What Steel Plate Is Used In Shipbuilding


Shipbuilding relies heavily on steel as the primary material for ship hulls and other structures. Steel is valued for its high strength, durability, and resistance to corrosion. When selecting steel for shipbuilding, there are several key factors to consider, including strength, weldability, and cost effectiveness.

What is the most common steel plate?

The most common steel plate used in shipbuilding is mild steel. Mild steel has a relatively low carbon content which makes it easy to form and weld, while still providing adequate strength for many marine applications.

Within the broad category of mild steel, further classifications are made based on the shipbuilding steel‘s chemical composition and mechanical properties. Some of the most widely used grades of mild steel in shipbuilding include:

  • A-Grade Steels: These general purpose structural steels have good weldability and are used for a variety of ship structures including hull plating and framing. Common A-grade steels include AH32, AH36, and AH40.
  • D-Grade Steels: These steels offer higher strength than A-grade, allowing for weight savings. They are often used for structural parts of the ship exposed to low temperatures like decks, hatches, and bulkheads. Common grades are DH32 and DH36.
  • E-Grade Steels: These shipbuilding steels have the highest strength and are typically used for components requiring thickness reduction while maintaining strength. Plates, sections and profiles of decks, bulkheads and shell plating often use E-grade steels. EH32 and EH36 are typical grades.

So in summary, mild steel plate grades A, D and E are the most commonly used steel plates due to their good balance of strength, weldability and cost for shipbuilding applications.

What is the most common type of steel plate?

The most common specific type of steel plate used in shipbuilding is ABS Grade A steel.

ABS stands for American Bureau of Shipping, one of the major classification societies that establishes and enforces standards for the marine industry. ABS Grade A steel refers to a standard set by ABS for the chemical composition and mechanical properties of structural steel plates used in ship construction.

Some key attributes of ABS Grade A steel include:

  • Yield strength: This indicates the stress at which the steel starts to plastically deform. For ABS Grade A, minimum yield strength ranges from 235 MPa to 390 MPa depending on the grade. Higher strength enables thinner hull plates.
  • Tensile strength: The maximum stress the steel can withstand before fracture. ABS Grade A tensile strength ranges from 400 to 520 MPa.
  • Elongation: The degree to which the steel can stretch before breaking. Higher elongation allows for more flexibility and impact resistance. ABS Grade A requires over 20% elongation.
  • Corrosion resistance: ABS Grade A has additions of copper, nickel and chromium to improve seawater corrosion resistance. This is vital for hull plates.
  • Weldability: Controlled carbon content and alloying additions ensure good weldability. This enables joining of hull plates.

In summary, ABS Grade A steel has an optimal balance of strength, ductility, weldability, and corrosion resistance vital for shipbuilding. This makes it one of the most widely used and trusted marine steel plate types.

Why is steel the most preferred material for shipbuilding?

Steel is the dominant material used in shipbuilding compared to other alternatives like aluminum, fiberglass, and wood. There are several key reasons why steel is the most preferred choice:

  • Strength: Steel has excellent strength, especially relative to its weight. It has high yield and tensile strengths to withstand the stresses of bouyancy, cargo loads, weather, and motion at sea. This enables thinner hull plates to support heavy loads.
  • Durability: Steel has outstanding fatigue strength and toughness for the long working life demanded of ocean-going vessels. It can flex and deform under cyclic stresses yet continue to perform. Steel also resists wear, abrasion, and impacts well.
  • Weldability: Most steel grades used in shipbuilding have composition optimized for welding. Joints between steel plates can be efficiently welded to construct complex ship structures. Other metals like aluminum are more difficult to weld.
  • Corrosion resistance: Modern shipbuilding steel has alloy additions that form protective oxide layers to resist seawater corrosion. Coatings provide further corrosion defense. This is vital for hull integrity.
  • Cost effectiveness: Steel is more affordable than other high-strength metals. And less material is needed owing to steel’s high strength-to-weight ratio. This makes steel very economical for shipbuilding.

In summary, steel combines high strength, weldability, toughness, durability, and corrosion resistance at relatively low cost. This blend of characteristics makes steel the most preferred and widely used shipbuilding material.

What material is used for ship hull plates?

