Hot-Dip Galvanized PH-Type Extension Ring
The PH-type extension ring is a general-purpose connecting fitting used in overhead transmission and distribution-line hardware assemblies. Its closed oblong structure provides an articulated connection and increases the distance between adjacent components in an insulator string or line-hardware assembly.
The extension ring can be installed between compatible fittings such as ball eyes, socket clevises, shackles, suspension clamps, tension clamps and tower attachment fittings. Its dimensions and mechanical load class must match the complete hardware string design.
The product shown includes PH-7 and PH-10 models. Additional PH-series sizes can be manufactured according to the approved drawing, required coupling dimensions and specified mechanical load.
Key Features
- Closed oblong-ring structure for overhead-line hardware connections
- Designed to extend the effective length of a fitting or insulator-string assembly
- Compact construction with no removable pins or threaded components
- Compatible with appropriately sized clevis, eye and socket fittings
- Carbon-steel construction for mechanical load transmission
- Hot-dip galvanized surface for outdoor corrosion protection
- PH-7 and PH-10 models shown in the product photographs
- Additional load classes and dimensions available to order
Typical Product Specifications
| Product Name | PH-Type Extension Ring |
|---|---|
| Alternative Names | Extension Link / Oval Link / Chain Link Fitting |
| Models Shown | PH-7 and PH-10 |
| Structure | Closed oblong ring |
| Base Material | Carbon steel, subject to the approved material specification |
| Manufacturing Method | Forged or formed and welded, depending on the approved model |
| Surface Finish | Hot-dip galvanized |
| Application | Overhead-line insulator strings and connecting-hardware assemblies |
| Connection Type | Eye-to-eye articulated connection |
| Installation | Installed with compatible clevis, eye, socket or shackle fittings |
| Customization | Model, length, bar diameter, opening size, load class, coating and marking |
Representative PH-Series Selection Data
| Model | Representative Length | Representative Load Class |
|---|---|---|
| PH-7 | 80 mm | 70 kN |
| PH-10 | 100 mm | 100 kN |
| PH-12 | 120 mm | 120 kN |
| PH-16 | 140 mm | 160 kN |
| PH-21 | 160 mm | 210 kN |
| PH-25 | 160 mm | 250 kN |
| PH-30 | 180 mm | 300 kN |
The values above are representative PH-series selection data and must not be treated as guaranteed values for the photographed products. Final dimensions, mass and specified failure load must be confirmed using the approved drawing and mechanical test report.
Applications
- Suspension insulator-string assemblies
- Tension insulator-string assemblies
- Connection between clamps and insulator strings
- Connection between insulator hardware and crossarm fittings
- Overhead ground-wire hardware assemblies
- Transmission and distribution-line connection systems
- Substation connection assemblies where compatible fittings are specified
Material and Manufacturing
The PH extension ring is normally manufactured from load-bearing carbon steel. Depending on the product model and manufacturing specification, the ring may be produced by integral forging or by forming and welding a steel section into a closed oblong shape.
The manufacturing route must be confirmed before publication because a product photograph alone cannot reliably distinguish a whole-forged ring from a welded ring. Material grade, heat treatment and welding requirements should follow the approved technical drawing.
Hot-Dip Galvanized Finish
The steel surface is hot-dip galvanized to improve corrosion resistance in outdoor overhead-line environments. Galvanizing requirements may be specified according to ISO 1461, GB/T 13912 or the applicable utility specification.
Coating thickness, surface condition and adhesion should be verified according to the purchase specification. Local zinc accumulation, minor color variation and the natural crystalline appearance of hot-dip galvanizing are not equivalent to structural defects.
Selection Guidance
- Confirm the required specified failure load of the complete hardware string.
- Select a PH model with compatible opening and bar dimensions.
- Check that the adjoining fittings can rotate without interference.
- Verify the required extension length and hardware-string geometry.
- Confirm the steel grade and manufacturing method.
- Specify the galvanizing standard and minimum coating requirement.
- Use the approved project drawing rather than selecting by model name alone.
Quality Inspection
- Raw-material certificate verification
- Model marking and dimensional inspection
- Surface inspection for cracks, laps and harmful deformation
- Weld inspection when a welded construction is used
- Hot-dip galvanized coating appearance and thickness inspection
- Mechanical specified-failure-load testing when required
- Assembly compatibility inspection with adjoining fittings
- Final marking, quantity and packaging inspection
Reference Standards
- IEC 61284 – Overhead lines: requirements and tests for fittings
- GB/T 2315-2017 – Specified failure load series and coupling dimensions for electric power fittings
- ISO 1461:2022 – Hot-dip galvanized coatings on fabricated iron and steel articles
- GB/T 13912 – Hot-dip galvanized coatings on fabricated iron and steel articles
- Applicable utility drawings and project technical specifications
Reference to a standard does not constitute certification. Compliance must be supported by inspection or test documentation for the exact product model supplied.
Ordering Information
Please provide the following information when requesting a quotation:
- Required model, such as PH-7 or PH-10
- Specified mechanical failure load
- Overall length and internal opening dimensions
- Steel material and manufacturing method
- Hot-dip galvanizing standard and coating requirement
- Models and dimensions of the adjoining fittings
- Applicable standard or approved project drawing
- Required test reports and inspection certificates
- Order quantity, marking and packaging requirements
Frequently Asked Questions
What is a PH extension ring used for?
It is used to connect and extend overhead-line hardware assemblies, including insulator strings, clamps and tower-side connection fittings.
What do PH-7 and PH-10 mean?
They are model designations commonly associated with different dimensional and mechanical load classes. The required capacity must still be verified against the approved drawing and test report.
Is this product a lifting chain link?
No. It is an electric power line fitting intended for an approved overhead-line hardware assembly. It must not be advertised as general lifting or rigging hardware without separate certification for that use.
Is the extension ring forged?
Forged and formed-and-welded constructions are both available in the market. The exact manufacturing method must be confirmed for the supplied model.
Can customized dimensions be supplied?
Yes. Length, section diameter, internal opening, mechanical load class, coating and marking can be manufactured according to an approved drawing and agreed test requirements.
