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Interpretation of the national standard for crane hooks (GB/T10051)

2025-07-29 00:17:52

The following is a detailed interpretation of the Chinese national standard  GB/T 10051 "Lifting Hooks"  , covering the core content, technical points and practical application guidance:

1. Standard Architecture

GB/T 10051 is a series of standards, including the following parts:

  • GB/T 10051.1 : Mechanical properties, lifting capacity, stress and materials of lifting hooks

  • GB/T 10051.2 : Technical requirements for straight handle lifting hooks

  • GB/T 10051.3 : Technical requirements for forged lifting hooks

  • GB/T 10051.4 : Inspection of the use of straight handle lifting hooks

  • GB/T 10051.5 : Technical requirements for stacked hooks for lifting hooks

2. Core Technology Requirements

1.  Material requirements (GB/T 10051.1)

  • Material Grade :

    • Forged hooks: must be made of  high-quality alloy steel (such as 34CrMo, 34CrNiMo6), with sulfur and phosphorus content ≤ 0.035%;

    • Laminated hook: The steel plate must comply with Q690D and above in GB/T 1591.

  • Mechanical properties :

    index Forged Hook Requirements Laminated hook requirements
    tensile strength ≥785 MPa ≥690 MPa
    Yield Strength ≥590 MPa ≥550 MPa
    Elongation ≥15% ≥16%

2.  Manufacturing process (GB/T 10051.3)

  • Forging process :

    • Die forging  or  free forging + finishing must be used  , casting is prohibited;

    • The thread accuracy of the hook handle must reach  6g level (GB/T 197).

  • Heat Treatment :

    • After quenching and tempering (quenching + tempering), hardness range is  HB 207~255 ;

    • 100% hardness gradient test is required  , and the hardness difference of the same hook body is ≤15HB.

3.  Safety factor and load (GB/T 10051.1)

  • Design safety factor :

    • Static load safety factor ≥4.0 (4 times the rated load);

    • Fatigue safety factor ≥1.8 (based on 100,000 cycles of loading).

  • Test load :

    Test Type Load requirements Eligibility criteria
    Factory test 1.25 times rated load No permanent deformation
    Type test 2.0 times rated load No cracks

3. Inspection and Acceptance

1.  Nondestructive testing (GB/T 10051.3)

  • NDT requirements :

    • 100% magnetic particle testing (MT) : hook surface crack detection (sensitivity A1 test piece);

    • Ultrasonic flaw detection (UT) : internal defect detection (Φ2mm flat bottom hole equivalent).

  • Defect determination :

    • Cracks and white spots: directly scrapped;

    • Single pore ≤Φ1.5mm (depth ≤3mm).

2.  Dimensional tolerance (GB/T 10051.2)

  • Hook width deviation: ±1% rated opening size;

  • Hook handle straightness: ≤0.5mm/100mm.

IV. Usage and scrapping standards (GB/T 10051.4)

1.  Regular inspection

  • Daily inspection : cracks on the hook surface and wear on the hook mouth;

  • Annual comprehensive inspection : including UT re-inspection and load test.

2.  Compulsory scrapping conditions

  • The hook mouth is deformed by more than 10% of its original size  ;

  • The dangerous section wear reaches  5% of the original size (the wear of a single laminated hook is ≥3%);

  • Cracks  or  plastic deformation occur in any part  .

5. Relationship with other standards

  • Compared with ISO : GB/T 10051.3 is equivalent to  ISO 3076 , but the fatigue test requirements are more stringent;

  • Special equipment specifications :  The additional requirements of TSG Q0002-2023 "Technical Safety Regulations for Hoisting Machinery" must be met at the same time  .

VI. Implementation suggestions for enterprises

  1. Selection and procurement :

    • Suppliers are required to provide  material report + flaw detection report + heat treatment record ;

    • Priority will be given to units that participated in the drafting of standards (such as Shanghai Zhenhua and Weihua Group).

  2. Quality Control :

    • Conduct hardness sampling before storage  (≥5% for each batch);

    • Use  a laser rangefinder  to monitor the deformation of the hook mouth.

  3. Compliance Management :

    • Establish  a full life cycle archive of the hook (including test data and maintenance records);

    • Scrapped hooks must  be physically destroyed  to prevent misuse.

7. Common Non-Conformities

  • Material substitution : using non-standard steel from small steel mills to impersonate 34CrMo;

  • Missed flaw detection : Only MT is performed without UT, and internal defects are ignored;

  • Refurbishment abuse : Secondary use after privately welding to repair cracks.

Summary : GB/T 10051 ensures hook safety through full-process specifications for materials, processes, and testing. Companies need to combine TSG Q0002 with actual working conditions to develop stricter internal control standards (e.g., tightening the scrap wear limit from 5% to 3%).

