Industrial stainless steel piping and processing equipment
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Why stainless steel?
Stainless steel is a steel and so it is typically very strong. This gives it great pressure and temperature resistance. It is also a tougher, more durable metal than cast iron, ductile iron, brass or copper.
Stainless steel materials get their designation from the fact that they are very corrosion resistant. This plus their toughness and strength make stainless steels a useful material option for compact miniature flow control valves. This is despite being more difficult to shape and therefore more expensive.
Download this page as a PDFWhy metal valves if plastic ones are usually more corrosion resistant and more economical?
It’s true, plastic valves are more corrosion resistant than metal valves in most applications. But, metal valves are more durable and can resist both higher pressures and higher temperatures better than plastic valves.
Get more information about choosing between plastic, brass and stainless steel for valve bodies in our blog post: Miniature Ball Valves: Plastic, Brass or Stainless Steel?
The basic rules of thumb for stainless steel chemical resistance:
Resistance to organics and organic solvents varies among stainless steels and depends on the chemical, its concentration and the stainless steel alloy or recipe.
Some examples of why you need to know more about stainless steels used in miniature and compact flow control valves.
BVSS series two-way ball valve
BVSS Series - 2 Way Stainless Steel Ball Valves
These full port and standard port ball valves have a great working temperature and pressure range. The body of the valves are CF8M stainless steel, but internal and external components are made of both CF8M and 304 stainless steels.
CSP Series - psi Check Valve – Poppet
These poppet check valves have a good working temperature and a great operating pressure range. The body and most of the components of these valves are 316 stainless steel but the retaining ring is 15-7 stainless steel.
CSP series poppet check valve
316 stainless steel body, poppet retainer and spring
15-7 stainless steel retaining ring
What’s CF8M stainless steel? Why use both CF8M and 304 stainless steel in the same valve? Are CF8M and 304 equally corrosion resistant? What’s 15-7 stainless steel? If 316 stainless steel is so corrosion resistant, why use one part made of 15-7 when all the other metal used in the valve is 316?
Read on to find the answers to these and other questions plus useful information and FAQs about the stainless steels most commonly used to make compact and miniature flow control valves.
More about steel and some of the whys of stainless steels
What’s the difference between iron and steel?
Iron is a metal, an element, and it is pretty reactive. That is, it oxidizes or rusts easily. But steel is an iron-carbon alloy. It is much stronger than iron while still being fairly easy to work with and shape.
The amount of carbon in steel is the most important factor in determining its strength. The ratio of iron to carbon also affects a steel’s ductility or workability. More carbon is stronger but harder to work while less carbon is easier to work but not so strong.
Five axis machining.
What is ductility and workability and why does this matter?
Metal ductility is the ability of a metal to be shaped and stretched without breaking. Brittleness is the opposite of ductility. Typical metal working processes include roll forming, bending, cutting with a guillotine shear, drilling and stamping.
The workability of a metal is how easily it can be shaped without cracking when it is subjected to different metal working processes. If a metal has high ductility it is easier to work. Workability varies with the shaping process used and the metal’s physical characteristics.
There are over 250 different stainless steel alloys
Steel is an alloy of iron and carbon. It also includes one or more additional elements, usually metals. These added ingredients give different steel types their particular chemical and physical properties such as corrosion resistance, strength, workability and so on.
Stainless steels get their name from the fact that they are very corrosion resistant. This corrosion resistance is provided by adding chromium. Other ingredients (elements) are added to stainless steels to balance the increased corrosion resistance with desirable physical traits.
Chromium gives a stainless steel its special advantage
Stainless steels generally contain at least 10.5% or more chromium by weight. But chromium content can range up to 30%. It provides stainless steel with its passivity, another way of saying its corrosion resistance.
What is meant by metal passivity?
Metal passivity is when an oxide film forms on the metal’s surface. This film prevents any additional chemical corrosion of the metal. Adding chromium to stainless steels forms an extremely thin but uniform, continuous, tenacious and stable chromium-rich oxide film on the surface of the steel.
