Un anneau en D de levage à souder est un point de levage résistant à la charge conçu pour être soudé sur des machines., structures en acier, cadres de levage, équipement offshore, châssis de transport, et autres composants porteurs.
Typiquement, the assembly consists of a forged lifting ring and a weld-on mounting block. Selon la conception, the lifting ring may pivot within one plane or accommodate loads from several specified directions.
Pendant le levage, the load transfer through the following path:
Fronde / Manille / Hook → D-Ring → Weld-On Block → Weld → Supporting Structure
Cependant, WLL represents only one part of the lifting system. Donc, engineers and buyers should also consider load direction, angle d'élingue, supporting structure, soudage, connection geometry, matériel, essai, et inspection.
Table des matières
- Design and Construction
- Applications typiques
- Espèces, Materials and Load Ratings
- How to Select a Weld-On Lifting D-Ring
- Welding and Installation
- Fabrication, Testing and Traceability
- Inspection and Removal Criteria
- What Buyers Should Compare
- Questions fréquemment posées
- Conclusion
1. Design and Construction
A Weld-On Lifting D-Ring normally contains the following components:
| Composant | Fonction |
|---|---|
| Forged lifting ring | Carries the lifting load and connects to shackles, crochets, or slings |
| Weld-on block | Transfers the load into the supporting structure |
| Pivoting connection | Allows movement within the permitted loading direction |
| WLL marking | Identifies the rated working load |
| Traceability marking | Links the product to manufacturing and inspection records |
Manufacturers commonly produce the lifting ring from forged and heat-treated alloy steel. The material and heat treatment determine strength, dureté, deformation resistance, and fatigue performance. En outre, the weld-on block must provide sufficient mechanical strength while maintaining suitable weldability.
Load Path
Pour cette raison, engineers should evaluate the lifting point as part of the complete load path rather than as an isolated component.
A lifting point may incorrectly applied if:
- The supporting plate is too thin
- The supporting steel has insufficient strength
- The weld size is inadequate
- The weld contains defects
- The lifting point install in the wrong orientation
- The applied load direction is not permitted
- The connected hook or shackle causes point loading
- The load distributed unevenly
Donc, the lifting point, weld, supporting structure, and rigging arrangement must considered together.
Lifting D-Ring vs. Lashing D-Ring
| Lifting D-Ring | Lashing D-Ring |
|---|---|
| Intended for lifting suspended loads | Intended mainly for cargo restraint |
| Rated by WLL | Commonly rated by lashing capacity |
| Connected to lifting slings, chaînes, ou des crochets | Used for cargo securing |
| Designed and tested for lifting applications | May follow different design requirements |
2. Applications typiques
En pratique, weld-on lifting points are used where equipment requires a fixed lifting connection.
| Industrie | Applications typiques |
|---|---|
| Machinerie lourde | Générateurs, pompes, compressors, machine frames, interrupteur |
| Construction | Excavatrices, pièces jointes, earthmoving machinery |
| Exploitation minière | Broyeurs, drilling equipment, machinery frames |
| En mer & Marin | Offshore skids, deck equipment, modules, marine machinery |
| Steel Fabrication | Tanks, frames, poutres de levage, structural assemblies |
| Transport | Transport frames and handling equipment |
3. Espèces, Materials and Load Ratings
Types communs
| Taper | Caractéristiques | Application |
|---|---|---|
| Pivoting Weld-On D-Ring | Pivots within one plane and can usually fold down | Machinery and general lifting |
| Multi-Directional Lifting Point | Designed for several specified loading directions | Angular lifting and equipment rotation |
| Heavy-Duty Load Ring | Larger connection area and higher capacity | Heavy fabrication and offshore equipment |
| Spring-Retained Design | Ring remains in position when unloaded | Mobile and vibrating equipment |
| Special-Environment Design | Uses specific materials or surface protection | Marin, chimique, or low-temperature service |
Materials and Heat Treatment
The load-bearing ring commonly made from forged and heat-treated alloy steel. The material specification and heat treatment affect:
- Résistance à la traction
- Toughness
- Résistance à la fatigue
- Resistance to permanent deformation
- Performance during proof testing
WLL, Proof Load and Breaking Load
| Terme | Signification |
|---|---|
| CMU – Limite de charge de travail | Maximum permitted working load under specified conditions |
| Charge d'épreuve | Test load applied to verify product integrity |
| Charge de rupture minimale | Specified minimum load associated with destructive failure |
| Facteur de conception | Relationship between working capacity and design strength |
4. How to Select a Weld-On Lifting D-Ring
Selection should be based on the lifting arrangement and installation conditions.
| Facteur | Que vérifier |
|---|---|
| Poids de charge | Gross lifting weight |
| Center of Gravity | Répartition de la charge |
| Number of Lifting Points | Actual load on each point |
| Angle d'élingue | Increase in sling-leg tension |
| Loading Direction | Verticale, angular, side, or multi-directional |
| Supporting Structure | Steel grade, épaisseur, renforcement, weldability |
| Connection Dimensions | Compatibility with shackles, crochets, or slings |
| Environnement | Température, corrosion, marine or chemical exposure |
| Attestation | Essai, CND, traçabilité, third-party requirements |
5. Welding and Installation
The weld forms part of the load path and should be treated as a structural connection.
Installation Requirements
| Exigence | Consideration |
|---|---|
| Surface Preparation | Remove paint, rouiller, huile, scale, et contamination |
| Welding Procedure | Follow product and supporting-steel requirements |
| Weld Size | Meet the specified dimensions |
| Filler Material | Match the weld-on block and parent steel |
| Welder Qualification | Suitable for the process and material |
| Orientation | Match the specified loading direction |
| Clearance | Allow free movement of the lifting ring |
| Inspection | Verify the completed installation |
The welding procedure may also specify:
- Number of weld passes
- Welding sequence
- Preheat
- Interpass temperature
- Cooling requirements
- Inspection method
Load-Bearing Ring
The forged and heat-treated lifting ring should not be subjected to uncontrolled:
- Welding heat
- Heating
- Pliage
- Reshaping
- Grinding of load-bearing sections
Uncontrolled heating can change the material properties produced during heat treatment.
