Interchanging and Intermixing Tube Fittings, Part 2

Posted by David Brown | 7/31/14 7:30 AM 0 Comments

Intermixing Tube Fittings

In a previous blog, I wrote about interchanging tube fittings.  In this blog, I will discuss a more controversial topic - intermixing tube fitting components. Intermixing stainless steel tube fittings means using the components (body, ferrules or nuts) from one manufacturer with the components from another manufacturing.

Some Issues

Most manufacturers discourage this practice.  Their logic is easy to understand.  While most tube fittings seal using the same basic principles, each tube fitting design is unique and each tube fitting components is specifically designed to work with the other components to achieve a seal can increase dramatically.  The more dissimilar the design; the more likely it is that they tube fitting will leak or fail.

In order to work as designed, the components from one manufacturer would have to be identical in geometry and function as the intermixing brand.  Even then, it would be advisable to conduct testing to ensure that the tube fitting combinations sealed properly. 

So why do companies intermix tube fittings.   The basic reasons are:

  • Many different tube fittings are available at their facilities.  OEM equipment, site built systems, contractor supplies and other sources might increase the number of tube fitting designs in a plant.  
  • Installers and maintenance people are not able to tell the difference between tube fitting designs.
  • Purchasing may change suppliers and, by extension, change their tube fitting supplier.  When maintence orders new fittings to repair a system, they order the current tube fitting carried by their supplier. The current tube fitting vendors carry only one tube fitting design and that design is not compatible original fitting.

Done incorrectly, intermixing can lead to leaks, productivity and quality problems.  At worst, it can lead to safety and environmental problems.

Possible Solutions

It seems that the solutions might be straight forward.2leakfreevertical

  • Maintenance and Purchasing Departments must recognize that they have a variety of tube fitting designs in their facilities and that it is nearly impossible to change this.
  • Purchasing should establish channels to obtain replacement components for each brand.  Establishing a mulit-line source for most or all of your tube fitting replacements will reduce handling and inventory costs and stocking issues.
  • Train maintenance and installers on the proper identification and replacement of tube fitting components.
  • Check to see the tube fitting components have been tested to intermix with the current component.


Intermixing tube fitting presents problems for maintenance and production. The best course of action is to address these situations inadvance by recognizing tube fittng brands and having a source that can supply components that are completely intermixable with the original brand.  

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As usual we invite your comments, questions and suggestions for this blog or ideas for future blogs.

Topics: Tubing, Tube Fittings