304 Stainless is a low carbon (0.08% max) version of basic 18-8 also known as 302.
ASTM A213 TP304 Stainless Steel Seamless Tube is manufactured by seamless process used in high pressure environment, stainless steel TP304 grade is the most used material due to its high strength and excellent corrosion resistance.
Type 304 has slightly lower strength than 302 due to its lower carbon content. Type 304 finds extensive use in welding applications because the low carbon permits some exposure in the carbide precipitation range of 800°F - 1500°F without the need for post-annealing operations.
However, the severity of corrosive environments may necessitate annealing after welding or the use of 304L.
Type 304L has a carbon content of 0.03% or less. This alloy can be used in the as-welded condition without becoming susceptible to intergranular corrosion.
304 stainless is a low-carbon (0.08% max) version of basic 18-8, also known as 302. Type 302 has 18% chromium and 8% nickel. Type 304 has a slightly lower strength than 302 due to its lower carbon content. Type 304 is used in welding applications, because the low carbon permits some exposure in the carbide precipitation range of 800° F - 1500° F without the need for post-annealing operations. However, the severity of the corrosive environments may necessitate annealing after welding or the use of 304L. Type 304L has a carbon content of 0.03% or less.
The main constituents of 304 stainless steel - other than iron - are Chromium and Nickel.
Type 302 stainless steel is characterized by its composition, which includes 18% chromium and 8% nickel. This specific alloying makes it highly resistant to oxidation and corrosion, while also providing good strength and formability. However, when it comes to type 304 stainless steel, the composition differs slightly. Type 304 is essentially a low-carbon version of type 302, with a maximum carbon content of 0.08%. This reduction in carbon content affects the steel’s overall properties, including its strength.
One of the key distinctions between type 302 and type 304 stainless steel is the strength. Due to its lower carbon content, type 304 generally has slightly lower strength compared to type 302. Despite this, type 304 offers significant advantages in certain applications, particularly in welding processes.
The reduced carbon content in type 304 stainless steel makes it particularly suitable for welding applications. In welding, exposure to high temperatures can lead to carbide precipitation, a process where chromium carbides form at the grain boundaries of the steel. This can compromise the material’s corrosion resistance. However, type 304’s low carbon content allows it to tolerate some exposure to the carbide precipitation range, which typically spans from 800° F to 1500° F. This tolerance reduces the need for post-annealing operations, making type 304 a practical choice for many welding tasks.
Nevertheless, the severity of the corrosive environments in which type 304 stainless steel is used may require additional measures to ensure long-term durability. In such cases, post-weld annealing might be necessary to restore the material’s corrosion resistance. Alternatively, type 304L, which has an even lower carbon content of 0.03% or less, may be used. The reduced carbon content in type 304L further minimizes the risk of carbide precipitation and enhances the material’s performance in welding applications.
304 stainless steel is a low-carbon variant of type 302, distinguished by its slightly reduced strength but superior performance in welding applications due to its lower carbon content. While type 304 is generally suitable for most applications, the choice between type 304 and type 304L should be based on specific requirements, including the corrosive nature of the environment and the need for post-weld processing. Understanding these differences helps in selecting the appropriate stainless steel grade for various industrial and construction applications.
In sanitary systems, stainless steel plays a critical role due to its non-reactive properties and ease of cleaning. These systems are designed to maintain high levels of hygiene and prevent contamination, which is essential in healthcare facilities, laboratories, and food and beverage industries. Stainless steel’s smooth surface prevents the buildup of bacteria and other pathogens, making it ideal for applications such as piping, tanks, and fixtures in environments where cleanliness is paramount. The material’s resistance to rust and staining further ensures the system’s longevity and reliability.
The dairy and food processing industries require materials that can handle aggressive cleaning agents and resist corrosion from various food products. Stainless steel is the material of choice for equipment and components used in these industries, including mixing tanks, pipelines, and processing equipment. Its non-porous surface ensures that there are no places for bacteria to hide, making it easier to maintain sanitary conditions. Additionally, stainless steel’s resistance to high temperatures and chemical cleaning agents makes it ideal for use in pasteurization and other processing steps that require stringent hygiene standards.
Heat exchangers and evaporators are essential components in many industrial processes, including chemical manufacturing, HVAC systems, and power generation. Stainless steel is favored in these applications due to its excellent thermal conductivity, resistance to high temperatures, and durability. Heat exchangers, which transfer heat between two or more fluids, benefit from stainless steel’s ability to withstand thermal cycling and pressure changes. Similarly, evaporators, which are used to concentrate solutions by removing water, rely on stainless steel’s resistance to corrosion and scaling, ensuring efficient and reliable operation.
Feedwater heaters are used in power plants and industrial facilities to preheat water before it enters the steam generation system. Stainless steel is commonly used in these heaters due to its resistance to high temperatures and pressure, as well as its ability to withstand corrosive environments. The material’s durability ensures that feedwater heaters maintain optimal performance over long periods, contributing to the overall efficiency and safety of the steam generation process.