Welding should be limited to the components designed for welding.
Post-Weld Inspection
Selon l'application, inspection may include:
- Visual inspection
- Dimensional inspection
- Magnetic-particle testing
- Dye-penetrant testing
- Other specified NDT methods
The surrounding supporting structure should also be checked where required.
6. Fabrication, Testing and Traceability
The performance of a lifting point depends on manufacturing controls throughout production.
| Manufacturing Stage | Contrôle |
|---|---|
| Raw Material | Material grade and heat/batch traceability |
| Forgeage | Geometry and load-bearing sections |
| Traitement thermique | Force, dureté, and fatigue properties |
| Usinage | Dimensions and functional fit |
| CND | Crack and defect detection |
| Tests de preuve | Verification of load-bearing integrity |
| Marquage | WLL and traceability |
| Documentation | Inspection and test records |
Traçabilité
Product identification may include:
- WLL
- Identification du fabricant
- Product designation
- Batch number
- Heat number
- Serial number
- Certificate reference
This allows the product to be linked to its manufacturing records:
Material → Heat Treatment → Inspection → Testing → Certification
Traceability is commonly required for offshore, energy, exploitation minière, and other controlled lifting applications.
7. Inspection and Removal Criteria
Inspection should cover: D-Ring + Weld-On Block + Weld + Supporting Structure
Articles d'inspection
| Inspection Item | Concern |
|---|---|
| Cracks | Structural failure |
| Permanent deformation | Surcharge |
| Excessive wear | Reduced load-bearing section |
| Corrosion | Material loss |
| Weld damage | Loss of connection strength |
| Restricted movement | Incorrect articulation |
| Heat damage | Change in material properties |
| WLL marking | Product identification |
| Supporting steel | Cracking or deformation |
The lifting point should remove from service when:
- Cracks are found
- Permanent deformation is visible
- Significant material loss has occurred
- Weld damage is present
- Corrosion exceeds the acceptance criteria
- Ring movement is restricted
- Product identification cannot be confirmed
- Unauthorized heating or modification has occurred
A damaged forged lifting ring should not be welded, heated, bent, or reshaped unless an approved repair procedure is available.
Inspection intervals should reflect the frequency of use, environnement, and service conditions.
8. What Buyers Should Compare
Two lifting points with the same WLL are not necessarily equivalent.
| Evaluation Item | What to Compare |
|---|---|
| WLL | Capacity and permitted loading direction |
| Matériel | Steel grade and heat treatment |
| Facteur de conception | Rating basis |
| Tests de preuve | Test load and frequency |
| CND | Inspection method and scope |
| Loading Direction | Verticale, angular, side, or multi-directional |
| Soudage | Installation procedure and weld requirements |
| Traçabilité | Batch or individual identification |
| Environnement | Temperature and corrosion limits |
| Attestation | Standards and third-party requirements |
| Documentation | Drawings, certificats, and reports |
WLL and price alone do not establish technical equivalence. The product specification should include design, matériel, essai, soudage, inspection, et informations de traçabilité.
9. Questions fréquemment posées
1. What does WLL mean on a Weld-On Lifting D-Ring?
WLL means Working Load Limit. It is the maximum working load permitted under the conditions specified by the manufacturer. A WLL 20T marking does not mean that the lifting point can carry 20 tonnes under every loading condition.
2. Can a Weld-On Lifting D-Ring be welded onto any steel plate?
Non. The supporting steel must have sufficient strength, épaisseur, renforcement, and weldability to transmit the lifting forces.
3. What material is used for Weld-On Lifting D-Rings?
Load-bearing rings commonly manufactured from forged and heat-treated alloy steel. The weld-on block must also provide suitable weldability.
4. Is Grade 80 or Grade 100 requis?
Not necessarily.For Weld-On Lifting D-Rings, WLL, matériel, traitement thermique, facteur de conception, proof load, loading direction, and applicable standards provide more relevant information.
5. Who should install a Weld-On Lifting D-Ring?
Installation need to carry out by a qualified welder using an appropriate welding procedure and the manufacturer’s installation requirements.
6. What information is required when requesting a quotation?
| Information | Typical Requirement |
|---|---|
| CMU requise | 5T / 10T / 20T, etc.. |
| Quantité | Number of lifting points |
| Equipment Weight | Gross lifting weight |
| Loading Direction | Verticale / angular / multi-directional |
| Angle d'élingue | Where applicable |
| Supporting Steel | Material and plate thickness |
| Matériel de connexion | Manille / crochet / sling |
| Environnement | Indoor / Marin / offshore |
| Température | Minimum and maximum |
| Essai | Proof test / CND |
| Attestation | Project or third-party requirements |
For high-capacity, offshore, or critical lifting applications, an installation drawing or lifting arrangement drawing should be provided.
10. Conclusion
A Weld-On Lifting D-Ring transfers lifting forces from the rigging system into the equipment or supporting steel structure.
Its selection should consider: WLL + Loading Direction + Sling Geometry + Supporting Structure + Soudage + Matériel + Essai + Attestation
Two lifting points with the same WLL may have different materials, loading directions, design factors, testing requirements, welding instructions, or certification. The lifting point should select according to the actual load case and installation conditions rather than by WLL or physical size alone.
NTSC manufactures and supplies lifting and rigging products, including weld-on lifting points, pour industriel, Marin, offshore, construction, and material-handling applications.
