CB/T 4568-2025 in English
VALIDMarine Shackle
- Issued on:2025-04-10
- Implemented on:2025-11-01
- File Format:PDF
- Delivery:Via email within 5 business days
$437.00
| Standard No: | CB/T 4568-2025 |
| Document status: | VALID |
| Title in English: | Marine Shackle |
| Title in Chinese: | 船用卸扣 |
| Language: | English |
| File Format: | Electronic (PDF) |
| Delivery: | Via email within 5 business days |
| Issued on: | 2025-04-10 |
| Implemented on: | 2025-11-01 |
| ICS Classification: | 47.020.50-Deck equipment and installations |
| Chinese Classification: | U26-Deck fittings |
| Professional Classification: | CB-Watercraft |
| Related Keywords: | marine shackle introductionin-depth analysis
4568-2025 ship shackle standardcb/t straight shackle ship shackle products shackle body |
Introduction
In-Depth Analysis of the CB/T 4568-2025 Ship Shackle Standard
CB/T 4568-2025, a key standard for connectors in the shipbuilding industry, will be officially released and implemented in 2025, completely replacing the 1999 edition of CB/T 32. This standard, issued by the Ministry of Industry and Information Technology of the People's Republic of China, was proposed by China State Shipbuilding Corporation (CSIC), under the jurisdiction of the National Technical Committee for Shipbuilding Standardization, and drafted by Jiangnan Shipyard (Group) Co., Ltd., reflects the latest achievements in standardization in my country's shipbuilding industry.
Background of Standard Revision and Technological Evolution
This standard dates back to GB 559-1965, first issued in January 1966. It underwent its first revision in 1987, was restructured into the shipbuilding industry standard CB/T 32-1999 in June 1999, and finally underwent this major revision in 2025. Technological evolution is primarily reflected in the optimization of shackle structures, strengthened inspection requirements, and expanded scope of application. Comparison of Key Technical Changes: Compared to the 1999 edition, the new standard removes outdated structures such as straight shackles with cylindrical pins, circular shackles with cylindrical pins, and oversized circular shackles with cylindrical pins. It also adds modern quality management content, including requirements, test methods, packaging, transportation, and storage. It also updates the diagrams of shackle node types, making the standard more aligned with modern shipbuilding needs. The standard categorizes shackles into two main types based on body shape: straight shackles and circular shackles. It further subdivides these shackles into nine types based on the connection method between the cross pin and the body, forming a complete classification system. Straight shackles include D1 straight shackles with shoulder threads, D2 straight shackles with countersunk threads and D3 straight shackles with hexagonal head bolts; round shackles include 01, 02, 03 and their corresponding enlarged 0E1, 0E2 and 0E3 types.
| Shackle type | Model code | Rated load range (kN) | Main application features | |||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Straight shackle | D1 | 3.9-784.0 | Shoulder thread connection, uniform load | |||||||||||||||||
| D2 | 3.9-784.0 | Countersunk thread connection, smooth appearance | ||||||||||||||||||
| D3 | 3.9-784.0 | Hexagonal head bolt connection, easy disassembly | ||||||||||||||||||
| 01 | 3.9-784.0 | Standard round type, strong versatility | ||||||||||||||||||
| 02 | 3.9-784.0 | Countersunk thread round type | ||||||||||||||||||
| 03 | 3.9-784.0 | Hexagon head bolt round type | ||||||||||||||||||
| 0E1 | 3.9-245.0 | Enlarged shoulder thread | ||||||||||||||||||
0 The standard sets strict requirements for the dimensional accuracy of shackles. For example, when the rated load is 3.9kN, the nominal value of the B dimension is 13mm, with an allowable deviation of +0.65mm. When the rated load reaches 784.0kN, the nominal value of the B dimension is 177mm, with an allowable deviation of +9.0mm. This graded accuracy requirement ensures the applicability of shackles of different specifications. Material and Manufacturing Process SpecificationsMaterial Selection RequirementsThe standard clearly stipulates that the shackle body should be forged from a single, seamless blank using 25# high-quality carbon structural steel, the cross pin from 35# high-quality carbon structural steel, and the nut from Q235B carbon structural steel. All materials must comply with the relevant requirements of GB/T699-2015 and GB/T700-2006, and production may only begin after passing material inspection. Material Quality Control Key Points: Forgings must comply with the requirements of GB/T12362, "Tolerances and Machining Allowances for Steel Die Forgings," to ensure forging quality. The hardness of the body after heat treatment should not exceed HB217 or HRC17. This requirement ensures the shackle has both sufficient strength and appropriate toughness during use. Surface treatment processThe standard requires that all shackle parts shall be hot-dip galvanized according to CB/Z 343, and the thickness of the galvanized layer shall not be less than 70μm. This requirement significantly improves the corrosion resistance of the shackle in the marine environment and extends its service life. The rust removal level of the steel before surface treatment shall comply with the requirements of GB/T 8923.1-2011 to ensure the quality of the coating. Strength verification and inspection requirementsLoad verification systemThe standard establishes a complete load verification system: the verification load is 2 times the rated load, and the minimum breaking load is 4 times the rated load. The shackle should be able to withstand the static load of the verification load, the cross pin should not have permanent deformation after unloading, and it can rotate freely after loosening. The increment of the body length dimension H shall not exceed 0.25% or 0.5mm (the larger value).