304 contains 18 - 20% Chromium (Cr). Chromium is the essential chemical in all stainless steel and it is that which forms the thin passive layer that makes the metal "stainless"
304 also contains 8-10.5% Nickel (Ni). This is added to make the Austenitic structure more stable at normal temperatures.
The nickel also improves high-temperature oxidation resistance makes the steel resistant to stress corrosion cracking.
Where the steel is to be stretched formed a lower percentage (8%) of nickel should be selected. If the steel is to be deep drawn a higher percentage is better (9% or more).
In addition a number of other chemicals may be present but these are expressed as maximum permited levels with the exception of the increased quantity of carbon required in 304H - i.e. a minimum of .04% and a maximum of 0.10%
*Maximum carbon content of 0.04% acceptable for drawn tubes
There are hundreds of different grades of stainless steel on the market. Each of these unique formulations of stainless steel offer some degree of corrosion resistance above and beyond that of plain steel.
The existence of these stainless steel variants can cause some confusion—especially when the names & formulations of two stainless steel alloys are almost the same. This is the case with grade 304 and 304L stainless steel.
| Element | Percentage by Weight Maximum Unless Range is Specified | ||
| 304 | 304L | 304H | |
| Carbon | 0.08 | 0.030 | 0.04-0.10 |
| Manganese | 2.00 | 2.00 | 2.00 |
| Phosphorus | 0.045 | 0.045 | 0.045 |
| Sulfur | 0.030 | 0.030 | 0.030 |
| Silicon | 0.75 | 0.75 | 0.75 |
| Chromium | 18.00 20.00 |
18.00 20.00 |
18.00 20.00 |
| Nickel | 8.0 10.50 |
8.0 12.00 |
8.0 10.5 |
| Nitrogen | 0.10 | 0.10 | 0.10 |
These three alloys are remarkably similar—but there is one key difference. In grade 304 stainless, the maximum carbon content is set at 0.08%, whereas grade 304L stainless steel has a maximum carbon content of 0.03%. The “L” in 304L can be interpreted as meaning extra-low carbon.
This difference of 0.05% carbon content produces a slight, but marked, difference in the performances of the two alloys.
Grade 304L has a slight, but noticeable, reduction in key mechanical performance characteristics compared to the “standard” grade 304 stainless steel alloy.
| Grade | Tensile Strength Rm N/mm² |
Yield Strength Rp 0.2, N/mm² | Elongation (%) |
| 304 Annealed | 500-700 | 195 | 40 |
| 304L Annealed | 460-680 | 180 | 40 |
| Data | Metric | English |
| Density | 8 g/cc | 0.289 lb/in³ |
| Hardness, Brinell | 123 | 123 | Converted from Rockwell B hardness. |
| Hardness, Knoop | 138 | 138 | Converted from Rockwell B hardness. |
| Hardness, Rockwell B | 70 | 70 | |
| Hardness, Vickers | 129 | 129 | Converted from Rockwell B hardness. |
| Tensile Strength, Ultimate | 505 MPa | 73200 psi | |
| Tensile Strength, Yield | 215 MPa | 31200 psi | at 0.2% offset |
| Elongation at Break | 70 % | 70 % | in 50 mm |
| Modulus of Elasticity | 193 - 200 GPa | 28000 - 29000 ksi | |
| Poissons Ratio | 0.29 | 0.29 | |
| Charpy Impact | 325 J | 240 ft-lb | |
| Shear Modulus | 86 GPa | 12500 ksi |
| Electrical Resistivity | 7.2e-005 ohm-cm | 7.2e-005 ohm-cm | at 20°C (68°F); 1.16E-04 at 650°C (1200°F) |
| Magnetic Permeability | 1.008 | 1.008 | at RT |
Design Features - Stainless Steel 304/304L
Typical Applications - Stainless Steel 304/304L
Tensile Requirements - Stainless Steel 304/304L
Each alloy represents an excellent combination of corrosion resistance and fabricability. This combination of properties is the reason for the extensive use of these alloys which represent nearly one half of the total U.S. stainless steel production. The 18-8 stainless steels, principally Alloys 304, 304L, and 304H, are available in a wide range of product forms including sheet, strip, and plate. The alloys are covered by a variety of specifications and codes relating to, or regulating, construction or use of equipment manufactured from these alloys for specific conditions. Food and beverage, sanitary, cryogenic, and pressure-containing applications are examples.
Alloy 304 is the standard alloy since AOD technology has made lower carbon levels more easily attainable and economical. Alloy 304L is used for welded products which might be exposed to conditions which could cause intergranular corrosion in service.