The most important differences between different stainless steel types are their workability relative to their corrosion resistance. It is important to remember that the more workable a metal is, the easier it is to form into useful shapes. A stainless steel that is easier to shape means cheaper parts.
Key elements added to stainless steel alloys or formulations that provide corrosion resistance
There is more detail about what how these added metals influence the characteristics of a stainless steel type further along in this post.
Some general information about stainless steel types
There are five families of stainless steel (see below) and every one of them gets most of their corrosion resistance from the chromium component of the alloy.
Why stainless steel metal valves if they are more expensive?
Corrosion resistance
Stainless steel chemical resistance to acids
As a rule of thumb, stainless steels tend to be resistant to acidic corrosion. This is not a hard and fast rule though. Exact resistance levels vary by the type of stainless steel, the concentration of the acid, the type of acid and its temperature. If there are mixtures of chemicals or their concentrations vary, testing is probably a good idea. In general, best practice is to obtain part samples and test them in real operating environments.
Stainless steel chemical resistance to bases
Stainless steels generally have a strong resistance to corrosion from weak bases, even in high concentrations and in high-temperature environments. Strong bases can cause cracking or etching. Be especially careful with chloride solutions such as sodium hypochlorite.
Stainless steel chemical resistance to organics, organic solvents and organic chemicals in general
The resistance of stainless steels to different organic chemicals varies by the chemical, its concentration and the chemistry of the steel alloy. In general, 300-series stainless steels are the best stainless steels at resisting corrosion from organics. Environmental conditions such as temperature and the availability of free oxygen have significant effects on a stainless steel’s corrosion resistance to organics.
There are five stainless steel types or families
What are the key elements added to iron to make stainless steel alloys?
Chromium as a steel alloying element
As mentioned earlier, chromium is an alloying element added to steel to increase its resistance to oxidation. Chromium is the key ingredient in stainless steel formulas that makes them “stainless”.
Nickel chunk.
Nickel as a steel alloying element
Nickel is added to stainless steels to increase their strength, ductility and toughness. It is the addition of nickel to stainless steel that makes it non-magnetic. It also improves any stainless steel’s resistance to strong acids.
Nitrogen as a steel alloying element
Nitrogen increases a stainless steel’s resistance to pitting corrosion and corrosion between the grains or small crystals that make up the metal. In austenitic stainless steels, nitrogen increases the yield strength. Yield strength is the amount of force required to permanently distort or deform the metal.
Molybdenum as a steel alloying element
Molybdenum is added to stainless steels to increase corrosion resistance. It is especially effective at preventing pitting and crevice corrosion from environments where chlorides are found such as exposure to sea water or deicing salts. It also improves corrosion resistance to sulfuric, phosphoric and hydrochloric acids. An added benefit is that it improves the mechanical properties of stainless steels at high temperatures.
Manganese is also used in some stainless steel alloys
Manganese improves a stainless steel’s hot working properties and increases its strength, toughness and hardenability.
What is austenitic stainless steel?
Austenitic stainless steels are the most widely used corrosion resistant steel alloys. They are typically what is meant when the generic term "stainless steel" is used. These alloys provide toughness and corrosion resistance even at very low temperatures. Austenite stainless steels give up some ease of shaping in exchange for gaining greater durability and corrosion resistance. They generally cannot be hardened by heat treatment but work-hardening will make them stronger.
What is work hardening?
Metal is work hardened by changing its shape without the use of heat. This process is also known as plastic deformation. Forging is a common work hardening process.
Austenitic stainless steels are widely used to make valves and valve components
Austenitic stainless steels are the most widely used stainless steels for manufacturing valves. Austenitic steels are particularly useful because they are tough while remaining fairly ductile. A ductile metal is one that can be formed and worked without breaking.
Why are austenitic stainless steels so popular for making miniature valves?
All austenitic stainless steels have very good corrosion resistance, strength and toughness.
Austenitic stainless steels are very corrosion resistant
Austenitic steels are the most corrosion resistant family of stainless steels.
