Construction
Polypropylene heat shrink field joint coatings enjoys very good compatibility with the plant applied three-layer polypropylene coated linepipe.
🛠Structure:
The PP heat shrinkable sleeve is consist of irradiation cross-linked and stretched polypropylene backing and modified high shear strength polypropylene adhesive. It formed into pre-cut wrap around sleeve with a separate closure system, and applied on 2-component solvent-free liquid epoxy primer.
The Backing consists of a cross-linked and stretched polypropylene backing which is designed to partially or fully recover with heat from a touch during application. The backing also provides resistance against mechanical damage and UV resistance during construction and in service.
Frequently Asked Questions (FAQ)
Q
What is the maximum operating temperature of the 3LPP heat shrinkable sleeve?
The FRDP-PP heat shrinkable sleeve is designed for pipelines operating at buried service temperatures from ambient up to a maximum of 110°C, with a design life of 30 years. The highest design temperature for the installed sleeve system is rated at 100°C.
Q
How does the PP heat shrink sleeve compare to factory-applied 3LPP coatings?
The 3LPP HSS forms the same three-layer structure as the factory-applied 3LPP coating — comprising a liquid epoxy primer, a modified polypropylene adhesive, and a cross-linked PP backing. It is engineered to be fully compatible with plant-applied 3LPP coatings and meets or exceeds the requirements of ISO/DIS 21809-3.
Q
What role does the liquid epoxy primer play in the coating system?
The solvent-free liquid epoxy primer serves as the primary corrosion protection layer. It is specially formulated to ensure excellent compatibility and adhesion between the steel surface and the polypropylene adhesive layer, creating a robust and continuous protection system for buried field joints.
Q
What pipe diameters are available for the PP heat shrinkable sleeves?
Standard specifications cover pipe diameters from Φ168 mm up to Φ1220 mm (12 standard sizes). All sleeves have an axial length of 500 mm. Custom-made sleeves are also available to meet any specific customer requirements regarding diameter, length, or thickness.
Q
What international standards does the PP heat shrinkable sleeve comply with?
The product meets and exceeds ISO/DIS 21809-3: Petroleum and Natural Gas Industries — External Coatings for Buried or Submerged Pipelines used in Pipeline Transportation Systems — Part 3: Field Joint Coatings. Technical performance testing references ASTM D638, ASTM D2240, ASTM D570, ASTM D257, ASTM D746, ASTM D-149, ASTM D3418, ISO21809-3 Appendices A, D, and I, as well as GB/T 4507.
Q
What are the key mechanical and adhesion performance values of the installed sleeve?
The installed sleeve demonstrates strong adhesion performance: peeling strength to steel with primer is 9.8 N/mm at 23°C and 2.4 N/mm at 110°C; peeling strength to the coating layer is 6.4 N/mm at 23°C and 1.4 N/mm at 110°C. After 28-day hot water soaking, the values remain at 8.5 N/mm (to steel) and 5.5 N/mm (to coating layer), confirming long-term durability and corrosion resistance.
CYCT
