping!
  • INVERTED FLARE UNION- Any 2 (1/4 inch) brake lines can be easy to joined with Muhize unions. both the sizes for unions and nuts are both 7/16-24 threads, which is the regular fitting size for 1/4 inch tube.
  • HIGHER QUALITY - MuHize brake line fittings are made of durable brass with unique rust corrosion proofing technology.
  • WIDELY APPLICATION - MuHize 7/16-24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 1/4 inch brake lines tube.
  • PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line. 100% brand new & made from excellent materials, and good contact.
No. 4
Eastyard 15 Pieces 3/8 Inch-24 Threads Brake Fuel Line Fittings Assortment Brass Inverted Flare Brake Assortment for 3/16 Inch Tube Includes 5 Pieces Unions 10 Pieces Nuts
48 Consomer Reviews
Eastyard 15 Pieces 3/8 Inch-24 Threads Brake Fuel Line Fittings Assortment Brass Inverted Flare Brake Assortment for 3/16 Inch Tube Includes 5 Pieces Unions 10 Pieces Nuts
  • Brake Line Fittings: 10 pieces 3/8" Tube Nuts and 5 pieces 3/8” Unions. 15 pcs brake line fittings assortment for 3/16" Tube in total.
  • Size: Both the unions and nuts is metric 3/8 (regular 3/16 inch tube fitting size) with a thread pitch of 24.
  • Material: Made of high quality brass, ductile at high temperature and has low magnetic attraction, durable and sturdy to serve for long time.
  • Inverted flare union: These unions connected with the nuts of 3/16 inch tube fittings perfectly
  • Qulity Assurance: These tubes unions are good fittings to share with your family and friends. If you have any questions with the product, we can provide technical support.
No. 5
(2) 2" Spa Hot Tub Heater Split Nut Union amp O-Ring Gasket Pair Balboa Gecko (Actual Size 3 Inch)
  • 3 1/4" Outside Diameter
  • 2 1/4" Inside Diameter, Gasket Rib Size 2 1/2"
  • Fits Most 15" Spa Heater Unions
  • Kit of (2) Split Nuts & Gaskets
SaleNo. 6
Brake Line Fittings - MuHize 15 Pieces 3/8'-24 Threads Assortment Brake Fitting for 3/16 Inch Brake Line Tube (5 Unions, 10 Nuts)
  • PACKAGE INCLUDE - MuHize upgraded Brake Fittings Replacement (Pack of 15): ① 5 x 3/8-24 threads unions; ② 10 x 3/8-24 threads nuts. Note:Both the unions and nuts is 3/8-24 threads (regular 3/16 inch tube fitting size) . Please check before shopping!
  • INVERTED FLARE UNION- Any 2 (3/16 inch) brake lines can be easy to joined with Muhize unions. both the sizes for unions and nuts are both 3/8-24 threads, which is the regular brake fitting size for 3/16 inch tube.
  • HIGHER QUALITY - MuHize brake fittings are made of durable brass with unique rust corrosion proofing technology.
  • WIDELY APPLICATION - MuHize 3/8' - 24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 3/16 inch brake lines tube.
  • PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line. 100% brand new & made from excellent materials, and good contact.
No. 7
4LIFETIMELINES Fitting Assortment 3/16" Metric Tube Nut, Union, Adapter, 9 SKU
  • The Metric Fitting Assortment, 9 SKU (36 Fittings), contains nine most popular metric fittings (tube nuts, unions, and adapters) for use when working with braking systems of Japanese and European vehicles.
  • Fitting Assortments are designed for specialty and general repair shops. Each assortment contains a specific collection of fast moving fittings that should be kept on hand when working with automotive hydraulic braking systems.
  • Assortments are packaged in shatter-resistant, see-through plastic trays. Locator labels on the inside lid make locating, selecting, and re-filling quick and easy.
  • Works with steel, copper nickel, copper coated steel, PVF-coated, and stainless steel lines
  • Lifetime warranty included on all products purchased from 4Lifetime Lines
No. 8
158 Piece Brass Union Tube Nut Brake & Fuel Line Fitting Assortment Kit - 25 Types
  • Our 158 Piece Brake Line Fitting Assortment Contains 25 Types of our most Popular Tube Nut Sizes
  • Comes inside of a 24 Compartment Clear Plastic Hard Case for easy storage and access.
  • Made In USA
No. 9