Austenitic steels are the most corrosion resistant family of stainless steels. This added corrosion resistance is provided by the addition of molybdenum and copper. Molybdenum helps prevent pitting and crevice corrosion, especially where there is exposure to chlorides and sulfur. Copper provides greater corrosion resistance to sea water and sulfuric acid. Nitrogen also increases its overall corrosion resistance.
Austenitic steels are strong and durable
The austenitic family of stainless steel alloys have impressive mechanical properties. These include excellent strength and toughness. Austenitic stainless steels also maintain these mechanical properties in conditions ranging from sub-zero to elevated temperatures.
Austenitic steels have broad operating temperature ranges
Austenitic steels have excellent toughness, particularly at low sub-zero or cryogenic temperatures. Miniature valves made of austenitic stainless steels have very good normal operating temperature ranges that frequently ranging from well below zero up to 400°F (about 200°C).
Typical austenitic stainless steels used in valves
These are the most common austenitic stainless steel types or alloys used to make compact and miniature flow control valves and valve components:
Typical valve components made of stainless steel
About 303 stainless steel
This is the most machinable stainless steel in the austenitic family of stainless steels. The addition of sulfur provides the improved machinability. Unfortunately, this also reduces its corrosion resistance and slightly reduces its toughness. But, the corrosion resistance of 303 stainless steel is still good in mild environments. Its toughness also remains excellent, typical of all the austenitic stainless steels. 303 type stainless steel is typically used for stainless steel parts that require a lot of machining.
Get a copy of the ISM 303 Stainless Steel Chemical Compatibility guide.
About 304 stainless steel
This is the most versatile and the most widely used stainless steel. It has excellent corrosion resistance when exposed to corrosive liquids and gases. It does suffer from pitting and crevice corrosion when exposed to chlorides such as sea water or de-icing salts. 304 stainless steel has good machinability but it is not quite as easy to shape as the 303 type.
Get a copy of the ISM 304 Stainless Steel Chemical Compatibility guide.
303 vs 304 stainless steel
The 303 and 304 stainless steel alloys have very similar mixes of metal elements. 303 stainless steel is frequently called the free-machining grade of 304 stainless steel. This machinability comes from adding sulfur to its recipe. It is relatively easy to shape 303 using high-speed, automated machining techniques. The corrosion resistance of type 303 is lower than 304. 303 stainless steel it should not be used where it will be continuously exposed to salt water.
These check valve series are examples of stainless valves with bodies made of 303 stainless steel and internal assemblies or parts made of 304 stainless steel.
303 stainless steels make the small, intricate valve bodies easier and cheaper to shape using automated machining. 304 stainless steels provide additional corrosion protection for the internal working parts of the valves.
Using a 303 stainless steel makes small, intricate valve bodies easier and more economical to shape with high-speed automated machining. 304 stainless steels provide additional corrosion protection for the internal working parts of the valves.
About 316 stainless steel
316 stainless steel is in the austenitic family of stainless steels. Next to the 304 type, 316 stainless steel is the most commercially important stainless steel. 316 stainless steel has added molybdenum while 303 and 304 do not. Molybdenum together with nickel provide improved corrosion resistance, even in aggressive environments. The added molybdenum is especially useful for improving corrosion resistance to chlorides like sea water and de-icing salts.
Get a copy of the ISM 316 Stainless Steel Chemical Compatibility guide.
304 vs 316 stainless steel
304 contains 18% chromium and 8% nickel while 316 contains 16% chromium, 10% nickel and 2% molybdenum. 316 stainless steel is more corrosion resistant than the 304 type. 304 is also not quite as durable as 316 or 316L but it usually costs a little less.
A fairly typical high-quality stainless steel ball valve series using both 316 and 304 stainless steels:
BVSS Series - 2 Way Stainless Steel Ball Valves
316 stainless steel for the BVSS valve body and internal parts
These surfaces will be in contact with the gas or liquid (the media) flowing through the valve. 316 provides excellent corrosion resistance to aggressive gases and chemicals.
