Extrusion & Post
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Insufficient long-term hydrostatic strength of polyolefin plastomer PPR pipes (Variant: strengthened measures)
Problembeschreibung
PPR/PP-R pipes rupture in long-term hydrostatic tests (1000h, 8760h) and cannot meet ISO 15874 requirements.
Insufficient long-term strength affects pipe service life and design safety factor.
Especially on the original basis, additional attention is needed, and this problem is more prominent and requires key attention.
Ursachenanalyse
(1) Raw material molecular weight too low or molecular weight distribution unreasonable
(2) Extrusion temperature improper, material partially degraded
(3) Pipe wall thickness insufficient or uneven
(4) Improper cooling rate, unsuitable crystallinity
(5) Welded joint as weak point with insufficient strength
(6) On the original basis, additional attention is needed: process parameter fluctuations or equipment state changes aggravate this problem
Lösung
(1) Select special grades meeting PPR pipe standards (MFR 0.2-0.5g/10min)
(2) Strictly control extrusion temperature at 200-220°C to avoid material degradation
(3) Ensure pipe wall thickness meets SDR value requirements and is uniform
(4) Optimize cooling conditions to ensure reasonable crystallinity (50-60%)
(5) Strengthen welded joint quality control and inspection
(6) And strengthen process monitoring; on the original basis, additional attention is needed, paying special attention to parameter stability
Wichtigste Erkenntnis
Insufficient long-term hydrostatic strength is caused by material selection and processing quality, and needs to be comprehensively controlled from raw materials, process and welding.
Targeted preventive measures need to be taken in different production scenarios.
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