The vast majority of all ship hull plating uses steel plate. Hull plating constitutes the outer shell of the vessel and experiences the most direct contact with water, requiring high strength, durability, and corrosion resistance.

More specifically, the most common steel used for hull plating is ABS Grade A steel or other mild steel plate grades like AH36 high-strength structural steel. The material requirements depend on the hull thickness, location, and required strength.

Key reasons why steel is overwhelmingly the preferred material for hull plates:

  • Strength: Hull plating experiences forces from wave impacts, water pressure, propulsion systems, and cargo loads. Steel provides the high yield strength required to withstand these stresses.
  • Thin construction: The high strength of steel allows for thinner hull construction versus other materials, saving weight and space.
  • Fatigue resistance: Crucial for a structure undergoing cyclic stresses from waves and operation at sea. Steel has excellent fatigue strength.
  • Corrosion resistance: Seawater is extremely corrosive. Steel can be alloyed and coated to resist corrosion far better than other mainstream options.
  • Repairability: Steel hull plates are easily welded and repaired. This facilitates maintenance over the ship’s service life.
  • Cost: Steel is one of the most affordable plate materials providing high strength. This keeps construction costs down.

While some niche uses of aluminum, fiberglass, concrete, or wood exist in shipbuilding, steel overwhelmingly dominates material selection for ship hull plates, owing to its uniquely well-balanced properties.

What is P&O steel plate?

P&O stands for pressure and offshore grade steel plate optimized for marine applications. P&O steels are special shipbuilding steels designed to withstand the extreme demands of offshore oil & gas operations.

Key properties and uses of P&O steel grades:

  • High strength: With yield strengths of over 400 MPa, P&O steels allow construction of lighter vessels and rigs along with thinner plates.
  • Toughness: Outstanding toughness and fatigue strength for offshore assets facing severe cyclic stresses from waves, wind, and operations.
  • Weldability: Clean composition ensures excellent weldability for efficient fabrication of offshore structures. Preheating often required.
  • Resistance: P&O steels exhibit excellent resistance to seawater corrosion and hydrogen-induced cracking.
  • Low temperature: Some grades specially formulated for strength and toughness in frigid, northern waters.
  • Uses: Jack-up rig legs, foundations, hulls, decks, flares, boat landings, offshore platforms, FPSOs.

In summary, P&O specialty steels deliver the combination of high strength, fracture toughness, weldability, and environmental resistance needed for the most demanding offshore oil & gas applications.

What is ASTM A131 steel plate?

ASTM A131 is a standard specification for structural steel plate often used in shipbuilding. It is overseen by ASTM International.

Some key attributes of ASTM A131 steel:

  • Strength: A131 specifies minimum yield strengths from 235 MPa to 390 MPa, depending on grade. This provides the required strength for ship structures.
  • Chemistry: The composition is restricted to enhance weldability and toughness. Additions of Ni, Cr, Mo improve corrosion resistance.
  • Testing: A131 sets testing methods to verify mechanical properties like tensile and Charpy V-notch impact toughness.
  • Acceptance criteria: Standards for surface finish, imperfections, straightness, and roundness ensure quality.
  • Documentation: Mill test reports detail the plate’s properties and compliance with A131.
  • Uses: A131 steel is commonly used for hull, cargo tanks, decks, bulkheads, superstructures and other parts.

In summary, ASTM A131 defines requirements to produce general purpose structural steel suited for shipbuilding applications requiring good strength, weldability and seawater corrosion resistance.

How thick are ship plates?

The plate thickness used for ship hulls and structures varies based on the type, size, and purpose of the vessel. However, typical plate thicknesses range from about 15 mm to 200 mm (0.6” – 8”).

The hull shell plating is generally the thickest plate, ranging from 15 mm for small vessels up to 100 mm for very large ships like bulk carriers and oil tankers. Deck plating is typically between 20 to 50 mm thick. Bulkhead plating usually ranges from 15 mm to 60 mm thickness.

Key factors determining plate thickness needs:

  • Overall ship size and dimensions
  • Loads from cargo, equipment, propulsion system
  • Required hull girder strength
  • Environmental conditions like wave, wind impacts
  • Regulations and classification society rules

Thinner plates help reduce weight, but sufficient thickness must be maintained to provide necessary structural strength. High-strength steel allows for thinner plates while still providing enough load capacity.