The following is a detailed interpretation of the Chinese national standard  GB/T 10051 "Lifting Hooks"  , covering the core content, technical points and practical application guidance:

1. Standard Architecture

GB/T 10051 is a series of standards, including the following parts:

  • GB/T 10051.1 : Mechanical properties, lifting capacity, stress and materials of lifting hooks

  • GB/T 10051.2 : Technical requirements for straight handle lifting hooks

  • GB/T 10051.3 : Technical requirements for forged lifting hooks

  • GB/T 10051.4 : Inspection of the use of straight handle lifting hooks

  • GB/T 10051.5 : Technical requirements for stacked hooks for lifting hooks

2. Core Technology Requirements

1.  Material requirements (GB/T 10051.1)

  • Material Grade :

    • Forged hooks: must be made of  high-quality alloy steel (such as 34CrMo, 34CrNiMo6), with sulfur and phosphorus content ≤ 0.035%;

    • Laminated hook: The steel plate must comply with Q690D and above in GB/T 1591.

  • Mechanical properties :

    index Forged Hook Requirements Laminated hook requirements
    tensile strength ≥785 MPa ≥690 MPa
    Yield Strength ≥590 MPa ≥550 MPa
    Elongation ≥15% ≥16%

2.  Manufacturing process (GB/T 10051.3)

  • Forging process :

    • Die forging  or  free forging + finishing must be used  , casting is prohibited;

    • The thread accuracy of the hook handle must reach  6g level (GB/T 197).

  • Heat Treatment :

    • After quenching and tempering (quenching + tempering), hardness range is  HB 207~255 ;

    • 100% hardness gradient test is required  , and the hardness difference of the same hook body is ≤15HB.

3.  Safety factor and load (GB/T 10051.1)

  • Design safety factor :

    • Static load safety factor ≥4.0 (4 times the rated load);

    • Fatigue safety factor ≥1.8 (based on 100,000 cycles of loading).

  • Test load :

    Test Type Load requirements Eligibility criteria
    Factory test 1.25 times rated load No permanent deformation
    Type test 2.0 times rated load No cracks

3. Inspection and Acceptance

1.  Nondestructive testing (GB/T 10051.3)

  • NDT requirements :

    • 100% magnetic particle testing (MT) : hook surface crack detection (sensitivity A1 test piece);

    • Ultrasonic flaw detection (UT) : internal defect detection (Φ2mm flat bottom hole equivalent).

  • Defect determination :

    • Cracks and white spots: directly scrapped;

    • Single pore ≤Φ1.5mm (depth ≤3mm).

2.  Dimensional tolerance (GB/T 10051.2)

  • Hook width deviation: ±1% rated opening size;

  • Hook handle straightness: ≤0.5mm/100mm.

IV. Usage and scrapping standards (GB/T 10051.4)

1.  Regular inspection

  • Daily inspection : cracks on the hook surface and wear on the hook mouth;

  • Annual comprehensive inspection : including UT re-inspection and load test.

2.  Compulsory scrapping conditions

  • The hook mouth is deformed by more than 10% of its original size  ;

  • The dangerous section wear reaches  5% of the original size (the wear of a single laminated hook is ≥3%);

  • Cracks  or  plastic deformation occur in any part  .

5. Relationship with other standards

  • Compared with ISO : GB/T 10051.3 is equivalent to  ISO 3076 , but the fatigue test requirements are more stringent;

  • Special equipment specifications :  The additional requirements of TSG Q0002-2023 "Technical Safety Regulations for Hoisting Machinery" must be met at the same time  .

VI. Implementation suggestions for enterprises

  1. Selection and procurement :

    • Suppliers are required to provide  material report + flaw detection report + heat treatment record ;

    • Priority will be given to units that participated in the drafting of standards (such as Shanghai Zhenhua and Weihua Group).

  2. Quality Control :

    • Conduct hardness sampling before storage  (≥5% for each batch);

    • Use  a laser rangefinder  to monitor the deformation of the hook mouth.

  3. Compliance Management :

    • Establish  a full life cycle archive of the hook (including test data and maintenance records);

    • Scrapped hooks must  be physically destroyed  to prevent misuse.

7. Common Non-Conformities

  • Material substitution : using non-standard steel from small steel mills to impersonate 34CrMo;

  • Missed flaw detection : Only MT is performed without UT, and internal defects are ignored;

  • Refurbishment abuse : Secondary use after privately welding to repair cracks.

Summary : GB/T 10051 ensures hook safety through full-process specifications for materials, processes, and testing. Companies need to combine TSG Q0002 with actual working conditions to develop stricter internal control standards (e.g., tightening the scrap wear limit from 5% to 3%).

