ALL PRODUCTS

Prefab Direct Buried Insulated Pipe DN20-1600 | EN 253 District Heating Pipeline

Prefab Direct Buried Insulated Pipe DN20-1600 | EN 253 District Heating Pipeline

Drafters of 8 national standards including GB/T 29047 & GB/T 34611. Steel-PU-HDPE, 0.033 W/m·K, DN20–1600mm, 30–50 year life. National High-Tech Enterprise, 530,000 m² factory, 110+ countries. Request free sample & quote!

Overview
Technical Specifications
Application Scenarios
Service & Support
Recommended Products

Overview

Why Choose Sanjie Direct Buried Insulated Pipe?

EN 253 direct-buried systems are now the international standard, replacing traditional trench-and-wrap methods that lose 30–50% of thermal energy before reaching end users. Sanjie has been at the center of this transition for 28 years.

◆ We Drafted the Standards That Define This Industry. Sanjie is a drafting unit for GB/T 29047-2021 and GB/T 34611-2017. National High-Tech Enterprise with 80+ patents across 530,000 m² and 3 industrial bases (Luoyang, Cangzhou, Lanzhou). When you buy from Sanjie, you buy from the company that wrote the rulebook.

◆ 0.033 W/(m·K) — 75% Lower Heat Loss. Rigid PU foam (≥60 kg/m³) with closed-cell structure delivers void-free insulation. Over a 25-year lifecycle, energy savings from a single kilometer can offset the entire initial purchase cost — after which the pipe delivers decades of pure operational savings.

◆ Spraying & Winding Process — Stronger Bond. Proprietary process applies PU foam in controlled layers, creating a rough interlocking interface with the HDPE jacket. Combined with online corona treatment of the HDPE inner surface, this eliminates the delamination failure mode that plagues single-shot foaming.

◆ 7 Automated Lines — Full In-House QC. DN1400 automated line, DN1600 foaming line, PE2200 and PE2000 jacket extrusion — every layer produced in-house. Steel pipe Sa2.5 blast-cleaned to GB/T 8923.1 before foaming for maximum bond strength.

◆ 4-Step Certified Joint Process. (1) HDPE sleeve positioning, (2) heat-shrink tape wrapping, (3) pneumatic tightness test at 0.02 MPa, (4) PU foam injection with knock-test verification. Joints match factory pipe in thermal and waterproof integrity.

Sanjie Pre-Insulated vs. Traditional Trench-and-Wrap

Feature	Sanjie Pre-Insulated	Traditional Trench & Wrap
Thermal Conductivity	0.033 W/(m·K) — factory-tested	0.05–0.08 W/(m·K) — variable
Heat Loss	25% of traditional pipe	100% (baseline)
Insulation Life	30–50 years (sealed)	Degrades as moisture enters
Corrosion Protection	HDPE jacket + PU barrier	Exposed once wrap fails
Installation	Pre-fabricated — lay, join, bury	On-site wrapping — weather-dependent
Leak Detection	Fiber optic monitoring option	None — dig when it fails
Standards	EN 253 / GB/T 29047 (we drafted)	No uniform standard
Lifecycle Cost	10–25% lower over 30 years	Lower upfront, higher operating

Technical Specifications

Parameter	Standard / Value
Working Pipe	Seamless / Spiral Welded / ERW Steel (Sa2.5 per GB/T 8923.1)
Insulation	Rigid PU Foam — density ≥60 kg/m³, ≤0.033 W/(m·K)
Outer Jacket	HDPE (≥PE80) with corona treatment
Diameter Range	DN20–1600mm (steel up to 1620×20mm, jacket up to 1890×20mm)
Operating Temperature	−50°C to 120°C (peak ≤130°C)
Medium Pressure	≤2.5 MPa
Service Life	30–50 years (EN 253 certified)
Standards	GB/T 29047 / GB/T 34611 (drafted by Sanjie) / EN 253
Certifications	ISO 9001 / ISO 14001 / ISO 45001 / CE
Joint Process	4-step: sleeve → heat-shrink → 0.02 MPa test → PU fill
Smart Monitoring	Optional fiber optic + GPRS/CDMA/WiFi + trend analysis
Fittings	Tee / Elbow / Reducer / Fixed bracket
Packaging	End caps + weather-resistant bundling

Application Scenarios

Urban District Heating Primary Networks. DN200–1600mm for municipal heating backbones. Direct-buried under roads — no concrete trenches. HDPE jacket is 100% waterproof. EN 253 certified 30–50 year design life.

District Cooling & Industrial Chilled Water. PU insulation works both ways — blocking heat gain in data center HVAC, airport terminals, and food processing. Same 0.033 W/(m·K) performance in both directions.

Cold Climate & Permafrost. Rated to −50°C. PU insulation prevents frost heave around the pipe. Bonded three-layer structure flexes with ground movement through 100+ freeze-thaw cycles per year.

Smart City Leak Detection. Embedded fiber optic sensing for real-time monitoring. Moisture detected and located to the meter before corrosion begins. Wireless data feeds SCADA or standalone HMI.

Long-Distance Heat Transmission. For 10–50 km runs from plant to city. Every 0.01 W/(m·K) matters. Sanjie's 0.033 at DN1200+ scale keeps delivery temperature within spec across the longest distances.

Trusted Across 110+ Countries

Our insulated pipes serve district heating operators, municipal governments, EPC contractors, and industrial facilities worldwide. As drafters of GB/T 29047, we deliver engineering authority, not just pipes. EN 253 compliance documentation and project references available on request.

Service & Support

Full-Process Service — Engineering to Lifetime Operation

Service Item	Details
Pre-Sales Consulting	Heat loss calculation, burial depth analysis, insulation thickness selection, steel grade recommendation.
Engineering Design	CAD/PDF drawings with thermal calculations, expansion loops, fixed bracket positioning, monitoring integration.
Free Samples	At no charge. Customer covers freight. Cross-section sample for bond and density verification.
Production & QC	Up to DN1600 on automated lines. EN 253/GB/T 29047 tested. Regular progress and QC reports.
Delivery	7–14 days. EXW, FOB, CIF. Container-optimized with full accessory kit.
MOQ	Flexible per project scope.
Technical Support	Joint sealing training, air-tightness testing, smart monitoring commissioning, thermal expansion design.
After-Sales Warranty	Comprehensive warranty. Dedicated support team for installation, maintenance, and technical inquiries.
Payment Terms	T/T, L/C at sight. Flexible for long-term partners.
OEM / ODM	Custom branding, marking, packaging, specification available.