Difference between SPV355 and SPV410 steel plate

SPV355 and SPV410 are pressure vessel quality steel plates manufactured to Japanese Industrial Standard JIS G3115, specifically designed for intermediate temperature service in welded pressure vessels, boilers, and storage tanks. The "SPV" designation stands for Steel Plate for Vessels, and the number indicates the minimum tensile strength in MPa. These grades are widely used in oil refineries, chemical plants, and thermal power stations where reliable performance at elevated temperatures is essential.

Key Differences:

The fundamental distinction is their strength level. SPV355 has a minimum tensile strength of 355 MPa (with minimum yield strength typically ≥ 205 MPa depending on thickness), while SPV410 offers a higher minimum tensile strength of 410 MPa (with minimum yield strength typically ≥ 235 MPa or higher). This makes SPV410 capable of withstanding greater internal pressures, allowing for reduced wall thickness in pressure vessel design.

To achieve this higher strength, SPV410 requires a more refined chemical composition with higher carbon and manganese content compared to SPV355. Typically, SPV410 also involves more precise micro-alloying control during the rolling process. Consequently, SPV410 has a higher carbon equivalent (Ceq) than SPV355. This results in more demanding fabrication requirements, particularly regarding welding. SPV410 necessitates stricter control of preheating temperatures, mandatory use of low-hydrogen welding consumables, careful management of heat input, and often more rigorous post-weld heat treatment (PWHT) to prevent hydrogen-induced cracking and ensure the integrity of welded joints in pressure vessel construction. SPV355, with its lower carbon equivalent, offers better weldability and slightly easier fabrication while still providing reliable performance for moderate-pressure applications. 

Chemical Composition

Mechanical Property