JACO MANUFACTURING 15-6-4-P-PG Polypropylene, Plastic NUT and Gripper, 220PSI, REDUCING Union Connector, 3/8IN to 1/4IN Tube
  • 220PSI
  • 3/8IN TO 1/4IN TUBE
  • PLASTIC NUT AND GRIPPER
  • POLYPROPYLENE
  • REDUCING UNION CONNECTOR
No. 10
Anderson Metals 50062-06 50062 Brass Compression Tube Fitting, Union, 3/8' x 3/8' Tube OD
222 Consomer Reviews
Anderson Metals 50062-06 50062 Brass Compression Tube Fitting, Union, 3/8" x 3/8" Tube OD
  • Three piece construction - nut, sleeve and body with attached insert
  • Use with copper, brass, aluminum, or plastic tubing
  • Standard fittings use short nuts
  • Easy to disassemble no flaring tool required
  • Primary uses water, gasoline, oil and vacuum lines
  • These fittings contain lead and are not allowed by federal law to be installed for potable water use in the U.S.A. and its territories.
SaleNo. 11
Brake Line Fittings Assortment for 3/16' Tube,Pack of 15 (5 Long Nuts,5 Short Nuts,5 Unions) 3/8-24 Threads
137 Consomer Reviews
Brake Line Fittings Assortment for 3/16" Tube,Pack of 15 (5 Long Nuts,5 Short Nuts,5 Unions) 3/8-24 Threads
  • 【Size Specification】- Include 5-3/16" short tube nuts, 5-3/16" long tube nuts, 5-3/16" unions, both the unions and nuts are metric 3/8" - 24 threads.
  • 【Superior Material】- These fittings are made of high-strength steel, and the surface is coated with anti-corrosion.
  • 【SAE Standard】- For SAE inverted flares and double flare size on 3/16".
  • 【Precautions】- The union is made of pure copper and has high strength. Please pay attention to the size and specifications of the union to prevent damage from destructive forces.
  • 【Lifetime Warranty】- You can return or exchange the fittings at any time, if you have any questions, please contact us and you will have a satisfactory reply, we look forward to your suggestions.
No. 12
Upgrade Brake Line Fittings - MuHize 10 Pieces Car Unions 7/16-24 Threads Nuts Assortment(2023 New), for 1/4” Camper Brake Line Tube Fittings
119 Consomer Reviews
Upgrade Brake Line Fittings - MuHize 10 Pieces Car Unions 7/16-24 Threads Nuts Assortment(2023 New), for 1/4” Camper Brake Line Tube Fittings
  • PACKAGE INCLUDE - 10 x 7/16-24 threads unions. Note:The unions are 7/16-24 threads for regular 1/4 inch tube. Please check before purchasing!
  • HIGHER QUALITY - MuHize brake line fittings are made of durable brass with unique rust corrosion proofing technology.
  • INVERTED FLARE UNION- Any 2 (1/4 inch) brake lines can be easily joined with Muhize unions. The size of the unions are 7/16-24 threads, which is the regular fitting size for 1/4 inch tube.
  • WIDELY APPLICATION - MuHize 7/16-24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 1/4 inch brake lines tube.
  • PROFESSIONAL - MuHize focus on outstanding features and benefits of braking line fittings. 100% brand new & made from excellent materials, and good contact.
No. 13
LTWFITTING Brass 1/2" OD x 3/8" OD Flare Forged Reducing Swivel Nut Union Tube Fitting(Pack of 5)
  • Type: Flare forged SWIVEL Nut Union
  • Tube Size 1 :1/2" OD Tube size 2 :3/8" OD
  • Materies: BRASS, Net Weight: 69g/PC
  • Choosing products dimensions and quantities at column of size and colour seperately,price would be more favorable if choosing wholesale.
No. 14
Legines Brass Compression Tube Fitting, Union, 1/4' OD x 1/4' OD Coupler, Pack of 2
445 Consomer Reviews
Legines Brass Compression Tube Fitting, Union, 1/4" OD x 1/4" OD Coupler, Pack of 2
  • Three piece construction - nut, sleeve and body with attached insert Use with copper, brass, aluminum, or plastic tubing
  • Manufactured for low and medium pressure tubing connection work where excessive vibration or tube movement is not involved.
  • Use with copper,aluminum and thermoplastic tub-ing.Not recommended for steel tubing.
  • Not recommended for application using gas eous media.
  • Meets specifications and standards of ASA, ASME asn SAE.
No. 15
LTWFITTING Brass 1/2" OD Flare Forged Swivel Nut Union,Brass Flare Tube Fitting(Pack of 5)
  • Type: Flare forged SWIVEL Nut Union
  • Tube Size:1/2" OD
  • Materies: BRASS, Net Weight: 79.5g/PC
