2026 Anchor Chain New Regulation – M4 Grade (CM770): Is It Available Now?
In January 2026, the anchor chain material standard GB/T 18669-2025 officially came into effect — officially incorporating M4 grade (CM770) anchor chain steel into the national standard.
But for procurement professionals and technical managers, the core question is not "what changed in the standard" — it's: Can M4 grade anchor chain be purchased now? Can it be installed on vessels?
This article answers that question directly.
3 Core Changes in the 2026 New Regulation
GB/T 18669-2025 "Steel for Marine Anchor Chains and Mooring Chains" took effect on January 1, 2026, with three core changes:
1. New M4 Grade Anchor Chain Steel Added
CM770 (minimum tensile strength ≥770 MPa) was formally established as the dedicated material grade for M4 anchor chains.
2. New R6 Grade Mooring Chain Added
The mooring chain material system was simultaneously upgraded, with R6 grade incorporated into the standard.
3. Expanded Scope of Application
Applicable to hot-rolled marine anchor chain steel with nominal diameters from 13mm to 225mm.
At the standard level, M4 grade now has complete coverage from product standard (GB/T 549-2017) to material standard (GB/T 18669-2025) — one of the most significant changes in the 2026 regulation.
M4 vs M3 Comparison
| Grade | Material | Tensile Strength | Standard Basis | Status |
| M2 | CM490 | ≥490 MPa | GB/T 549-2017 | Mature, mass-produced |
| M3 | CM690 | ≥690 MPa | GB/T 549-2017 | Mature, mass-produced |
| M4 | CM770 | ≥770 MPa | GB/T 549-2017 + GB/T 18669-2025 | Standard in place, material awaiting production |
Technical differences:
- M4 is approximately 12% stronger than M3. At the same 50mm diameter, breaking load is approximately 27% higher.
- Engineering value of M4: under the same load requirements, smaller diameter chains can be used to achieve vessel weight reduction and chain locker space optimization.
Current Status of M4 Grade Anchor Chain
Since the 2026 regulation took effect, the actual status across each link of the supply chain is as follows:
| Dimension | Current Status (2026) |
| Product Standard | GB/T 549-2017 already includes M4, implemented 2017 ✅ |
| Material Standard | GB/T 18669-2025 specifies CM770, implemented January 2026 ✅ |
| Steel Mill Supply | CM770 not yet mass-produced; currently in R&D and market demand assessment phase |
| Classification Society Approval | CCS has opened certification channels; other societies have not yet begun |
| Anchor Chain Manufacturer Readiness | Yasing, Zhongyun have listed in catalogs; Qingdao Anchor Chain, Wancheng no public M4 activity |
| Actual Deliveries | No public records of batch deliveries |
Key takeaway: Standards are in place. Materials are not yet produced. Batch application still requires waiting.
Frequently Asked Questions
Q1: Can M4 grade anchor chain be purchased now?
Anchor chain manufacturers have listed M4 grade parameters in their catalogs. However, there is a gap between "product design meets specification" and "factory approval obtained + material mass production secured." CM770 material is not yet mass-produced. For projects with special weight reduction or strength requirements, we recommend discussing technical specifications early. For conventional projects, M3 remains sufficient.
Q2: How much weight can M4 actually save?
Using 50mm chain diameter as an example: M3 breaking load is 1,960 kN, M4 breaking load is 2,490 kN. Under the same load requirements, M4 may allow chain diameter reduction of 1-2 sizes. For a VLCC with approximately 1,100 meters of chain across 4 lines, a 2mm diameter reduction could save approximately 8-10 tons of total vessel weight. Exact figures depend on vessel type, chain length, and design loads — but the direction is clear: M4's weight-saving value is its core selling point.
Q3: What is the difference between M4 and R3/R4?
M series (M2/M3/M4) are anchor chains for vessel anchoring, with high strength as the core performance priority. R series (R3/R4/R5/R6) are mooring chains for offshore platforms and FPSO long-term station-keeping, with seawater corrosion resistance, fatigue resistance, and low-temperature toughness as the core priorities. They belong to different standard systems, serve different applications, and are not interchangeable.
Recommendations for Procurement and Specification
| Project Type | Recommendation on M4 |
| Conventional commercial vessels | No need to consider M4; M3 is proven and reliable |
| Projects with weight reduction or strength upgrade requirements | Monitor M4 progress; recommend early technical discussion with suppliers |
| High-value-add projects | Monitor CCS certification progress; stay in touch with suppliers for updates |
| Future newbuild projects | Consider including "M4 or equivalent" as an option in specifications to maintain flexibility |
The 2026 anchor chain regulation has completed the coverage from product definition to material specification for M4 grade anchor chains. However, standard-setting is only the first step. Large-scale application of M4 grade anchor chains still depends on market demand and gradual maturation of the industrial supply chain.
SMEOCEAN continuously tracks the evolution of anchor chain industry standards and the progress of M4 grade certification. If you need the full text of the 2026 regulation, M4 technical specifications, or would like to discuss specific project requirements, please feel free to contact us.
More Links:
CM690 76mm Stud Link Anchor Chain – Manufacturing Process
Anchor Chain Wear Limit: SMEOCEAN Safety Guide for Ship Lifeline
What are Anchor Chains Used for ?