304 Seamless stainless steel pipe, 304 / 304L Stainless steel

What is 304 seamless stainless steel pipe?

304 Seamless stainless steel pipe refers to seamless pipe made of stainless steel 304 material. It is a stainless steel material with excellent corrosion resistance and high strength. "Seamless" refers to its seamless production process. Seamless stainless steel pipes are resistant to corrosion by weakly corrosive media such as air, steam, and water, as well as chemically corrosive media such as acids, alkali, and salts. They are also called stainless acid-resistant steel pipes.

The corrosion resistance of seamless stainless steel pipes depends on the alloy elements contained in the steel. Chromium is the basic element that makes stainless steel corrosion resistant. When the chromium content in steel reaches about 12%, chromium interacts with the oxygen in the corrosive medium to form a thin oxide film (self-passivation film) on the surface of the steel. , which can prevent further corrosion of the steel matrix. In addition to chromium, commonly used alloy elements for stainless steel seamless pipes include nickel, molybdenum, titanium, niobium, copper, nitrogen, etc. to meet the requirements for the structure and performance of stainless steel for various purposes.

304 stainless steel material:

304 stainless steel is a brand of stainless steel produced in accordance with American ASTM standards (ASTM A312). It is a general-purpose stainless steel material with stronger anti-rust performance than 200 series stainless steel materials. It is also relatively good in terms of high temperature resistance and can reach temperatures as high as 1000℃-1200℃.

304 stainless steel has excellent stainless corrosion resistance and good intergranular corrosion resistance. For oxidizing acids, it was found in experiments that 304 stainless steel has strong corrosion resistance in nitric acid below the boiling temperature with a concentration of ≤65%. It also has good corrosion resistance to alkali solutions and most organic and inorganic acids.

304 Stainless steel pipe specification:

Specifications	ASTM A 312 ASME SA 312 / ASTM A 358 ASME SA 358
Dimensions	ASTM, ASME and API
SS 304 Pipes	1/8″ NB – 16″ NB
ERW 304 Pipes	1/8″ NB – 24″ NB
EFW 304 Pipes	6″ NB – 100″ NB
Size	1/8″NB TO 30″NB IN
Specialized in	Large Diameter Size
Schedule	SCH20, SCH30, SCH40, STD, XS, SCH60, SCH80, SCH120, SCH140, SCH160, XXS
Type	Seamless / ERW / Welded / Fabricated / LSAW Pipe
Form	Round, Square, Rectangular, Hydraulic Etc
Length	Single Random, Double Random & Cut Length.
End	Plain End, Beveled End, Treaded

Chemical composition of 304 stainless steel:

The chemical composition of 304 stainless steel mainly includes carbon (‌C)‌, ‌silicon (‌Si)‌, ‌manganese (‌Mn)‌, ‌chromium (‌Cr)‌, ‌nickel (‌Ni)‌, ‌sulfur (‌S)‌, ‌phosphorus (‌P)‌ and nitrogen (‌N)‌, the contents of chromium and nickel have a decisive influence on the performance of 304 stainless steel. ‌304 contains 18% chromium and 8% nickel. 304 is equivalent to China's 0Cr19Ni9 (0Cr18Ni9) stainless steel.

C：≤0.08 

Si ：≤1.0  

Mn：≤2.0 

Cr：18.0～20.0 

Ni ：8.0～10.5

S ：≤0.03 

P ：≤0.045 

N≤0.1。

304 stainless steel vs 304L stainless steel

Both 304 stainless steel and 304L stainless steel are austenitic stainless steel, and the corrosion resistance of austenitic stainless steel comes from the chromium oxide protective layer formed on the surface of the stainless steel. The most basic difference between them is the chemical composition. "L" stands for low carbon. The carbon content of 304L stainless steel is less than 0.03; the carbon content of 304 is less than 0.08. The biggest feature of 304L stainless steel is its increased sensitivity to intergranular corrosion. The carbon content of the welded area is reduced without causing actual thermal sensitization problems. In terms of price, the price of 304L stainless steel is higher than that of 304 stainless steel. If 304L is used instead of 304, the cost will increase.

304 seamless stainless steel pipe production process:
304 seamless stainless steel pipes are made from steel ingots or solid tube blanks that are perforated into capillary tubes, and then hot rolled, cold rolled or cold drawn. The production process mainly includes smelting, rolling, piercing, straightening, cutting and other links. Each link has its specific requirements and operating specifications. Only by strictly following the requirements can high-quality 304 stainless steel seamless pipes be produced.