  • Choosing products dimensions and quantities at column of size and colour seperately,price would be more favorable if choosing wholesale.
No. 16
MAHLER GATES Brake Line Fittings for 3/16 inch Brake Line Tube, 3/8-24 Threads, 12 Pieces (4 Unions, 8 Nuts)
35 Consomer Reviews
MAHLER GATES Brake Line Fittings for 3/16 inch Brake Line Tube, 3/8-24 Threads, 12 Pieces (4 Unions, 8 Nuts)
  • Package Include: 4x 0.57inch unions and 8 x 0.47inch nuts, fit for 3/16 inches Tube. Please confirm the size of the details according to the picture before purchasing:)
  • Fitment: This brake line nuts for Inverted Flares on 3/16 inch Tube. Works with steel, copper nickel, copper coated steel, PVF-coated, and stainless steel lines.
  • High Quality & Durable: Made of durable brass with rust-proof and corrosion-proof technology. Long time to use!
  • Professional & Wide Application: Our Brake Line Fittings fits for 3/16 inch Brake Line Tube, and the threads are 3/8 inch with a thread pitch of 24.
  • Warranty: We provide satisfactory service to customers. If the product is damaged or missing parts, please feel free to contact us, we will do our best to solve it for you.
SaleNo. 17
LTWFITTING Brass 3/8" OD x 1/4" OD Flare Forged Reducing Swivel Nut Union Tube Fitting(Pack of 5)
  • Type: Flare forged SWIVEL Nut Union
  • Tube Size 1 :3/8" OD Tube size 2 :1/4 " OD
  • Materies: BRASS, Net Weight: 43g/PC
  • Choosing products dimensions and quantities at column of size and colour seperately,price would be more favorable if choosing wholesale.
No. 18
New! 12 Pieces 7/16-24 Threads Brake Line Fittings Assortment for 1/4” Brake Line Tube (4 Unions, 8 Nuts)
  • ♛FEATURE: Any 2 (1/4 inch) brake lines can be easy to joined with this unions. both the sizes for unions and nuts are both 7/16-24 threads, which is the regular fitting size for 1/4 inch tube.
  • ♛WIDELY APPLICATION: 7/16-24 threads fittings commonly fits for regular inverted flare/ double flare sizes for 1/4 inch brake lines tube.
  • ♛WIDE USE: Fits for Most Hydraulic Braking Systems, Fuel Systems, and Transmission Systems,etc. It is also widely fit for household, industrial and commercial uses.
  • ♛HIGHER QUALITY: this brake line fittings are made of durable brass with unique rust corrosion proofing technology.
  • ♛NOTE: The pictures are accurate because of real shooting, please check it carefully to make sure it is what you need.
No. 19
A-Team Performance - 12 Piece 3/8 Inch-24 Threads Brake Line Fittings Assortment - for 3/16 Inch Tube (4 Unions, 8 Nuts)
  • 12 Piece 3/8 Inch-24 Threads Brake Line Fittings Assortment - for 3/16 Inch Tube (4 Unions, 8 Nuts)
  • These brake line fittings are made of durable brass to prevent rust and plated for corrosion resistance. Both the unions and nuts is metric 3/8-24 threads (regular 3/16 inch tube fitting size)
  • Intended for most common inverted flare/ double flare sizes for 3/16 inch tube, for use with 3/16 inch steel, poly coated or copper brake lines
  • Compatible with most common inverted flare/ double flare sizes for 3/16 inch tube
  • Package Inclusions - 12 piece brake line fittings in the package, include 4 pieces unions and 8 pieces nuts
No. 20
12PCS 3/8 Inch-24 Threads Brake Line Fittings Assortment for 3/16 Inch Tube, Brake Line Fittings Kit for Inverted Flare (4 Unions & 8 Nuts)
  • Package Include: Totally 12 pieces brake line fittings in the package, include 4 pieces unions & 8 pieces nuts.
  • Size: Both the unions and nuts is metric 3/8-24 threads (regular 3/16 inch tube fitting size).
  • Material: The brake line fittings are made of premium brass material, sturdy & rustproof. Plated for corrosion resistance, can service for a long life.
  • Application: The most common inverted flare/ double flare size fit for 3/16 inch tube, for using with 3/16 inch steel, poly coated or copper brake lines. Please check the size carefully before purchasing.
  • Satisfactory Service & Shipment -- 1 year warranty. Shipping from US. If you still have any questions , please feel free to contact us by e-mail. We will help you to solve problems within 24 hours.