304 stainless steel for the BVSS external parts
These surfaces will not be in continuous contact with potentially aggressive chemicals. 303 parts are cheaper and easier to make and have good corrosion resistance.
Here is another fairly typical high-quality stainless steel ball valve series. This one uses 316 stainless steel for the body, ends and ball. It is offered in three different O-ring seal materials to provide the broadest range of chemical compatibility and corrosion resistance:
SSBV Series - 2 Way Stainless Steel Full Port Ball Valves
About 316L stainless steel
316L is the low-carbon version of 316 stainless steel. 316L is one of the best stainless steels for very high temperature, high corrosion applications. 316L is highly durable but it is also relatively easy to fabricate and shape. Like 316 stainless steel, the added molybdenum significantly increases its corrosion resistance.
Get a copy of the ISM 316L Stainless Steel Chemical Compatibility guide.
316 vs 316L stainless steel
The main difference between 316 and 316L stainless steel is the difference in carbon content. 316 stainless steel has a maximum carbon content of about 0.08%. 316L has a maximum carbon content of about 0.03%. 316L also has lower percentages of other elements such as sulfur, phosphorus and copper. The 316L stainless steel is more ductile than 316 when annealed. It is also significantly more corrosion resistant, especially after being welded.
About CF8M stainless steel
CF8M stainless steel is also called cast 316 stainless steel. It is slightly magnetic while 316 is nonmagnetic. CF8M is slightly magnetic because it is not entirely austenite with more iron in it, about 5 to 20 percent.
CF8M vs 316L stainless steel
CF8M is essentially a cast version of 316 stainless steel. 316 valves are shaped by forging. Like the differences between 316 and 316L stainless steel, the key difference between CF8M and 316L is a tradeoff between a slightly reduced corrosion resistance and the advantages of casting. It is cheaper and easier to cast stainless steel valve bodies with complex shapes.
About 15-7 stainless steel
15-7 stainless steels are semi-austenitic stainless steels. 15-7 stainless steel has used for its high strength and hardness plus its good corrosion resistance. It is fairly easily to shape when this is done correctly. This stainless steel is particularly useful for applications that require high strength at high temperatures. 15-7 stainless steel gets its name from its 15% chromium and 7% nickel content. 15-7 is also known as stainless steels grade 632.
What is semi-austenitic?
Semi-austenitic means that a stainless steel is hardened by a process called precipitation hardening. Precipitation hardened semi-austenitic stainless steels are very strong, tough and have good corrosion resistance. They are frequently used to make springs and retaining rings.
15-7 stainless steel vs 304 and 316 types
15-7 type stainless steel is much stronger with a much higher tensile strength than type 304 or 316 stainless steels. The tradeoff is that 15-7 is not quite as tough or durable.
What is precipitation hardening?
Precipitation hardening is also called age hardening or particle hardening. It is a complex process that produces some of the strongest stainless steels. It is called precipitation hardening because it adds particles or precipitates to the steel to increases its strength.
A simplified description of the precipitation hardening process
Precipitation hardening requires a high temperature. It also usually needs to be done in either a vacuum or in a space filled with a gas that keeps out oxygen and will not react with the metal. The process typically takes from one to four hours but sometimes longer. After the initial production of the precipitation hardened metal, there is also an aging process. Many times, this is cold aging where the metal is kept at temperatures below freezing for hours.
Needless to say, precipitation hardened stainless steels are more expensive than most other types of stainless steel.
What is heat treatment?
Heat treatment or heat treating are metalworking processes used to change the physical properties of a metal. Heat treatment processes include annealing, case hardening, precipitation strengthening, tempering, normalizing and quenching. The main benefits of heat treating a metal are improving a metal’s
Keep these key takeaways in mind when buying a stainless steel miniature valve
Corrosion resistant does not mean invulnerable
Greater corrosion resistance does not mean invulnerable. You need to know the environment the valve will be installed in and what chemicals will be flowing the stainless steel part.
