Pre-Insulated Pipe Fittings DN20-1200

Overview

Why Factory Pre-Insulated Fittings Beat On-Site Insulation Every Time

The #1 source of heat loss in district heating networks is not the straight pipe — it is the junctions. Elbows, tees, and reducers represent concentrated points of thermal stress, mechanical load, and geometric complexity that make on-site insulation inherently unreliable. Factory pre-insulated fittings solve this problem by manufacturing the entire three-layer structure (carrier pipe, PU foam, HDPE casing) under controlled conditions. High-pressure PU injection fills every cavity and eliminates air pockets that manual foaming inevitably leaves behind. The result: pre-insulated fittings that match straight pipe thermal performance, deliver 100% void-free insulation at every junction, and eliminate the thermal bridges that degrade network efficiency.

◆ High-Pressure PU Injection — Zero Air Pockets. On-site manual foaming cannot achieve the density and uniformity of factory high-pressure injection. Our pre-insulated fittings are foamed at pressures that force PU into every corner of the fitting geometry — around bends, into tee branches, and through reducer transitions. The result is ≥60 kg/m³ density throughout the pre-insulated fitting, with no voids that would create heat loss hot spots in field-foamed junctions.

◆ Corona + Sandblasting — Unbreakable Three-Layer Bond. Every pre-insulated fitting undergoes the same surface preparation as our straight pipes: the steel carrier pipe is sandblasted (Sa2.5), and the HDPE casing inner surface receives corona treatment. The PU foam bonds chemically and mechanically to both surfaces, creating a monolithic pre-insulated fitting that moves as a single unit under thermal expansion — no layer separation, no hidden corrosion paths.

◆ All Fitting Types — One Supplier, One Warranty. We manufacture the complete range of pre-insulated fittings: elbows (30°, 45°, 60°, 90°), equal and reduced tees (straight and side-outlet), and both concentric and eccentric reducers. DN20–1200mm. Having one supplier for straight pipes and all pre-insulated fittings simplifies procurement, ensures material compatibility, and provides a single warranty for your entire district heating network.

◆ Optional Alarm Wire Integration. Leak detection alarm wires can be pre-installed inside the insulation layer of pre-insulated fittings and connected directly to your network monitoring system. This provides the same real-time moisture detection at critical junctions that Swedish and German standard systems deliver on straight pipe sections — complete network visibility, no blind spots at fittings.

◆ EN 448 Certified — Fittings-Specific Standard. Our pre-insulated fittings are manufactured and tested to EN 448, the European standard for bonded single-pipe pipe-in-pipe fittings. This fittings-specific standard ensures the complex junction geometry is properly insulated, bonded, and sealed — certification that general pipe standards like EN 253 do not cover for fittings.

Factory Pre-Insulated Fittings vs. On-Site Foamed Junctions

Feature

Sanjie Pre-Insulated Fittings

On-Site Manual Foaming

PU Density

≥60 kg/m³ — uniform

Variable — typically 30–50 kg/m³

Air Pockets

Zero — high-pressure injection

Common — especially at bends

Thermal Bridges

None — 100% void-free fitting

Yes — at every unfilled cavity

Bonding

Steel: Sa2.5 + HDPE: corona treatment

Surface may be dirty/wet on site

Weather Dependency

None — factory environment

Rain/humidity degrade foam quality

Testing

100% factory pressure-tested before shipping

No standardized on-site test

Alarm Wire

Pre-installed in factory

Difficult to retrofit on-site

Certification

EN 448 (fittings-specific standard)

No applicable on-site standard

Service Life

30–50 years

Often fails early at improperly foamed junctions

Warranty

Single warranty for entire network

Split responsibility — difficult claims

Technical Specifications

Parameter	Standard / Value
Fitting Types	Elbow (30°/45°/60°/90°), Equal Tee, Reduced Tee, Concentric Reducer, Eccentric Reducer
Structure	Carrier Pipe + Rigid PU Foam (≥60 kg/m³) + HDPE Outer Casing
Carrier Pipe Options	Carbon Steel (seamless/welded), Stainless Steel, HDPE, PPR
Diameter Range	DN20–1200mm
Pressure Rating	≤2.5 MPa (steel carrier); lower for plastic carriers
Operating Temperature	−50°C to 120°C continuous (140°C peak)
PU Density	≥60 kg/m³ per EN 448
Service Life	30–50 years
Standards	EN 448 / ISO 9001
Certifications	ISO 9001 / CE
Packaging	Individual weather-resistant wrapping with end caps

Application Scenarios

District Heating & Cooling Junction Points. Pre-insulated elbows, tees, and reducers eliminate thermal bridges at every direction change, branch-off, and diameter transition in your network. EN 448 certified factory foaming ensures thermal continuity at the most critical points.

Oil & Gas Temperature Maintenance. Stainless steel carrier pre-insulated fittings for corrosive fluids and high-temperature applications. Same 100% void-free PU insulation ensures hot oil viscosity maintenance through every fitting in the pipeline.

Industrial Process Flow Transitions. Concentric and eccentric pre-insulated reducers maintain insulation integrity across diameter changes. Critical for industrial heating and cooling systems where every degree of temperature loss at a reducer translates directly to process cost.

Trusted Across 110+ Countries

Our pre-insulated fittings serve district heating operators, EPC contractors, and industrial plant managers worldwide. Complete your insulated pipe system with EN 448 certified factory fittings from the same manufacturer.

Service & Support

From fitting type selection through joint welding to network commissioning, our team supports your entire pre-insulated fitting system project.

Service Item	Details
Pre-Sales Consulting	Fitting type selection (elbow angle, tee orientation, reducer type), carrier pipe material recommendation.
Engineering Design	CAD/PDF with fitting layout, thermal expansion compensation design, alarm wire routing.
Free Samples	At no charge. Customer covers freight. EN 448 foam density and bond strength test certificates included.
Production & QC	ISO-certified. 100% factory pressure-tested. Foam density and void-content verified per EN 448.
Delivery	7–14 days. EXW, FOB, CIF. Individual protective packaging for each pre-insulated fitting.
MOQ	Flexible per project scope.
Technical Support	Joint welding supervision, fitting installation guidance, alarm wire connection and commissioning.
After-Sales Warranty	30–50 year comprehensive warranty. Dedicated team for technical support.
Payment Terms	T/T, L/C at sight. Flexible for long-term partners.
OEM / ODM	Custom fitting type, diameter, carrier material, and alarm wire configuration available.