Safety maintenance knowledge of lifting equipment hooks

Introduction to the hook

The classification of hooks is extremely broad, generally including shackles, lifting rings, plate hooks, forged hooks, round rings, pear-shaped rings, lifting rings, combined lifting rings, S-shaped hooks, nose hooks, American-style hooks, horn hooks, eye-shaped sliding hooks, lifting ring screws with safety cards, chain shackles, etc. Now, the following three types are mainly introduced:

Plate type hook

Plate hooks are divided into single hooks and double hooks. They are generally made by riveting multiple pieces of C3 and 16Mn steel plates together. This type of hook has a simple structure, reliable operation and is easy to maintain. Single hooks are mostly used in casting cranes, while double hooks are mostly used in general-purpose cranes with a capacity of over 100 tons.

Forged hook

Forged hooks are divided into two types: single hooks and double hooks. It is generally forged as a whole from 20 and 20MnSi steel. Due to the eccentricity of a single hook, its force application is not as favorable as the symmetrical force application of a double hook. Therefore, cranes with medium and small tonnage under 75 tons mostly use single hooks, while those with large tonnage over 75 tons mostly use double hooks. This type of hook is widely used and has formed a series. When there is a risk of the steel wire rope coming off the hook, a safety hook is installed.

Lifting ring

The lifting ring has an advantage over the hook in terms of force application. When the lifting capacity is the same, its self-weight is lighter, but it is not as convenient to use as the hook. Therefore, the use of the lifting ring is far less widespread than that of the hook. It is mainly used on cranes that operate frequently and have a large lifting capacity. Its structure is divided into integral type and articulated type, with the latter being more commonly used.

The reasons for the fall of lifting hook objects

The fall of the hook object can pose a significant safety hazard to people's personal safety. Before and during the operation, any factors that may affect the safety of the hook should be noted

1. The non-standard hook

1.1 Risks brought about by non-standard design, such as failure of overload protection and unreasonable selection of lifting gear and rigging, etc.

1.2 Manufacturing defects and installation defects, etc., have led to the use of equipment with potential risks.

2. Unsafe human behavior

2.1 It is manifested as unproficient operational skills and a lack of necessary safety education and training.

2.2 Working without a license;

2.3 Acting in violation of regulations and discipline, and bad operating habits;

2.4 Judging operational errors and unclear command signals.

3. Environmental factors

3.1 In environments that exceed safety limits or hygiene standards, such as those with high dust, high temperature, high humidity, low temperature, high noise, strong wind, or poor lighting, conducting lifting operations will distract attention, directly affecting the reaction ability and stability of technical performance of the operators, increasing the chances of misoperation and violation of regulations, and leading to accidents.

3.2 Poor working conditions can also lead to a decline in the functionality of the crane system itself and even accelerate the failure of components, becoming one of the unsafe factors.

4. Deficiencies in safety management

4.1 Lack of management, inspection and regular safety performance testing of cranes;

4.2 Lack of safety education and training for relevant personnel, formulation of crane safety operation regulations, establishment of violation reward and punishment systems, and accident emergency response plans;

4.3 Lack of regular inspection of lifting equipment and auxiliary lifting tools, lack of effective monitoring and management, etc.

In conclusion, strengthening safety education and training for personnel related to cranes and conducting regular safety performance inspections and tests on in-use cranes (including lifting accessories) are necessary guarantees for reducing the occurrence of accidents caused by the fall of objects lifted by crane hooks.

Daily maintenance of hooks

The elimination of potential safety hazards of hooks requires maintenance, which is indispensable. Daily inspection and maintenance include the following contents:

1. Wipe the main hook clean;

2. Lubricate pulleys, rotating parts and other parts with grease nipples;

3. Check all bolts and screws to ensure that all cotter pins are complete and the openings are fully opened.

4. Check whether the wear of the pulley groove and rim is uniform, whether the steel wire rope matches the groove, and whether the pulley is loose or shaking

5. Ensure that the rotating part of the hook rotates freely and the clearance is not too large. If the rotation is difficult or there is a feeling of being stuck, it is necessary to check whether the bearing or bushing is damaged or the lubrication is insufficient.

6. Check for overload damage to the main hook;

7. Check for side plate elongation, hole diameter elongation, bolt bending or elongation, cracks, etc.

8. Check the anti-disengagement device.

Carry out daily maintenance of the hook to eliminate potential hazards in their infancy. This is not only responsible for the progress of the project, but also for the lives and property of the construction workers.

Check the hook bodies of each hook

The hook body of the hook should be inspected at least once a year, using dye penetrant testing, magnetic particle testing, ultrasonic testing or X-ray testing, etc. Check whether the hook is deformed, has local cold deformation, or has claws squeezed, cracked, worn or rusted. Lock the joint of the hook nut.

Deformation: If the hook claw has increased by more than 10% compared to the original size, the hook must be replaced. The original dimensions are recorded on the hook. Measure each one individually.

Corrosion: It is necessary to check whether there is corrosion and wear on the threads and the operated shaft. For this purpose, the hook nut on the shaft must be loosened.

If further processing is required to remove corrosion, the process must not cause the diameter of the threaded core to exceed 5%; otherwise, the hook must be replaced. Failing to replace scrapped parts in a timely manner and lacking necessary safety protection and maintenance is irresponsible to oneself.

It should be scrapped when the following circumstances occur

The opening degree of the crane hook is larger than the original size.

2. Cracks;

3. The wear of the dangerous section reaches 10% of the original size.

4. The opening degree is 15% higher than the original size.

5. Torsional deformation exceeds 10°;

6. Plastic deformation occurs at the dangerous section or the neck of the hook;

When the wear of the plate hook bushing reaches 5% of its original size, the bushing should be scrapped.

When the wear of the core shaft of the plate hook reaches 5% of its original size, the core shaft should be scrapped.

9. It is found that the hook welding repair and other hooks are subject to high temperature, strong corrosion or exceed the enterprise's regulations, etc.

10. Defective hooks must not be used, and hooks must not be repaired by welding.