Keep in mind that mixtures of chemicals mean you cannot completely rely on published chemical compatibility reference information. Use chemical corrosion guides to make the best choices of valve materials for your application, get samples of the parts and test them in real conditions.
Get more information about material chemical compatibility and corrosion resistance in our article: How to Choose an In-line Filter – Chemical Compatibility
Stainless steel performs well in heat but internal parts of a valve, especially sealing surfaces, may not have the same operating temperature range as the stainless steel parts. Stainless steel miniature valves are strong but they are still rated for specific temperature and pressure ranges. This is because elastomers and engineered plastics are frequently used for seals and sealing surfaces.
Stainless steel valves will be more expensive
Stainless steels are noticeably more expensive than brass and plastic. Part of the reason for this is because stainless steels are so tough. It takes more effort and special tooling to shape them. The results in stainless steel valves having significantly higher prices than brass and plastic valves.
Stainless steel comes in many variations because it is a blended alloy of various elements. It is something you see daily in your life because it plays a crucial role in many aspects of everyday life. From your kitchen sink to medical equipment and supply lines and from complex industrial machinery to automobile parts, it has versatile usage. They are commonly used in the valve and process industries.
Different types of Industrial-Grade Stainless Steel have distinct characteristics that make them unique from each other. Understanding the differences between them is very important to choosing the right one for the right application.
In this article, you will understand the differences between three key industrial grades of stainless steel: 304, 316, and duplex along with their casting equivalents.
The uniqueness of stainless steel over other industrial metals lies in its resistance to corrosion and staining both inside and outside. This characteristic is because of the addition of various other elements which create a passive layer to protect it from rust and wear.
Although all stainless steel can shine like a mirror when polished it’s not just about the shine that you see but also the resilience and resistance to factors that may impact it. That is why by understanding their unique properties, ASTM casting equivalents, and optimal applications, you can confidently choose the right stainless steel for your specific needs.
Stainless steel can be broadly categorized into austenitic, ferritic, martensitic, and duplex. Among these, austenitic grades like 304 and 316 are well-known for their excellent corrosion resistance, while duplex stainless steel combines the best of both austenitic and ferritic structures. Due to this, it offers superior strength and durability over others.
Casting codes are important because they help you to understand the specific properties of the casting-grade stainless steel. Each part of the code represents different aspects of the alloy composition. Let’s learn the details from the table below.
These casting codes provide crucial information for selecting the right material for specific applications, ensuring that the alloy has the appropriate properties such as corrosion resistance, strength, melting point, toughness and weldability.
The ASTM standards are essential to ensuring quality in stainless steel castings. These standards cover the details of chemical composition, mechanical properties, and other requirements for a particular product and its applications.
Wrought Grade
Casting Equivalent
ASTM Specification
304
CF8
A351, A743, A744
304L
CF3
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A351, A743, A744
316
CF8M
A351, A743, A744
316L
CF3M
A351, A743, A744
Duplex
CD3MN
A890 Grade 4A
Super Duplex
CE3MN
A890 Grade 5A
410
CA15
A217
17-4 PH
CB7Cu-1
A743, A744
That is the reason for the successful and long life of products once they are cast in compliance with ASTM standards. These standards are developed for this purpose so that you can ensure consistency, safety, and reliability in stainless steel components used in critical applications.
304 stainless steel (SS) is a widely used austenitic stainless steel. It is known for its versatility, durability, and cost-effectiveness. Most of the general-purpose products are manufactured using 304 Grade SS. Furthermore, it has fairly good corrosion resistance and ease of fabrication, making it suitable for various industrial products.
Grade 304 typically contains around 18-20% chromium and 8-10.5% nickel, which provides good resistance to rust and environmental wear, as well as excellent strength. This chemical composition ensures good weldability and formability, making it versatile.
If mechanical properties are considered, it has good tensile strength. Its high formability means you can easily shape it to meet specific requirements. Furthermore, its durability adds to its versatility.
The casting equivalent for Type 304 stainless steel is CF8 (ASTM A351/ A743/ A744 Grade CF8), which retains the essential properties of 304, including its corrosion resistance and mechanical performance.