How to choose a good union tube nuts

Does the idea of finding a fantastic union tube nuts make you anxious? When it comes to purchasing this product, specifically when deciding which model to select, has your head been spinning between options? You are not alone if that is the case. We are aware of the pressure involved in the purchasing process!

Your presence here indicates that you are interested in union tube nuts. Before choosing which product would be the best for your needs after being inundated with information, locate a reliable source with genuine selections. You can get that information from a variety of sources, including buying guides and rating websites, word-of-mouth recommendations from friends and family, online discussion forums where users can share their own experiences, product reviews that can be found all over the internet, and YouTube channels. You can only get the right product through exhaustive analysis. But you realize that’s not always simple. In order to ease your concerns, we have taken the time to develop a list of the top union tube nuts products available right now. You might be wondering how we came up with the list. How was this buying guide developed?

First, we used our algorithms to gather as much reliable data as we could about these products. To verify all the data gathered, we used both artificial intelligence and a lot of algorithms.
Then, our experts used criteria that are recognized in the business to evaluate them according to their quality to price ratio, allowing us to choose the top union tube nuts on the market right now!

The selection of the goods is not arbitrary. Before creating a list, we take into account a number of factors. Below are some of the criteria discussed:

Brand Value: What happens if you choose a dubious brand just because it appears to be a good deal? So the likelihood of receiving a product with a short shelf life increases. That is due to the fact that well-known brands have a reputation to uphold, while others do not. Top union tube nuts brands strive to provide some distinctive traits that set them apart from the competition. So, hopefully one or more of the items on our list will be perfect for you.

Features: Useful features are all you need, not tons of them. We consider the important aspects and select the top union tube nuts based on those.

Specifications: Numbers always help you measure the quality of a product in a quantitative way. We try to find products with higher specifications, but with the right balance.

Quality: A product’s quality may always be quantified with the aid of numbers. We look for goods with better standards that strike the proper balance. The best quality product that gets highly appreciated and recommended by experienced users.

Customer ratings:  Would it be accurate to suggest that the union tube nuts were used by hundreds of customers before you? Superior ratings indicate that many customers had better service.

Customer Reviews: Like ratings,  provide you with accurate and reliable information about the product from genuine customers. Customer ratings are very important to all of us because they contain accurate and reliable information about the customer service we received from several hundred customers.

Seller Rank: This is very intriguing! Not only do you need a good union tube nuts, you also need a product with rising sales that is trendy. It accomplishes two goals. First, the expanding user base proves the quality of the product. Second, given that number, producers must be able to offer greater quality and after-sales support.

Value: You get what you pay for, they say, so consider the value. Cheap isn’t always good and expensive isn’t always bad. However, that does not imply that spending a lot of money on a product that is flashy but underwhelming is a good idea. Before adding them to the list, we make an effort to evaluate how much value you can get for your money from your union tube nuts.

Durability: Durability and reliability are closely related concepts. You will benefit from a strong and long-lasting union tube nuts for months and years to come.

Product availability: Products come and go, and new ones replace the old ones. Most likely, a few new features and required changes were made. What use is it to use a supposedly good product if the maker no longer supports it? We make an effort to highlight products that are current and offered by one or more trustworthy sellers, if not more.

Negative Reviews: Yes, we do take that into account as well! The goods with the majority of bad reviews are filtered out and disregarded when we choose the best-rated one on the market.

These are the standards by which we selected our union tube nuts. Do we end our process there? Hell no. The most crucial fact about us that you should be aware of is that we regularly update our website with current and pertinent information. We have one more layer of filtration since we place the greatest importance on reader satisfaction. Please let us know if any product included here is incorrect, irrelevant, subpar, or simply out of date. We always value your opinions, and we’ll work hard to make any necessary corrections to our list in response to them.

Why should you believe us?

There are now thousands of possibilities for these products on Amazon, but choosing the best one can be difficult and time-consuming. And what union tube nuts should you purchase in 2022?

This guide is the result of more than 10 years of experience in researching, testing and writing about many topics. Each member of our team is an authority in their area. We read every article we could find online and every consumer review on every retail website for seven hours. Additionally, we discovered a ton of websites that offered helpful resources, including buying tips and thorough information on union tube nuts.