QT700 Double-Layer Electric Manhole Cover, consisting of an outer load-bearing main cover, an inner protective secondary cover, and a manhole frame. It is made of QT700-2 pearlitic ductile cast iron. The double-layer structure is a dedicated design for electrical manholes: the outer cover bears vehicle loads from the road surface, while the inner cover provides fall protection, isolation, dust prevention, and stops debris from falling into the cable pit, preventing accidental falls of personnel and protecting internal cables, terminals and joints.
Also known as a parent-and-child cover, the manhole frame is generally fitted with a rubber shock-absorbing sealing gasket. Anti-theft locks and hinges can be installed. It is the mainstream heavy-duty manhole cover for cable pits in municipal power grids and distribution network projects.
1.QT-700 Material
Conforms to GB/T 1348-2019 standard (QT700-2 grade), tensile strength >=700MPa, elongation >=2%, HB180-220, impact toughness at -40℃ >=27J, possessing high strength, wear resistance, and impact resistance.
2. Double-Layer Structure
QT-700 one-piece molding (thickness >=15mm), anti-slip serrations (depth >=1.5mm), bearing load protection;
Optional fiberglass/rubber/carbon steel, focusing on sealing, insulation, and heat preservation, forming a sealed space with the upper layer.
Load-bearing safety: D400 load capacity (40 tons), lower insulation resistance >=10¹²Ω, leak-proof;
A rubber sealing ring is installed between the double-layer cover, combined with an embedded structure, achieving IP67 waterproof and dustproof rating, blocking rainwater, sewage, and harmful gases (such as hydrogen sulfide) from intrusion, protecting the cable from corrosion;
Anti-theft and security:
Integrated three-point concealed lock, special bolt or hinge fixing device, requires a special T-key to open, some models can be customized with a GPS tracking module, the theft rate is close to zero;
The surface adopts a "zinc-based alloy + epoxy resin" double-layer coating (thickness >=80μm), passing a 500-hour salt spray test without rust, adaptable to harsh environments such as coastal saline-alkali land and northern freeze-thaw cycles.
Urban municipal high-voltage / low-voltage power cable inspection wells, cable branch wells, and ring main unit (RMU) foundation wells.
Power wells for main carriageways, urban》roads and heavy-load roads in industrial parks (Class D400 / E600).
Cable passages and cable trench openings for residential communities, industrial parks and substations.
Power pipeline wells in heavy-duty areas such as airports, ports and industrial zones.
Double-layer mother-child structure: the outer cover bears traffic loads, while the inner cover provides independent protection. During maintenance, only the inner cover can be opened without moving the heavy outer cover for convenient inspection and repair.
Superior safety performance: The inner cover functions as an anti-fall barrier. Even if the outer cover is accidentally missing, the inner cover can still prevent personnel from falling and protect the underground cable equipment.
The QT700 double-layer electrical manhole cover offers dustproof and waterproof performance. Its double-layer structure combined with sealing rubber rings can greatly reduce the inflow of rainwater and sediment into the cable well, lowering the risks of cable dampness and silt accumulation in the well.
| QT700 Double-Layer Electric Manhole Cover | |
| >=700 MPa | |
| >=420 MPa | |
| >=2% | |
| 225-305 HBS | |
| >=80% | |
| >=Grade 3 | |
| Φ700 mm | |
| Φ800 mm | |
| Double-layer (outer main cover + inner sub cover + manhole frame) | |
| Surface anti-corrosion treatment | Anti-corrosion with black asphalt spraying |
| Nitrile rubber shock-absorbing sealing ring | |
| Anti-theft lock, safety hinge; anti-fall chain (optional) | |
| GB/T 1348 Ductile Iron Castings, GB/T 23858 Inspection Manhole Covers, EN 124 |
C30 concrete base (>=150mm), layered installation (gap <=3mm), flatness error <=2mm, no leakage after 30 minutes of water injection;
Quarterly inspection of locks/coatings, cleaning with neutral detergent, replacement of cracks/deformation, welding repair is prohibited.
With superior product quality and mature export delivery capacity, our products have been exported to many countries including the United Kingdom, Brazil, Mexico and Spain. They operate steadily over the long term in various engineering projects with no major quality failures or acceptance disputes. We offer full-range customization, including non-standard sizes, special wall thickness, custom coatings and customer-specified markings. For wholesale buyers, we adopt tiered pricing based on product specifications, purchase quantities and coating options. Simply share your product parameters and purchase volume to get your exclusive wholesale quotation. Consistent reliable performance and excellent cost-effectiveness bring us repeat orders from domestic and global customers, making us a trusted preferred supplier for overseas wholesalers.
Shanxi Jintai Hongye Casting and Forging Machinery Co., Ltd., located in Shanxi Province, China, is a leading manufacturer of ductile iron pipe fittings, pipes, various valves, and manhole covers. We have automated production lines and an experienced production technology team to provide you with professional and flexible customized solutions.
+8618334738900
info@jthypipe.com, amy@jintaicastfoundry.com, sales@jintaicastfoundry.com
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