The following is a detailed interpretation of the Chinese national standard  GB/T 10051 "Lifting Hooks"  , covering the core content, technical points and practical application guidance:

1. Standard Architecture

GB/T 10051 is a series of standards, including the following parts:

  • GB/T 10051.1 : Mechanical properties, lifting capacity, stress and materials of lifting hooks

  • GB/T 10051.2 : Technical requirements for straight handle lifting hooks

  • GB/T 10051.3 : Technical requirements for forged lifting hooks

  • GB/T 10051.4 : Inspection of the use of straight handle lifting hooks

  • GB/T 10051.5 : Technical requirements for stacked hooks for lifting hooks

2. Core Technology Requirements

1.  Material requirements (GB/T 10051.1)

  • Material Grade :

    • Forged hooks: must be made of  high-quality alloy steel (such as 34CrMo, 34CrNiMo6), with sulfur and phosphorus content ≤ 0.035%;

    • Laminated hook: The steel plate must comply with Q690D and above in GB/T 1591.

  • Mechanical properties :

    index Forged Hook Requirements Laminated hook requirements
    tensile strength ≥785 MPa ≥690 MPa
    Yield Strength ≥590 MPa ≥550 MPa
    Elongation ≥15% ≥16%

2.  Manufacturing process (GB/T 10051.3)

  • Forging process :

    • Die forging  or  free forging + finishing must be used  , casting is prohibited;

    • The thread accuracy of the hook handle must reach  6g level (GB/T 197).

  • Heat Treatment :

    • After quenching and tempering (quenching + tempering), hardness range is  HB 207~255 ;

    • 100% hardness gradient test is required  , and the hardness difference of the same hook body is ≤15HB.

3.  Safety factor and load (GB/T 10051.1)

  • Design safety factor :

    • Static load safety factor ≥4.0 (4 times the rated load);

    • Fatigue safety factor ≥1.8 (based on 100,000 cycles of loading).

  • Test load :

    Test Type Load requirements Eligibility criteria
    Factory test 1.25 times rated load No permanent deformation
    Type test 2.0 times rated load No cracks

3. Inspection and Acceptance

1.  Nondestructive testing (GB/T 10051.3)

  • NDT requirements :

    • 100% magnetic particle testing (MT) : hook surface crack detection (sensitivity A1 test piece);

    • Ultrasonic flaw detection (UT) : internal defect detection (Φ2mm flat bottom hole equivalent).

  • Defect determination :

    • Cracks and white spots: directly scrapped;

    • Single pore ≤Φ1.5mm (depth ≤3mm).

2.  Dimensional tolerance (GB/T 10051.2)

  • Hook width deviation: ±1% rated opening size;

  • Hook handle straightness: ≤0.5mm/100mm.

IV. Usage and scrapping standards (GB/T 10051.4)

1.  Regular inspection

  • Daily inspection : cracks on the hook surface and wear on the hook mouth;

  • Annual comprehensive inspection : including UT re-inspection and load test.

2.  Compulsory scrapping conditions

  • The hook mouth is deformed by more than 10% of its original size  ;

  • The dangerous section wear reaches  5% of the original size (the wear of a single laminated hook is ≥3%);

  • Cracks  or  plastic deformation occur in any part  .

5. Relationship with other standards

  • Compared with ISO : GB/T 10051.3 is equivalent to  ISO 3076 , but the fatigue test requirements are more stringent;

  • Special equipment specifications :  The additional requirements of TSG Q0002-2023 "Technical Safety Regulations for Hoisting Machinery" must be met at the same time  .

VI. Implementation suggestions for enterprises

  1. Selection and procurement :

    • Suppliers are required to provide  material report + flaw detection report + heat treatment record ;

    • Priority will be given to units that participated in the drafting of standards (such as Shanghai Zhenhua and Weihua Group).

  2. Quality Control :

    • Conduct hardness sampling before storage  (≥5% for each batch);

    • Use  a laser rangefinder  to monitor the deformation of the hook mouth.

  3. Compliance Management :

    • Establish  a full life cycle archive of the hook (including test data and maintenance records);

    • Scrapped hooks must  be physically destroyed  to prevent misuse.

7. Common Non-Conformities

  • Material substitution : using non-standard steel from small steel mills to impersonate 34CrMo;

  • Missed flaw detection : Only MT is performed without UT, and internal defects are ignored;

  • Refurbishment abuse : Secondary use after privately welding to repair cracks.

Summary : GB/T 10051 ensures hook safety through full-process specifications for materials, processes, and testing. Companies need to combine TSG Q0002 with actual working conditions to develop stricter internal control standards (e.g., tightening the scrap wear limit from 5% to 3%).

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