High Temperature Inner Heat Shrink Sleeve (HT110/120)
Carrier Pipe Corrosion Protection for Pre-Insulated Pipelines | Design Temperature 110°C–120°C
Product Overview
Our High Temperature Inner Heat Shrink Sleeve is a three-layer, heat-shrinkable field joint coating system engineered specifically for the carrier steel pipe in pre-insulated pipeline systems. Unlike the outer sleeve (typically rated to 65°C) that seals the insulation jacket, this inner sleeve is applied directly onto the welded steel joint and must withstand the full pipeline design temperature—110°C to 120°C—without degradation.
The system combines a liquid epoxy primer, a high-temperature hot-melt adhesive, and a radiation cross-linked polyolefin backing to restore the corrosion protection of the carrier pipe at the field joint, before the polyurethane foam insulation and outer casing are reconstructed. It is suitable for high-temperature service where standard 65–80°C inner sleeves are inadequate.
Configuration
| Parameter |
Specification |
| Product Type |
High-temperature inner heat shrink sleeve (3-layer) |
| Application Position |
Carrier pipe (steel layer) at field joint |
| Design Temperature |
110°C – 120°C |
| System Type |
Epoxy primer + hot-melt adhesive + cross-linked backing |
| Service |
Pre-insulated pipelines, buried and above-ground |
| Compatibility |
3LPE, 3LPP, FBE plant coatings |
System Construction
| Layer |
Component |
Function |
| First Layer |
Two-component liquid epoxy primer |
Bonds to blast-cleaned steel; provides primary corrosion barrier and cathodic disbondment resistance |
| Second Layer |
High-temperature hot-melt adhesive |
Bonds to the epoxy primer and adjacent plant coating; maintains shear strength at 110°C+ |
| Third Layer |
Radiation cross-linked PE/PP backing |
Mechanical protection, moisture barrier, thermal stability at elevated temperatures |
The epoxy primer is applied to the prepared steel surface, followed by installation of the heat-shrinkable sleeve. Heat application causes the backing to shrink and the adhesive to flow, forming a continuous bond to the steel and the adjacent plant coating.
Key Features & Benefits
| Feature |
Benefit |
| 110–120°C High-Temperature Rating |
Engineered for pipelines where the carrier pipe operates at temperatures that would degrade standard 65–80°C inner sleeves |
| Inner Sleeve Positioning |
Applied directly to the carrier pipe before foam and outer casing reconstruction—protects the most critical corrosion barrier |
| 3-Layer Construction |
Epoxy + adhesive + cross-linked backing reproduces the factory coating structure for monolithic corrosion protection |
| High-Temperature Adhesive |
Maintains lap shear strength and peel adhesion at design temperature |
| Cross-Linked Backing |
Provides thermal stability and mechanical protection at elevated service temperatures |
| Compatibility with Outer Sleeve System |
Designed to work in conjunction with the 65°C-rated outer heat shrink sleeve that seals the insulation jacket |
Typical Performance Properties (Reference)
| Property |
Test Reference |
Typical Value |
| Backing Tensile Strength |
ASTM D638 |
≥ 21 MPa |
| Backing Elongation |
ASTM D638 |
≥500% |
| Backing Hardness |
ASTM D2240 |
50–60 Shore D |
| Adhesive Softening Point |
ASTM E28 |
≥ 110°C |
| Lap Shear at 23°C |
EN 12068 |
≥ 30 N/cm² |
| Lap Shear at 110°C |
EN 12068 |
≥ 2.75 N/cm² |
| Peel Strength to Steel (23°C) |
ISO 21809-3 |
≥ 5 N/mm |
| Peel Strength to Steel (110°C) |
ISO 21809-3 |
≥ 1.5 N/mm |
| Cathodic Disbondment (110°C, 28 days) |
ISO 21809-3 |
≤ 10 mm radius |
| Indentation Resistance (110°C) |
ISO 21809-3 |
Pass |
Reference values are drawn from comparable high-temperature heat shrink sleeve systems qualified to ISO 21809-3. Confirm final values against the CNPetro product data sheet.
System Context: Pre-Insulated Pipeline Field Joint
In a pre-insulated pipeline, the field joint involves two distinct sealing functions:
| Layer (from steel outward) |
Function |
Temperature Requirement |
| Carrier pipe corrosion protection |
Protects steel weld from corrosion |
110–120°C (this product) |
| Polyurethane insulation |
Thermal barrier |
Applied as foam; resists in-fill temperatures |
| Outer casing sealing |
Mechanical protection, moisture barrier |
65°C (standard outer heat shrink sleeve) |
The inner sleeve is applied first, directly over the welded and prepared steel joint. Once the inner sleeve is installed and inspected, the insulation cavity is filled with polyurethane foam, and the outer sleeve is installed to seal the casing jacket. The inner sleeve bears the full pipeline design temperature, while the outer sleeve operates at the lower temperature of the casing environment.
Compliance
Heat-shrinkable sleeves for pipeline field joint coatings are addressed under ISO 21809-3, which specifies performance requirements based on the maximum operating temperature. A 110–120°C-rated inner sleeve falls within the high-temperature classification of heat-shrinkable materials. The standard requires qualification testing of the complete applied system, including peel strength, cathodic disbondment, impact resistance, indentation resistance, and thermal ageing at the design temperature 58.
Primary Applications
-
Pre-insulated pipeline field joints – Carrier pipe corrosion protection at welded connections
-
High-temperature service pipelines – Design temperatures of 110°C to 120°C
-
Oil, gas, and district heating systems – Where pre-insulated construction requires reliable inner-layer protection
-
Compatible plant coatings – 3LPE, 3LPP, and FBE mainline coatings
Packaging and Availability
-
Configuration: Wraparound heat-shrinkable sleeve with closure patch
-
Dimensions: Customized to pipe diameter and joint length
-
Epoxy Primer: Supplied separately as A+B kit
-
Customization: Available for project-specific temperature ratings and dimensions
For product data sheets, ISO 21809-3 qualification reports, or project-specific technical consultation, please contact our sales team.
Keywords: high temperature inner heat shrink sleeve, pre-insulated pipe joint, 110°C heat shrink sleeve, 120°C field joint coating, carrier pipe corrosion protection, ISO 21809-3, epoxy primer, 3LPE compatible
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