R4 Grade Offshore Mooring Stud Link Marine Ship Anchor Chain

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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