Important Features to Look for in Stainless Insert Fittings

By Paul Erb

There are some key features to look for when selecting stainless steel insert fittings for (PE) polyethylene pipe, that will ensure they install easily, last longer and hold more pressure. 

Stainless steel insert fittings are designed to make secure,  water tight connections to Polyethylene (PE) piping, which is used in an almost limitless range of indoor as well as outdoor applications, from water well and distribution lines, geothermal heating systems, ice skating rinks to maple sap collection to name just a few.

In this blog we are going to go over the following features and why they are beneficial. 

  • Uniform Wall Thickness 
  • High Quality Internal Surface Finish 
  • Easy Start Lead Barb 
  • Sharp Barb Profile  
  • Corrosion Resistant Material 

 1.Uniform Wall Thickness 

Many insert fittings on the market have serious inconsistencies in the wall thickness. This is typically caused by mold shifting during the sand-casting process. Mold shift, results in more material on one side leaving the other side with a thin, weaker wall. Insert fittings with thicker, consistent walls, are stronger and will last longer. 

The internal profile of an insert fitting is just as important as the outside. When selecting a Stainless Steel insert fitting, look for quality insert fittings made using the investment casting process or the swaged process. Both Investment casting and swagging processes provide accurate and uniform walls.  

PLUMBEEZE is committed to quality and ensures that insert fittings have a consistent wall thickness. 

Wall thickness and consistency cannot be determined by weight or appearance of the outside of the fitting, it may require close examination of the fittings cross section to detect inferior quality insert fittings. When selecting insert fittings there are 3 key problem areas to look out for. (see diagram below)  

#1 Fittings with a short thick wall section at each end. Some manufacturers purposely do this to cut raw material costs while giving the buyer the perception they are buying a quality heavy wall fitting.

Unfortunately, the cored section between the short thick sections at each end often has a very thin wall which can lead to structural failure and will reduce the longevity of the fitting. 


# 2
 A cored HEX increases turbulence, reducing the flow rates and pumping efficiency. In addition it weakens the fitting and can result in the fitting being deformed when tightened with pipe wrench.   

#3 Mold shift due to poor quality castings results in a thin wall section on one side, mold shift can result in catastrophic fitting failure especially in submersible pump applications where the fitting needs to support the weight of the pump column.  

 

2. Quality Internal Surface Finish 

Surface finish of the interior as with the consistent wall thickness point, is not evident at a glance and is often overlooked. Stainless insert fitting that are made by either the swage or investment casting process provide a smooth internal surface, reducing turbulence and friction loss as water flows through the fitting.

 

3. Easy Start Lead Barb 

The lead barb is the first barb that enters into the poly pipe. (This does not refer to the material lead). The lead barb has more taper to reduce the diameter at the end of the fitting, it is designed to be smaller than the inside pipe diameter to ensure an easstart when inserting into poly pipe, even if the pipe is cold and slightly oval in shape, due to being stored on a coil. 

 

In cold temperatures heating the poly pipe in hot water makes the poly pipe more pliable and easier to expand over the barbs during installation of the fitting, in warm or heated state poly pipe retracts and forms into the serrations for good sealing and pull-off resistance when secured by a quality All Stainless Steel Gear Clamp.  

When selecting an insert fitting look for the special lead barb feature, for faster and easier insertion into the pipe. The above diagram illustrates a tapered lead barb versus blunt start insert fitting. Save time and avoid frustrationdue to the challenges with installing blunt end fittings. 

 

4.  Sharp Barb Profile 

The function of the barbs or serrations is quite simple, they allow the poly pipe to easily slide onto the fitting but hard to remove. The degree of barb sharpness determines how well they grip when

a pulling force is applied. Sharp barbs make it practically impossible to pull the pipe off of the fitting, providing excellent blow 

off protection from system pressure as well as pull-off protection 


against 
pulling force such as the weight of a pump column in a submersible pump application. Additional pull-off resistance can be obtained by using an “extra-long insert fitting, which can have up to    13 barbs providing additional grip and space for double clamping.

 

5. Corrosion Resistant Material 

Stainless steel insert fittings for poly (PE) pipe have excellent corrosion resistance, which will extend the life of the fittings in your system. Unlike many brass alloysstainless steel does not contain zinc and is not affected by dezincification. 304 Stainless steel alloys are consistent from one supplier to the next and are suitable for a wide range of applications.  

 

In conclusion, some of these features are easier to identify visually than others. The selection of a fitting with all five of these key features ensures you have an excellent quality insert fitting that will install easily, last longer, prevent blow-off and hold up to high system pressures.  

 

Tags: Stainless Steel Fittings, How to, Insert Fittings

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