Alloy 304H is a modification of Alloy 304 in which the carbon content is controlled to a range of 0.04-0.10 to provide improved high temperature strength to parts exposed to temperatures above 800°F.
For example, the ultimate tensile strength (UTS) of 304L is roughly 85 ksi (~586 MPa), less than the UTS of standard grade 304 stainless, which is 90 ksi (~620 MPa). The difference in yield strength is slightly greater, with 304 SS having a 0.2% yield strength of 42 ksi (~289 MPa) and 304L having a 0.2% yield strength of 35 ksi (~241 MPa).
This means that if you had two steel wire baskets and both baskets had the exact same design, wire thickness, and construction, the basket made from 304L would be structurally weaker than the standard 304 basket.
So, if 304L is weaker than standard 304 stainless steel, why would anyone want to use it?
The answer is that the 304L alloy’s lower carbon content helps minimize/eliminate carbide precipitation during the welding process. This allows 304L stainless steel to be used in the “as-welded” state, even in severe corrosive environments.
If you were to use standard 304 stainless in the same way, it would degrade much faster at the weld joints.
Basically, using 304L eliminates the need to anneal weld joints prior to using the completed metal form—saving time and effort.
In practice, both 304 and 304L can be used for many of the same applications. The differences are often minor enough that one isn’t considered massively more useful over the other. When stronger corrosion resistance is needed, other alloys, such as grade 316 stainless steel, are usually considered as an alternative.
ASTM A213 / ASME SA213 is a America specification for stainless steel boiler, super heater, heat exchanger tubes, executed by most world stainless steel seamless tubes mills and factories, minimum wall thickness required in A213 seamless tube, or average wall thickness as customers requirement, tight tolerance of outside and wall thickness stated as A213 standard or A1016
Cold rolling steel is a method that is used to provide a dense, dimensionally precise piece of steel. The most commonly used grade of stainless steel is 304. All stainless steels are a specific alloy mix.
Cold rolled steel, also called CRS, is a process used to finish steel. Hot rolled steel is steel that is still warm enough to be malleable and run through pressure rollers. After cleaning, when the steel has cooled and is no longer elastic, the steel is then put through power rollers and cold rolled. This produces a product that has a fine, smooth finish.
The most commonly used grade of stainless steel is 304. Another name for 304 is 18/8 because it is 18 percent chromium and 8 percent nickel. These additions make it resistant to corrosion.
The difference between CRS and 304 stainless steel is that CRS is a process and 304 is an alloy. Steel, hot or cold rolled, will rust and corrode. It is used in applications where that is not a consideration. Stainless steel is an alloy with chromium and nickel that prevents rust and corrosion. It is used where rust and corrosion will be a problem. It is possible to buy 304 cold rolled stainless steel.
Stainless Steel is a chromium-based alloy known for its incredible anti-rust properties. But along with this, Stainless Steel alloys are also used due to their incredible strength. Stainless Steel 304 has incredible strength and durability. Its strength is one of the most sought-after traits of grade 304 SS. Stainless Steel 304L Pipes and 304 Pipes are solid and retain their strength at extreme temperatures.
Stainless Steel 304, 304 L, and almost every grade of Stainless Steel is brilliant at repelling corrosion. As a result of this property, Stainless Steel grade 304 Pipes also have the property of repelling the growth and spread of microbes and dirt on the surface of the Pipes. Hence, it is often used in applications that have a primary need for sanitization and monitoring cleanliness. Additionally, Stainless Steel 304 Pipes are incredibly easy to maintain. They can be cleaned very easily. Hence, Stainless Steel 304 Pipes are used at hospitals, kitchens, food processing localities, etc., where cleanliness is a requisite.
AS its name suggests, Stainless Steel is a material that prohibits rusting and corrosion even in extreme temperature and weather conditions, including high-pressure areas. The chromium present in stainless Steel reacts with oxygen to create a chromium oxide film or layer that settles on the surface of the metal. This layer is what protects the Pipes from corroding. It is a self-reparatory layer that does not require maintenance or refurbishing.
But what sets grade 304 apart is the addition of molybdenum to the alloying composition making it an austenitic grade of stainless Steel. Austenitic Steel has enhanced corrosion resistance. Hence, for applications in extreme conditions, Stainless Steel 304 Pipes are an ideal choice.
Stainless Steel 304 Pipes are entirely recyclable. Once its utility purposes have been outlived or fulfilled, it can be recycled and re-forged. When stainless Steel is recycled, it does not lose any of its properties. All of its chemical, physical, and mechanical properties remain intact. About 70% of existing Stainless Steel artifacts are made out of recycled material.
Even though Stainless Steel 304 Pipes are lightweight, they are solid. They won’t succumb to external weights and pressure. Hence, it is said that it is one of the most durable materials. Stainless Steel 304 Pipes can withstand extreme temperatures as well as extreme pressures.
Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.
Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.
Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.
The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.
Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.
The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.