Type 304L is a low-carbon version of 304, which offers significantly improved weldability due to its lower carbon content. The lower carbon content helps to reduce the risk of carbide precipitation during welding processes. The casting equivalent for 304L is CF3 (ASTM A351/A743/A744 Grade CF3).
Its good resistance to corrosion and ease of fabrication make it a staple in food processing, brewing, and dairy industries because of compliance with FDA regulations. Additionally, it is widely used for kitchen utensils, sinks, silverware and other food-contact surfaces. Its hygienic properties make it ideal for environments requiring cleanliness. It is also a popular choice for architectural projects due to its aesthetic appeal. It is used widely in the valve and fitting industry for instance we make some of our stainless steel solenoid valves out of this same 304 Stainless Steel.
316 stainless steel is superior to 304 when it comes to resisting chloride corrosion, making it the go-to material for applications where corrosion resistance is needed. We use 316 to cast many of our ball valves and even some butterfly valves, solenoid valves and fittings.
In addition to chromium and nickel, 316 stainless steel contains 2-3% of molybdenum (2-3%), which significantly enhances its corrosion resistance. The presence of molybdenum also contributes to the overall strength and durability.
316 stainless steel has superior resistance to pitting and crevice corrosion, especially in saltwater environments. Its robust passive oxide layer provides long-term protection against aggressive chemicals such as chlorine. That is why it is preferred in harsh applications.
The casting equivalent for Type 316 stainless steel is CF8M (ASTM A351/ A743 /A744 Grade CF8M.
Similar to 304/304L the type 316L is the low-carbon version of 316. And, in a similar way to 304L, it improves its weldability by reducing the risk of carbon precipitation. The casting equivalent for 316L is CF3M (ASTM A351/A743/A744 Grade CF3M).
316 or CF8M and CF3M are ideal for marine fittings, chemical processing, and pharmaceutical manufacturing, where chemical exposure is high.
Now let's talk about a misconception of the magnetic nature of stainless steel that most people confuse. The austenitic stainless steel (316) is not magnetic because of its nickel content. However stainless steel 304 may be slightly magnetic in areas that have been deformed, such as by bending. For easy understanding, you can think of it as having paramagnetic characteristics, meaning that small particles in the 304 type can be attracted to powerful magnetic separators.
Duplex stainless steel represents a hybrid of ferritic and austenitic microstructures. This hybridization provides superior mechanical strength, excellent resistance to stress corrosion cracking, and improved toughness. Its unique dual-phase structure combines the advantages of both 304 and 316 alloys.
Duplex stainless steels generally contain equal parts austenite and ferrite, which provide a balanced microstructure.
As far as casting equivalent is concerned for duplex stainless steel, such as for Duplex is CD3MN (ASTM A890 Grade 4A). CD3MN offers a combination of austenitic and ferritic phases.
Super duplex stainless steel, like , has enhanced corrosion resistance, particularly in aggressive environments containing chlorides. The mechanical properties of provide high strength and durability and the casting equivalent for is CE3MN (ASTM A890 Grade 5A).
Duplex stainless steel offers a high strength-to-weight ratio, making it ideal for structural applications where durability is key.
Duplex stainless steel is frequently used in the oil and gas industry, particularly in pipelines and processing systems due to its excellent strength and corrosion resistance. It is also popular in chemical processing for its ability to withstand harsh chemicals. Structural applications, such as bridges and pressure vessels, benefit from its durability. We cast our valve safety lockouts out of duplex stainless steel to achieve the strength and integrity needed for these high-stress applications.
410 or CA15 A217 steel is a martensitic stainless steel grade that falls under the ASTM A217 specification. CA15 is the designation used for cast forms that contain around 11.5-13.5% of chromium. It is commonly used for casting in applications requiring good mechanical properties with moderate corrosion resistance.
It is a precipitation-hardening martensitic stainless steel and falls under the ASTM A743 and A744 standards for cast materials. It has higher strength, hardness, and corrosion resistance.
