Product Description:
Material Advantages:
The manufacture of R4-grade mooring chain adheres to strict
standards. For example, China's GB/T 18669-2025 standard specifies
the technical requirements for all grades of mooring chain steel,
including R4. Ship inspection organizations such as the China
Classification Society (CCS) also have corresponding specifications
for mooring chain grades (R3, R3S, R4, R4S, and R5).
The core material is a low-alloy, high-strength steel designed to
ensure the chain's superior strength, corrosion resistance, and
fatigue resistance.
Key Chemical Composition: To achieve R4-grade mechanical
properties, the steel typically contains the following key alloying
elements (based on proprietary technical data):
Carbon (C): 0.16-0.27% for strength and hardness.
Manganese (Mn): 0.40-1.80% for improved strength and toughness.
Chromium (Cr): 0.80-2.50% for enhanced corrosion resistance and
hardenability.
Molybdenum (Mo): 0.10-0.70%, improves strength, hardenability, and
heat resistance.
In addition, trace amounts of silicon (Si), nickel (Ni), and
niobium (Nb) may be included to optimize performance.
Mechanical Performance Requirements: R4-grade mooring chain steel
must meet high mechanical performance requirements, such as a yield
strength of ≥700 MPa and a tensile strength of ≥900 MPa. It must
also exhibit good toughness, such as a Charpy V-type impact energy
of ≥60 J at -30°C.
Manufacturing Process:
The production of R4-grade mooring chain is a multi-step, precision
process. The following table summarizes its main steps and key
points:
Production Steps Core Operations and Key Points
① Cutting: Alloy round steel is cut into sections of the required
length using a saw according to production requirements.
② Heating: The sections are heated in an intermediate frequency
furnace to approximately 1200°C to achieve plasticity. Precise
temperature control (e.g., ±2°C) is required, and a fine grain
structure must be maintained.
③ Ringing and Welding: The hot bar stock is bent into rings on a
ringing machine and flash welded to form the links. Precise control
is required for weld spacing (1-3mm) and alignment tolerances
(≤0.3mm).
④ Deburring: Welding-induced burrs are removed, requiring high
precision (e.g., less than 3%).
⑤ Pressing: The crossbars are installed on the crossbar chain. The
crossbars are reinforced and asymmetrical, and the shaping
tolerances are strict (e.g., ±0.2mm).
⑥ Quenching and Tempering: This is a critical step in ensuring the
strength and toughness of the chain links. The chain links are
first quenched (rapidly cooled) and then tempered to eliminate
internal stresses and stabilize the structure. The entire chain
undergoes a comprehensive heat treatment.
⑦ Tensile Testing: The chain undergoes a tensile test to verify
that its breaking load and tensile properties meet specification
requirements.
⑧ Surface Polishing and Flaw Detection: The chain link surface is
polished, and then non-destructive testing (such as magnetic
particle or ultrasonic testing) is used to detect surface and
internal minor defects.
⑨ Packaging, Varnishing, and Shipping: Qualified chains are
packaged, coated with a special protective varnish (such as epoxy
paint) to prevent corrosion, and finally shipped.
Features:
R4-grade marine mooring chain is a high-performance product
manufactured from low-alloy, high-strength steel (such as
25CrMn2Mo) through a series of precision processes, including
hot-weaving, flash welding, and tempering.
It is important to note that the specific chemical composition and
process parameters may vary depending on the proprietary
technologies of different manufacturers. When purchasing or using
the product, it is important to confirm that it complies with
relevant national or industry standards (such as GB/T 18669) and
obtain material certification and third-party inspection
certificates (such as classification society certificates) from the
manufacturer. This is crucial to ensure the chain can operate
safely and reliably in harsh marine environments.
Technical Parameters:
Applications:
Application Areas Specific Facilities and Uses
Floating Production Systems (FPSOs) are used to securely moor
floating production, storage, and offloading (FPSO) vessels at
their operating locations and are core facilities for offshore oil
and gas production.
Drilling Platforms are used to securely position and stabilize
floating drilling rigs, such as semi-submersible drilling
platforms, during deepwater drilling operations.
Single-Point Mooring Systems (SPMSs), a key component of
single-point mooring structures, connect offshore buoys to the
seabed foundation, allowing tankers to maneuver with wind and
current in adverse sea conditions, reducing stress.
Other Marine Development Facilities Widely used in various marine
exploration and offshore operations.
Support and Services:
R4-grade offshore mooring studded anchor chains are critical
equipment for deepwater oil and gas development and high-tech
marine engineering.
If you're selecting or purchasing for a specific project, in
addition to focusing on the grade, you should also consider:
Adhere to standards: Ensure the product complies with the latest
national standards (such as GB/T 18669-2025) or international
standards (such as ISO 20438:2017).
Obtain certification: Require suppliers to provide product
certifications from reputable classification societies (such as
CCS, ABS, DNV, etc.). This is a crucial safety guarantee.
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