P355NL1 and P355NL2 are both steel grades used primarily in pressure vessel and boiler applications, and they are specified under the European standard EN 10028-3.
P355NL1 Steel Plate Procurement Guidance
P355NL2 Steel Plate Procurement Guidance
While they share many similarities, there are key differences between them:
Table 1: Chemical Composition of EN 10028–P355NL1/NL2
Table 2: Mechanical Properties of EN 10028 – P355NL1/NL2
P355NL1:
Yield Strength: 355 MPa minimum.
Tensile Strength: 490 to 620 MPa.
Elongation: Minimum of 22% in 50 mm.
P355NL2:
Yield Strength: Also has a minimum yield strength of 355 MPa.
Tensile Strength: Similar range of 490 to 620 MPa.
Elongation: Minimum of 22% in 50 mm.
Impact Properties
P355NL1 is designed for low-temperature applications and has better impact toughness at -50°C (-58°F).
P355NL2 is also suitable for low-temperature applications, but it has slightly lower impact toughness requirements than P355NL1. The typical temperature for P355NL2's impact tests is around -20°C (-4°F).
The different types of P355 steel and other boiler quality steels, such as A516 (A516.60 and A516.70) and SA 516 (SA 516.60 and SA 516.70) according to the ASME classification, are used for the construction of pressure tanks and vessels, heat exchangers and components required for storage under pressure, such as valves.
P355 steel can be further classified into p355nl1, p355nl2, p355nh, P355gh and p355nh. The additional letters that follow the nomenclature indicate the use of the alloy at high (nl) and low (nh) temperatures.
Applications
Both grades are commonly used to manufacture pressure vessels, heat exchangers, and other components that require high strength and good weldability.
P355NL1 is often preferred in very low-temperature environments due to its superior toughness.
Summary
In summary, the primary difference between P355NL1 and P355NL2 lies in their impact toughness at low temperatures, with P355NL1 offering better performance. This makes P355NL1 more suitable for applications where extremely low temperatures are expected.
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