The chemical composition of 17-4 PH typically includes significant amounts of chromium (15-17.5%), nickel (3-5%), and copper (3-5%), along with small additions of elements like niobium to enhance precipitation hardening.
Furthermore, it undergoes heat treatment processes to achieve its high mechanical properties, which increases its yield strengths to Mpa.
These characteristics make it suitable for aerospace, valves, gears, and marine applications. Additionally, it’s easy to fabricate and weld.
304 is the most economical option for general purposes, whereas 316 has better corrosion resistance. Duplex offers both strength and corrosion resistance however it has a higher cost.
Stainless Steel Grade
Common Applications
304
Kitchen equipment, brewing tanks, dairy processing, automotive components, architectural structures
304L
Food and beverage handling, welded structures requiring resistance to corrosion
316
Marine fittings, chemical processing, pharmaceutical equipment, offshore platforms
316L
Pharmaceutical manufacturing, dairy processing, brewing, high-temperature welded environments
Duplex
Oil and gas industry, chemical processing, structural components, heat exchangers
Super Duplex
Offshore oil rigs, chemical tanks, pressure vessels, heat exchangers, desalination plants
410
Pump shafts, valve parts, petrochemical applications
17-4 PH
Aerospace components, high-strength fittings, valves
Casting equivalents are essential because the casting process requires alloys with specific properties such as:
By adjusting the chemical composition slightly, casting equivalents achieve these properties while maintaining mechanical performance similar to their wrought counterparts.
Casting Equivalent
ASTM Standard
CF8
ASTM A351/A743/A744
Casting Equivalent
ASTM Standard
CF3
ASTM A351/A743/A744 Grade CF3
Casting Equivalent
ASTM Standard
CF8M
ASTM A351/A743/A744 Grade CF8M
Casting Equivalent
ASTM Standard
CF3M
ASTM A351/A743/A744 Grade CF3M
Casting Equivalent
ASTM Standard
CD3MN
ASTM A890 Grade 4A
Casting Equivalent
ASTM Standard
CE3MN
ASTM A890 Grade 5A
Casting Equivalent
ASTM Standard
CA15
ASTM A217 Grade CA15
Casting Equivalent
ASTM Standard
CB7Cu-1
ASTM A743/A744 Grade CB7Cu-1
Your choice of stainless steel grade should be guided by the specific requirements of your application, such as exposure to chemicals, strength requirements, and budget constraints. For instance, if you need stainless steel for a commercial kitchen, 304 is ideal. For coastal installations, 316 is worth the extra cost, and for structural supports, the duplex offers the best of both worlds.
What are the main differences between stainless steel 304 and 316?
316 contains molybdenum, which enhances its resistance to chlorides compared to 304. 316 Stainless steel will offer better corrosion resistance when compared to 304 Stainless steel however even 316 will still corrode somewhat over time.
What is duplex stainless steel, and where is it used?
Duplex is a hybrid steel that combines the strength of ferritic and austenitic steels, commonly used in structural and chemical applications. This is found in valves and fittings that are usually used in offshore oil rigs or applications where a very good corrosion resistance is needed.
How do ASTM standards apply to stainless steel castings?
ASTM standards ensure that stainless steel castings meet specific quality criteria for safety and performance.
Which stainless steel is best for corrosion resistance: 304, 316, or duplex?
316 is best for chloride environments, while duplex provides excellent all-around corrosion resistance.
What are the ASTM casting codes for stainless steel grades?
ASTM A351 CF8 for 304, ASTM A351 CF8M for 316, ASTM A351 CF3 for 304L, ASTM A351 CF3M for 316L, and ASTM A890 for duplex grades like CD3MN and CE3MN.
Choosing the right stainless steel isn’t just about picking the shiniest option, it’s about matching the material to your application. You need to understand the differences, and also consult the ASTM standards to informed choice that balances performance, durability, and cost-effectiveness.
Contact us to discuss your requirements of 304 and 304L Valve Balls. Our experienced sales team can help you identify the options that best suit your needs.