Products FAQ
What is the main difference between DNV Grade A and Grade D shipbuilding steel plates?
The main difference between the two lies in the impact test requirements.
DNV Grade A: Impact testing is not mandatory, or it may be conducted at room temperature (20°C).
DNV Grade D: A Charpy V-notch impact test must be strictly conducted at -20°C.
Therefore, Grade D is more suitable for structures that may be exposed to cold environments, as it effectively resists brittle fracture and offers higher reliability.
In shipbuilding, where is DNV Grade B steel plate primarily used?
It is primarily used for the main structures of vessels under 10,000 tons, or for secondary and non-critical structures of general strength on large vessels (such as superstructures, internal bulkheads, deck platforms, etc.). Since it is designed for operating environments above 0°C, it is well-suited for the construction of ships, barges, and certain coastal fishing vessels intended for operation in coastal, inland waterway, and temperate non-ice-bound waters.
What certifications are required for DNV Grade B shipbuilding steel plates?
The product must hold a valid DNV factory certification (3.1 or 3.2 certificate) and have full traceability. If required for use across classification societies, certifications from ABS, LR, CCS, etc., may also be provided. Third-party inspections (such as SGS or BV) can be provided upon customer request.
Can DNV Grade B shipbuilding steel plates be used for offshore oil and gas platforms?
Yes, DNV Grade B shipbuilding steel plates are widely used for secondary structural components in offshore platforms and barges. However, for primary, heavy-duty, or polar environments, high-strength shipbuilding steel plates such as DNV AH32, AH36, DH32, DH36, EH32, and EH36 are typically preferred.
What is the main difference between DNV Grade A shipbuilding steel plates and DNV Grade B shipbuilding steel plates?
The main difference lies in the impact toughness requirements. DNV Grade A shipbuilding steel plates do not require mandatory impact testing for plates with a thickness of ≤50 mm (or testing at room temperature). In contrast, DNV Grade B steel plates must undergo mandatory Charpy V-notch impact testing at 0°C to ensure higher structural safety in colder marine climates.
Does DNV Grade B shipbuilding plate require heat treatment?
Standard thin plates can be supplied in the as-rolled condition; however, for plates thicker than 40 mm, it is recommended to use the normalized delivery condition to refine the grain structure, eliminate internal stresses, and improve the toughness and weldability of the thick plate.
Is DNV Grade A shipbuilding steel plate safe for use at low temperatures?
No, it is not safe. DNV Grade A shipbuilding steel plate is not required to undergo Charpy V-notch impact testing, so its low-temperature toughness cannot be guaranteed, and there is a risk of brittle fracture. This steel is not suitable for low-temperature environments; if service at low temperatures is required, DNV Grade D (-20°C) or Grade E (-40°C) should be selected.
Do you provide mill test certificate for DNV Grade A shipbuilding steel plates?
Yes. Our DNV Grade A (NV A) shipbuilding steel plates are shipped with DNV-certified mill test tertificate. Third-party inspection reports (such as SGS or BV) can also be provided upon request.
What are the weldability characteristics of DNV Grade A shipbuilding steel plates?
Yes. This steel grade has a low carbon equivalent (CEV ≤ 0.40%), resulting in excellent weldability. Thin plates can be welded using conventional MMA/MIG welding without preheating; for plates thicker than 50 mm, low-temperature preheating is recommended to prevent cold cracking.
Where is DNV Grade A shipbuilding plate typically used?
Non-critical components in cargo ships, barges, and coastal vessels, including secondary hull sections, decks, bulkheads, and superstructures; as well as in offshore platforms, ship repair projects, and inland waterway vessel construction.
