ASTM A420-WPL6 or ASTM A234-WPB
What is ASTM A420 WPL6 material?
ASTM A420 WPL6 is a typical low temperature material grade for Butt weld pipe fittings.
The most important character for ASTM A420 WPL6 is used for low temperature enviorement therefore,all the pipe fittings shall be impact tested and
The impact test temperature shall be -50°F[-45°C] for ASTM A420 Gr. WPL6.
ASTM A420 WPL6 Seamless Pipe fittings are made of ASTM A333 grade 6 seamless pipe.
While ASTM A420 WPL6 welded pipe fitting could be made from the steel plate ASTM A516 Gr.60 via butt welding process.
Pipe fittings manufactured to ASTM A420 shall take the following tests or inspections: dimensional inspection, visual examination, chemical analysis, tensile test, impact test, radiographic test if welded fittings (RT).
Chemical Composition of ASTM A420 WPL6
| C | Mn | P | S | Si | Ni | Cr | Mo | Cu | Cb | V |
|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.30 | 0.50~1.06 | ≤0.035 | ≤0.040 | 0.15~0.40 | ≤0.40 | ≤0.30 | ≤0.12 | ≤0.40 | ≤0.02 | ≤0.08 |
*All values are in % unit.
2. Mechanical Properties of ASTM A420 WPL6
| Tensile Strength, min. | Yield Strength, min. | Elongation (2 in.), min. | |||
|---|---|---|---|---|---|
| ksi | MPa | ksi | MPa | Longitudinal, % | Transverse, % |
| 60~95 | 415~655 | 35 | 240 | 30 | 16.5 |
3. Charpy Impact Requirements of ASTM A420 WPL6
| Size of Specimen | A* | B* | ||
|---|---|---|---|---|
| mm | ft·lbf | J | ft·lbf | J |
| 10 by 10.0 | 13 | 17.6 | 10 | 13.6 |
| 10 by 7.5 | 10 | 13.6 | 8 | 10.8 |
| 10 by 5.0 | 7 | 9.5 | 5 | 7.0 |
| 10 by 2.5 | 4 | 5.4 | 3 | 4.1 |
*A – Charpy V-Notch Impact Value Required for Acceptance (Average of Three Specimens).
*B – Minimum Charpy V-Notch Impact Value Without Requiring Retest (One Specimen Only of a Set).
*The impact test temperature shall be -50°F[-45°C] for ASTM A420 Gr. WPL6.
ASTM A234 WPB fittings
are commonly used in piping systems for various industries, including oil and gas, petrochemical, power generation, and chemical processing. They are available in a wide range of sizes and configurations, including elbows, tees, reducers, and caps, to suit different piping requirements.
What is WPB Exactly Meaning?
W = WELDABLE / wrought
P = RELATED TO PIPE OF ALLOY MATERIAL
B = REFER TO MINIMUM YIELD OF MATERIAL,Refer to Grade B
ASTM A234 WPB Pipe fittings is made from the Pipe ASTM A 106 grade B, or API 5L grade B.
ASTM A234 WPB Chemical Composition
| Grade | C | Mn | P | S | Si | |
| ASTM A234 WPB Pipe Fittings | 0.3 | 0.29-1.06 | 0.05 | 0.058 | 0.1 minimum | |
| Grade | Cr | Mo | Ni | Cu | V | Nb |
| ASTM A234 WPB Fittings | 0.4 | 0.15 | 0.4 | 0.4 | 0.08 | 0.02 |
SA234 WPB Mechanical Properties
| Item | Tensile Strength (KSI) | Yield Strength (KSI) |
| ASTM A234 WPB Pipe Fittings | 60 | 35 |
So from above ,we can see that the main difference between ASTM A420-WPL and ASTM A234-WPB as below
1. Material Composition:
- A234 WPB: This grade refers to pipe fittings made from wrought carbon steel. WPB fittings are suitable for moderate to high-temperature service and are commonly used in various industries, including oil and gas, chemical processing, and power generation.
- A420 WPL6: WPL6 fittings are made from low-temperature carbon steel. They are specifically designed to withstand low-temperature environments, making them suitable for applications where cryogenic temperatures are a concern, such as LNG (liquefied natural gas) facilities and refrigeration systems.
2. Temperature Range:
- A234 WPB: WPB fittings are suitable for moderate to high-temperature service, typically ranging from -20°F (-29°C) to 800°F (427°C), depending on the specific application and material specifications.
- A420 WPL6: WPL6 fittings are designed for low-temperature service and can withstand temperatures as low as -50°F (-46°C) without losing their mechanical properties. They offer excellent toughness and impact resistance at cryogenic temperatures.
3. Impact Testing Requirements:
- A234 WPB: While WPB fittings are not typically subjected to impact testing requirements, they must conform to specific chemical composition and mechanical properties outlined in ASTM A234 standards.
- A420 WPL6: WPL6 fittings are subjected to impact testing at low temperatures to ensure their suitability for cryogenic applications. This testing helps verify the material’s ability to withstand sudden loads and maintain structural integrity under extreme conditions.
But nowadays,some manufacturers are producing dual grade A420 WPL6/A234 WPB Pipe fittings,Which means the material composition and machanical property of the fitting can meet both standard.