Stainless Steel fittings, nipples, clamps, and other products are gaining popularity in more conventional plumbing applications. This is due to the increased cost of other materials such as No-Lead Brass, as well as, Contractors seeing more value in the properties of stainless such as the increase corrosion-resistance.
It is important to know that there are a number of misconceptions in the industry about Stainless Steel Products. These are very important to address because they lead to poor education in the marketplace. In this blog, we will look into 3 of the common misconceptions so that you have a better understanding when these questions come up.
The 3 misconceptions that we are going to dive into, are:
- Real Stainless Steel is Magnetic
- Stainless Steel Fittings and Nipples are sealed the same as other materials
- All Stainless Steel Fittings are the same
Magnetism of Stainless Steel
This is one of the most common misconceptions that we hear in the market. You will hear people say things like:
"the best way to check if something is really Stainless, or a good quality Stainless, is to stick a magnet to it. If the magnet does not stick to it, you have Stainless product. If it does, the quality may not be good, or it could be another material all together."
There is allot of confusion on the topic because Austentic Stainless Steels are indeed non-magnetic in their pre-worked state. However, once the Stainless has been cold worked in the manufacturing processes, it will become magnetic, even though the quality and alloy specification has not changed.
To be clear, the degree of magnetism is not an indicator of the materials corrosion resistance. The "magnet" test will not give you a clear answer to the grade or quality of stainless for plumbing products. It is important to know that lower grade stainless steels such as 200 series will have lower magnetic attraction than a much more corrosion resistant 300 Series stainless steels. For example 301 Stainless steel is much more corrosion resistant, although it does become magnetic when cold worked.
So, the real answer is that a Stainless Fitting for example may have varied degrees of magnetic attraction. The truth is it really doesn't matter. What matters is the alloy composition of Stainless, particularly the percentage of Chromium which forms a oxide layer on the steels surface. This layer is also referred to as the passive layer. In 316 stainless the addition of molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments.
The real answer is that a Stainless Fitting for example may have varied degrees of magnetic attraction. The truth is it really doesn't matter.
The percentage of nickel is also important in high chromium stainless steel. Nickel increases strength, impact strength and toughness, while also improving resistance to oxidization and corrosion.
The only way to really make sure on the quality is with an alloy analyzer. This will tell us what the exact chemical make up and the quality and corrosion resistance of the alloy.
Stainless Steel Fittings and Nipples are Sealed the Same as other Materials
The biggest push back that I hear about Stainless is that it doesn't seal well, or it is hard to work with. The main reason that people experience this is due to the fact that they don't understand that sealing Stainless has to be done differently than brass, for example.
The reason that it needs to be sealed different is due to the hardness of the material. Using conventional PTFE tape doesn't work well because the Stainless threads will actually cut the tape. This can essentially fuse the fitting and pipe together, which makes it hard to get apart and there will not be a good seal.
Stainless should be sealed using a tape that has nickel in it. The nickel gives the tape increased strength and will not be cut when tightening.
It is also recommended that Stainless pipe dope is used with the tape. This will create a perfect seal, and you will also be able to get the threads apart if needed.
For more information on sealing Stainless, check out this blog.
Once you understand how to seal Stainless Steel Fitting and Nipples properly, working with it is actually pretty easy. With the right instructions and installation products, you can become an expert in no time!
All Stainless Steel Fittings are the Same
Stainless Steel is a widely used term. It is very important to understand that there are many types of stainless. The reason why you need to know about this is because the type of stainless used will come into play when determining the right type for a certain application.
The main types of stainless that you will see in the plumbing industry is 304 and 316 grade. These numbers refer to the chemical make up of each. The main difference between these two is corrosion resistance. 316 Stainless fittings are much more corrosive resistant, and therefore, are suitable for industry, commercial and other applications. 304 is more of a conventional stainless that would be used in more "everyday" plumbing. Compared to other materials like brass or galvanized, 304 is still much more corrosive resistant.
The next aspect to pay attention to is fitting thickness or pattern. There are about 5 different patterns that you may come across. These will deliver different pressure ratings. Obviously, the thicker the pattern, the greater pressure rating it will have.
This is one of the biggest issues I hear from people. There may be 15% price difference between 2 fittings, and usually this is due to either the pattern difference or the stainless type (304 vs. 316).
When comparing Stainless pricing, taking type of material and pattern into account is the only way to get accurate information.