The main advantages and characteristics of 304 seamless stainless steel pipe are as follows:

1. High corrosion resistance
304 stainless steel contains 18% chromium and 8% nickel, which can effectively resist corrosion from most acids and alkalis, including sulfuric acid, nitric acid, hydrochloric acid, etc. It has good corrosion resistance in harsh environments such as acid rain. ‌This property makes it widely used in several industrial fields such as food processing, ‌pharmaceuticals and chemicals. ‌

2. Good mechanical properties
‌304 seamless stainless steel pipe has high strength and toughness and is not easy to deform or break. ‌This excellent mechanical property makes it perform well in environments that need to withstand heavy pressure or vibration. 304 seamless stainless steel pipe has excellent strength and toughness at room temperature. The tensile strength is as high as 520MPa and the yield strength is as high as 205MPa.

3. Easy to process and weld
304 seamless stainless steel pipe has good plasticity and weldability, is easy to cut, bend and weld, and can be adjusted in shape, thickness and size through cold working and hot working, saving a lot of time and cost. ‌At the same time,‌its welding quality is high,‌which can ensure the sealing and reliability of the pipeline system. ‌

4. Heat resistance
304 seamless stainless steel pipe has good heat resistance under high temperature conditions. It can work below 800℃ for a long time and is not prone to oxidation and embrittlement.

5. Smooth surface
The surface of 304 seamless stainless steel pipe has been polished, is not easy to rust, has good gloss, and has a good decorative effect. Commonly used in the manufacture of equipment and components that require an aesthetically pleasing surface.

6. Long life
‌Due to the excellent corrosion resistance and mechanical properties of 304 seamless stainless steel pipes, ‌its long service life and ‌low maintenance costs,‌save enterprises a lot of money and time costs,‌while ensuring the long-term stable operation of the pipeline system . ‌

7. Wide application areas
304 seamless stainless steel pipes are widely used in the oil and gas industry, chemical and pharmaceutical industry, construction and decoration industry, machinery manufacturing industry, and food and beverage industry. Common applications include pressure vessels, transmission pipelines, petroleum pipelines, chemical equipment, etc.

‌For example,‌in the oil and gas industry,‌it is widely used in the manufacturing of oil and gas pipelines;‌in the chemical and pharmaceutical industry,‌it is used in the manufacturing of various chemical reaction devices and transmission pipelines;‌in the construction and decoration industry ,‌It is used in the manufacture of various pipes and decorative parts;‌In the machinery manufacturing industry, 304 precision stainless steel is used to manufacture bearings,‌gears,‌springs, valves,‌tools,‌knives, etc.;‌In the food and beverage industry ‌It is used for the transportation of liquid food.

In summary, ‌304 stainless steel seamless pipe has become one of the commonly used stainless steel pipes in the industrial field due to its high corrosion resistance, good mechanical properties, good processability, heat resistance, beautiful appearance, long life and wide application. 

Applications of 304 seamless stainless steel pipe:

304 seamless stainless steel pipe has a wide range of uses, mainly including the following aspects:

1. Food processing equipment
Since 304 stainless steel has good corrosion resistance and oxidation resistance, it can remain stable in environments exposed to moisture, acid, alkali, salt and other substances, will not produce harmful substances, and meets food hygiene requirements. Therefore, 304 stainless steel is often used to make food processing equipment, such as canning machines, fermentation tanks, candy machines, beverage machines, etc.

2. Kitchen utensils
Since 304 stainless steel has good corrosion resistance and oxidation resistance, it can remain stable in environments exposed to moisture, grease, acid and alkali and other substances, without producing harmful substances, and meets food hygiene requirements. Therefore, 304 stainless steel is often used to make kitchen utensils, such as sinks, faucets, knives, pots, etc.

3. Medical equipment
Since 304 stainless steel has good corrosion resistance and oxidation resistance, it can remain stable in environments where it comes into contact with blood, medicinal solutions, disinfectants and other substances, without producing harmful substances, and meets medical and health requirements. Therefore, 304 stainless steel is often used to make medical instruments, such as scalpels, syringes, infusion sets, dental instruments, etc.

4. Chemical equipment
Because 304 stainless steel has good corrosion resistance and oxidation resistance, it can remain stable in environments exposed to various organic acids, inorganic acids, alkalis and other substances, without producing harmful substances, and meets chemical industry safety requirements. Therefore, 304 stainless steel is often used to make chemical equipment, such as reactors, heat exchangers, storage tanks, pipelines, etc.

5. Building decoration materials
Since 304 stainless steel has good surface finish and aesthetics, it can form surface effects of various colors and textures, which meets the requirements of architectural aesthetics. Therefore, 304 stainless steel is often used to make building decoration materials, such as curtain walls, railings, doors and windows, etc.

Read more: Carbon steel vs Stainless steel or Seamless vs Welded pipe