PEX Why to Consider Stainless Pex Crimp Fittings

The debate between brass and plastic PEX fittings has been going on for years. With the pros and cons of brass and plastic, the introduction of Stainless Steel PEX fittings changes the conversation as Stainless solves many issues with traditional PEX crimp fittings.

In this blog we are going to investigate the typical views between brass and plastic and how Stainless PEX fittings stack up.

The History of PEX Fittings

As mentioned, the debate between brass versus plastic has been going on since the introduction of plastic. There are plumbing contractors who insist on one over the other, while another group would use each material based on application.

When talking about Brass, there are many people who continue to use it as their main material because of the confidence they have from a strength perspective. There is hesitance among some contractors who feel plastic fittings are weaker and will not use them.

Another concern that contractors have with using plastic PEX crimp fittings is they require a thicker wall than metal fittings to meet manufacturing codes. This results in a reduced inside diameter which restricts flow. Metal (Brass and stainless) crimp fittings are stronger allowing for thinner wall and larger flow passages. If you are using plastic crimp fittings throughout a whole house, this can cause significant flow restriction, see chart below.



That being said, there are some applications where plastic would out last brass. If you have poor water quality plastic is a superior choice, over time brass can corrode and leak in these situations. The problem has been complicated with the change to No-Lead Brass, not all low lead brasses are created equal. Due to the high zinc levels combined with very thin wall structure of brass PEX crimp fittings any amount of corrosion can be problematic. Dezincification associated with high zinc alloys increases the risk of fitting failure.

Hydronic heating systems are another area where some contractors have hesitancy using Plastic PEX fittings, due to high temperature fluid flowing through the fittings continually. The debate on plastic versus brass continues.


Consider stainless steel, find out why.

There is uncertainty about the use of plastic and brass materials, stainless PEX crimp fittings incorporate all the positive features of plastic and brass, with none of the negatives. They provide high strength, high corrosion resistance and large flow passages.


300 Series Austenitic Stainless steels are inert against nearly all heat transfer fluids due to the chromium (III) oxide passivation layer covering the surface. When deionized water is used in glycol antifreeze solutions in hydronic systems, stainless steel is considered to be appropriate for wetted surfaces.

Corrosion Resistance

As I mentioned above, one of the issues with Brass is corrosion resistance. Due to the affects that poor water quality has on brass, stainless steel is being adopted more in many plumbing applications.

The corrosive attack on brass fittings has become more of a problem with PEX systems. Traditionally plumbing piping systems were made entirely from copper pipe and fittings. While copper is susceptible to corrosion there are a few differences between copper and brass you need to keep in mind. Copper is much more corrosion resistant than brass because brass is an alloy made up of multiple materials, mainly Copper and Zinc. The presence of zinc in brass makes brass susceptible to dezincification. PEX fittings made from 304 stainless steel do not contain zinc.

Now that many plumbing systems are moving to plastic PEX piping, the corrosive attack is concentrated on the brass fittings which make up a small percentage of the surface area of the plumbing system. With systems totally made up of copper pipe and copper / brass fittings, the corrosion is evenly spread on a much larger surface area throughout the system. This is the reason the conversation around corrosion resistance is so important when talking about PEX systems. Stainless steel’s superior corrosion resistance will outperform brass, especially due to the very thin wall structure of metal PEX crimp fittings.

Flow Rate

Flow rate is also a very important consideration. The reason is because the fitting inserts inside the pipe, rather than sealing on the outside like copper piping systems. This inherently reduces the flow rate. As I mentioned above plastic PEX has a smaller inside diameter than brass and stainless which will further reduce flow.

This may seem insignificant with one fitting. However, when there are many fittings in a system this flow restriction becomes a factor resulting in a lack of pressure down the line. When multiple fixtures are in use this complicates matters more, resulting in poor pressure and flow. While Brass and Stainless PEX fittings have the same standard and ID, the shape of the fitting also comes into account.


The main contributor to reduced flow is a 90-degree elbow, which is the most commonly used fitting in a system. When the water hits an abrupt change in direction it creates a lot of turbulence, which causes friction loss and reduces flow. PLUMB eeze Stainless Steel PEX Elbows were designed with a sweep to significantly reduce these effects.


Strength is important to think about as well. The main reason for this is because of hydraulic shock (water hammer). This is when a shockwave is sent through a plumbing system when a valve is suddenly closed and water “hammers” back down a pipe which causes stress on the pipe and fittings. This is a huge reason why supporting the pipe and fittings properly is so important.

As you can see in the image below, Stainless is much stronger than Brass and Poly.

In conclusion, history has proven that both brass and plastic PEX fittings have their advantages and disadvantages. Stainless PEX fittings eliminate the need and cost for dual inventories, as they feature the best attributes of both brass and poly. The superior corrosion resistance, flow rates and strength of these fittings demonstrate their versatility and how they can be used in a wider range of applications.

Stainless steel PEX fittings are an excellent choice for your next system.