In summary, typical marine steel plates range between 15 mm and 200 mm thickness, with hull shells at the thicker end and decks and bulkheads thinner. Plate thickness is tailored for each vessel’s structural requirements.

How thick is ship metal?

Ship metal refers to the steel used to construct the hull and other structural parts of marine vessels. This includes steel plates, stiffeners, frames, beams, and associated fittings like brackets.

The thickness of ship metal varies widely based on the specific structural member and requirements:

  • Plating: Main hull plating ranges from 15 mm up to 100 mm thickness. Deck plating is around 20-50 mm. Bulkhead plating is 15-60 mm typically.
  • Stiffeners: Stiffening members like flats and angles are typically 8-15 mm thick. More substantial stiffeners may reach 20-30 mm.
  • Beams: Transverse frames and girders usually range from 15 mm thickness on smaller vessels to 50+ mm for very large ships.
  • Pillars: Support pillars can be over 100 mm thick in critical locations.

So in summary, ship metal thicknesses range from around 5 mm for secondary structures up to over 100 mm for integral load-bearing members on large vessels. The thickest plates are found on the hull shell. Key determinants of thickness are structural loads, plate size, and materials strength.

Proper thickness optimization reduces weight while ensuring necessary strength for seagoing operations.

Which metal is used to ship?

The overwhelmingly dominant metal used in shipbuilding is steel. Steel accounts for around 90-95% of all metal used to construct the hull, decks, bulkheads, and other structural parts of ships.

Key reasons steel is by far the most common shipbuilding metal:

  • Strength: Steel offers excellent yield and tensile strength, allowing for thinner plates compared to other metals. This maximizes cargo capacity.
  • Weldability: Most shipbuilding steels are optimized for welding fabrication. This enables efficient joining during construction.
  • Toughness: Steel has high ductility and impact toughness to withstand cyclic stresses from waves, loading, and motion at sea.
  • Corrosion resistance: Steel can be alloyed and coated to resist deterioration from exposure to seawater. Maintains structural integrity.
  • Cost: Steel is more affordable than other high-strength metals, keeping shipbuilding costs reasonable.
  • Availability: Steel is widely produced globally, ensuring consistent availability for shipyards.

While small amounts of aluminum are used for some superstructures, the properties of steel make it vastly superior for primary marine structural applications. When choosing metals to ship, steel clearly stands above the rest.

In summary, steel is the dominant metal used in shipbuilding, accounting for around 90-95% of all metal used. It offers the optimal balance of strength, weldability, toughness, corrosion resistance, and cost needed for marine vessels.

Why Choose Gnee Steel

If you want to find a trustable steel products manufacturer, Gnee will be your best choice. 15 years of experience steel products manufacturer, certified by the classification society, CE, ISO, and SGS. And we guarantee the highest safety and quality standards. We fulfill all requirements of reputed classification societies.

In addition, our steel has been successfully exported to more than 60 countries such as Germany, South Korea, the United States, Mexico, and Argentina. Many regular customers come to visit our company and factory and make multiple orders.

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What Services Does Gnee Provide?
  • Dimensional Inspection: Length, width, diameter; Thickness, straightness; Flatness, profile;
  • Surface Inspection: Visual inspection; Roughness testing; Coating thickness measurement;
  • Composition Testing: Interstitial elemental analysis - C,S,P, Si; Alloy grading verification; Inclusion rating;
  • Mechanical Testing: Tensile strength, yield strength; Toughness, ductility; Hardness testing;
  • Flaw Detection: Ultrasonic, radiographic testing; Magnetic particle, dye penetrant testing;
  • Documentation: Inspection reports; Test certificates; Material traceability
  • CNC machining - turning, milling, drilling
  • Surface treatments like polishing
  • Heat treatments - quenching, annealing
  • Wet/powder coating
  • Waterjet cutting
  • Laser cutting
  • Plasma cutting
  • Shearing/punching
Molding and Manufacturing1
  • Rolling
  • Press braking
  • Plate bending - concave & convex
  • Profile bending -custom fabrication as per drawings
  • Chemical analysis
  • Mechanical testing
  • Non-destructive examination
  • Ultrasonic, radiography testing

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