Inspection rules systemThe standard divides inspection into two categories: type inspection and factory inspection. Type inspection applies to initial production, major changes in structural materials and processes, and major accidents in mass production; factory inspection is a piece-by-piece inspection. Inspection items include material, hardness, strength, dimensions, surface treatment, and appearance quality. Inspection Implementation Key Points: For type inspection, two samples of each model are drawn. They are considered qualified if all items meet the requirements. If any non-conformities are found, double sampling and re-inspection are permitted. During factory inspection, if the material inspection fails, the entire batch of shackles is deemed unqualified; if other items fail, double sampling and re-inspection may be permitted. Marking and Packaging and Transportation SpecificationsMarking System DesignThe standard establishes a unified marking system. For example, a D1-type shouldered threaded straight shackle with a rated load of 9.8kN is marked "Shackle CB/T32-XXXX D1-1.0." The marking must be centered, with clear and distinct fonts and a steel stamp to ensure permanence and legibility. Packaging and Transportation RequirementsSmall-tonnage shackles should be packaged securely in boxes lined with a moisture-proof lining. The product and accessories must be securely fastened within the packaging to prevent damage during transport. The technical documentation delivered with the product, including the product certificate and operating and maintenance instructions, must be packaged in moisture-proof bags. Standard Implementation Recommendations and PrecautionsDesign and Selection RecommendationsDuring the ship design phase, the shackle type and specifications should be appropriately selected based on actual operating conditions. For critical load-bearing areas, it is recommended to select shackles with a rated load margin with a certain safety margin, taking into account the corrosion effects of the marine environment. When selecting a shackle, pay particular attention to the markings and identification of the shackle to ensure the correct model is used. Quality Control Key PointsDuring the manufacturing process, strict control must be exercised over material quality, heat treatment processes, and surface finish quality. Inspection should focus on key indicators such as hardness, proof load, and dimensional accuracy. Upon receiving the shackle, the user should inspect the certificate of conformity, including manufacturer information, product model, production date, inspection seal, and material quality. Maintenance Recommendations: Shackles should be stored in a well-ventilated area to prevent contact with acids, alkalis, and salts. During regular inspections, focus on thread fit, surface corrosion, and marking clarity, and replace them promptly if any problems are found. For shackles used in harsh environments for long periods of time, it is recommended to shorten the inspection cycle. Standardization Benefit AnalysisThe implementation of CB/T 4568-2025 will significantly improve the quality and technical consistency of my country's ship shackle products, and will promote international trade and technological exchanges. The unified specifications of the standard reduce safety hazards caused by inconsistent specifications and improve the safety and reliability of ship operations. At the same time, the technical requirements of the standard are aligned with mainstream international standards, providing technical support for my country's shipbuilding products to participate in international competition. As an important basic standard for the shipbuilding industry, the improvement and implementation of its technical content will effectively promote technological progress and enhance the quality management level of my country's shipbuilding industry. All relevant units should carefully study the contents of the standard and strictly follow the requirements of the standard in design, manufacturing, inspection and use to ensure safe and reliable ship operations. Sample only — not a preview of CB/T 4568-2025
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