All Stainless fittings are not the same. There are many different configurations and it is important to know about them. Doing a proper comparison hinges on knowing this information.
Conclusion
Stainless Steel Plumbing products are continuing to grow in popularity. Because it is still new in many markets, these misconceptions are still prevalent. It is important to arm people with this correct information so that they are able to make the right product recommendations and ensure success for your customers.
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Stainless steel is a commonly used material in applications ranging from medical instruments or chemical storage to transport or power generation because of its high corrosion resistance, hygiene, and strength. While there are more than 3,500 grades of steel, not all stainless steel grades are created equally.
With so many options, how can you ensure you’re selecting the appropriate grade for your specific needs?
1. Choose the Right Metal for Your Operating Environment
To determine which grade of steel will uphold best in a given environment, think about the conditions your final product will face. Extremely low pH, high stresses and high temperatures, and crevice corrosion negatively impact stainless steel performance. Steels in the austenitic T3XX series, like the common types 316 and 304 alloys, retain their strength, toughness, and corrosion-resistant properties over the broadest temperature range.
Corrosion resistance is the main reason for choosing austenitic stainless grades. Type 316, with its molybdenum addition, even resists chloride ions found in marine and chemical processing applications. With any steel grade, high-quality structural design is the best defense against corrosion.
2. Prioritize Strength, Ductility, and Toughness
Next, consider these three top mechanical qualities:
- Strength: The stress a metal can withstand before it fractures or deforms
- Ductility: The ability of a material to have its shape changed, such as being drawn out into a wire or thread, without losing strength or breaking
- Toughness: The metal’s ability to deform and absorb energy before fracture
Stainless steel contains 10–30% chromium as its alloying element, which is what helps it resist corrosion. The nickel addition in austenitic grades provides the highest toughness and ductility among stainless grades. Grades high in chromium, molybedenum, and nickel are the most resistant to corrosion.
Alloy content is not the only aspect to consider when choosing a grade of stainless steel; the material’s processing also affects the mechanical response. The duration of time steel is held at different temperatures as part of its cooling process, as well as the total speed at which it is cooled can affect its overall quality.
While the hardness of carbon steels can be increased by heat treatment, austenitic stainless is hardened by cold working operations like rolling, bending, swaging, or drawing at temperatures below the recrystallization temperature. Be aware that increased hardness by cold working operations decreases other properties like elongation and impact resistance.
3. Factor in Form and Process
Austenitic stainless steel is widely available in bar, wire, tube, pipe, sheet, and plate forms; Most products require additional forming or machining before they can be used for their specific application.
Stainless steel tubing, for instance, may need bending or coiling, re-drawing, machining, welding, or end forming. If your stainless steel will see machining processes like CNC machining, drilling, reaming, bevel cutting, chamfering, knurling, or threading, choose a machining rate that mitigates the risk of work hardening or select a “free-machining” grade containing sulfur.
When welding any stainless steel parts, embrittlement in the weld area is a top concern. Choose a lower carbon grade like 304, 304L, or 316L to reduce carbide formation.
4. Consider Your Customers’ Preferences
Many designers choose stainless steel for its aesthetic appearance, whether that appearance is a shiny, electropolished “bright” finish, a dull “pickled” finish, a matte surface polished to a specific RMS, or a light-absorbing black oxide coating. Austenitic stainless steel grades can take any of these finishes plus the common addition of passivation.
Customers may also need certification for application-specific specifications. For instance, ASTM A213 and A249 should be used for boiler, superheater, and heat-exchanger tubes, while ASTM A908 should be used for hard-drawn austenitic stainless steel industrial needle tubing. There are more than 12,000 ASTM standards, and each addresses a specification so customers know the technical standards tested for chemical composition, heat treatment or temper, and other physical and mechanical attributes.
5. Manage Material Cost and Availability
Although high-performing austenitic stainless steels are the most expensive stainless steels upfront, they are well worth the investment. Choosing a corrosion-resistant material well-suited to its application reduces maintenance, downtime, and replacement costs. Life-cycle costing methods can quantify current and future costs and create an “apples-to-apples“ comparison of different materials.
Selecting a Stainless Steel Supplier
At Eagle Stainless we can help you prioritize your material requirements and guide you toward choosing the perfect stainless steel grades for your application. With quality management certifications in place since 1998, our commitment to quality is evident at every step of the process and designed to help you make the best steel selection for your industrial application.