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A312 stainless pipe and 304L seamless pipe are two different types of pipes used in different applications. The key differences between them are in their composition, mechanical properties, uses, and cost.
The key difference between A312 stainless pipe and 304L seamless pipe is in the composition of each material. A312 stainless pipe is made from an austenitic stainless steel alloy, while 304L seamless pipe is made from an austenitic low carbon stainless steel. This difference in composition affects the properties of each material, particularly its corrosion resistance, mechanical strength, and weldability.
A312 stainless pipe is an austenitic stainless steel alloy, which means that it is made from a combination of iron, chromium, and nickel. The chromium content of A312 stainless pipe ranges from 16-18%, and the nickel content usually ranges from 8-10%. Because of its high chromium and nickel content, A312 stainless pipe has excellent corrosion resistance and is highly durable when exposed to a variety of corrosive environments. Additionally, A312 stainless pipe has good mechanical strength, making it suitable for applications that require high strength, such as in structural applications.
In terms of weldability, A312 stainless pipe is generally considered to be good. It can be welded using most common welding processes, such as GTAW (gas tungsten arc welding), GMAW (gas metal arc welding), and SMAW.
Composition:
A312 stainless pipe is made of a combination of chromium, nickel, and molybdenum. This material is known as an austenitic stainless steel and is both heat and corrosion resistant. It is strong, durable, and has excellent formability.
304L seamless pipe is made of an austenitic stainless steel that contains low levels of carbon. It is also known as an austenitic stainless steel because of its low carbon content. This material is resistant to corrosion and is both heat and corrosion resistant. It is strong, durable, and has excellent formability.
304 steel Chemical Composition:
|
Grade |
C |
Mn |
Si |
P |
S |
Cr |
Mo |
Ni |
N |
|
|
304 |
min.max. |
-0.08 |
-2.0 |
-0.75 |
-0.045 |
-0.03 |
18.0-20.0 |
– |
8.0–10.5 |
-0.10 |
|
304L |
min.max. |
-0.030 |
-2.0 |
-0.75 |
-0.045 |
-0.03 |
18.0-20.0 |
– |
8.0–12.0 |
-0.10 |
|
304H |
min.max. |
0.04-0.10 |
-2.0 |
-0.75 |
-0.045 |
-0.03 |
18.0-20.0 |
– |
8.0–10.5 |
– |
304 steel Mechanical Properties:
|
Grade |
Tensile Strength(MPa) min |
Yield Strength 0.2% Proof (MPa) min |
Elongation (% in 50mm) min |
Hardness |
|
|
Rockwell B (HR B) max |
Brinell (HB) max |
||||
|
304 |
515 |
205 |
40 |
92 |
201 |
|
304L |
485 |
170 |
40 |
92 |
201 |
|
304H |
515 |
205 |
40 |
92 |
201 |
|
304H also has a requirement for a grain size of ASTM No 7 or coarser. |
|||||
304 steel Grade specifications:for 304 grade stainless steel
|
Grade |
UNS No |
Old British |
Europen |
Swedish SS |
Japanese JIS |
||
|
BS |
En |
No |
Name |
||||
|
304 |
S30400 |
304S31 |
58E |
1.4301 |
X5CrNi18-10 |
2332 |
SUS 304 |
|
304L |
S30403 |
304S11 |
– |
1.4306 |
X2CrNi19-11 |
2352 |
SUS 304L |
|
304H |
S30409 |
304S51 |
– |
1.4948 |
X6CrNi18-11 |
– |
– |
|
These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted. |
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Size Range:
|
Production |
Outside Diameter |
Wall Thickness |
|
Seamless Pipe |
6.00mm to 830mm |
0.5mm to 48mm |
Mechanical Properties:
A312 stainless pipe has a higher tensile strength and yield strength than 304L seamless pipe. It is also more ductile and has a higher melting point. The higher tensile strength and yield strength of A312 stainless pipe allow it to be used in applications that require strength and durability.
304L seamless pipe has a lower tensile strength and yield strength than A312 stainless pipe.
304L stainless pipe and A312 seamless pipe are two types of stainless steel pipes used in various industrial applications. While they both offer excellent corrosion resistance and mechanical properties, they have some distinct differences that make them suitable for different applications.
304L stainless pipe is a low carbon variant of 304 stainless steel, which is one of the most commonly used stainless steel alloys. Its slightly lower carbon content provides improved weldability and better corrosion resistance than regular 304 stainless steel. 304L stainless pipe is often used for applications requiring superior corrosion resistance, such as chemical processing, food and beverage processing, and petrochemical processing. It is also used in marine environments, due to its resistance to saltwater corrosion.
A312 seamless pipe is a type of stainless steel pipe that is manufactured without a seam or weld. It has a smooth, cylindrical surface and is made from a single piece of solid steel.The lack of a weld or seam makes A312 seamless pipes easier to clean and maintain, and they also offer greater resistance to corrosion and pressure than welded pipes.
A312 Stainless Steel Composition Chart
| Ni | 9 – 12 |
| Cr | 17 – 19 |
| C | 0.08 max |
| N | 0.10 max |
| Fe | Balance |
| Mn | 2 max |
| Si | 0.75 max |
| S | 0.03 max |
| P | 0.045 max |
| Ti | 5xC min 0.60% max |
A312 Stainless SteelMechanical Specification of AISI 321 Pipe
| Density | 8.0 g/cm3 |
| Melting Point | 1454 °C (2650 °F) |
| Tensile Strength | Psi – 75000 , MPa – 515 |
| Yield Strength (0.2%Offset) | Psi – 30000 , MPa – 205 |
| Elongation | 35 % |
A312 Stainless Steel Composition Standard
| SS | 321H |
| Ni | 09 – 12 |
| S | 00.03 max |
| N | 00.10 |
| Cr | 17 – 19 |
| Si | 00.75 max |
| Mn | 2 max |
| C | 00.04 – 0.08 |
| P | 00.045 max |
| TI | 00.70 max |
ASTM A312 TP321H Mechanical Properties Table
| SS | TP 321H |
| Tensile Strength minimum (MPa) | 515 |
| Yield Strength 0.2% Proof minimum (MPa) | 205 |
| Elongation minimum (% in 50mm) | 40 |
| Hardness | |
| Rockwell B (HR B) maximum | 95 |
| Brinell (HB) maximum | 217 |
The primary difference between 304L stainless pipe and A312 seamless pipe is the manufacturing process. 304L stainless pipe is welded, whereas A312 seamless pipe is made from a single piece of solid steel and does not have any welds. As a result, A312 seamless pipe offers superior corrosion resistance and strength compared to welded pipes. Additionally, the lack of a weld or seam makes A312 seamless pipes easier to clean and maintain.
When selecting a type of stainless steel pipe for your application, it is important to consider the specific requirements of the application, such as corrosion resistance, strength, maintenance requirements, and cost. 304L stainless pipe may be the better option for applications requiring superior corrosion resistance and strength, such as chemical processing and petrochemical processing, while A312 seamless pipe may be more suitable for applications requiring easy cleaning and maintenance, such as food and beverage processing and marine environments. Ultimately, the selection of the right stainless steel pipe depends on the specific requirements of the application.
