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Monday, March 15, 2010: 9:30 AM
207 A/B (Henry B. Gonzales Convention Center)
Following premature failure of 3 layer polypropylene (PP) pipeline coatings, a failure investigation and analysis into this phenomenon was instigated. The failures comprised of PP cracking at field joint coating (FJC), coating disbondment and UV degradation. The PP cracking is attributed to thermal degradation and high residual stresses in PP. The coating disbondment has been found to be due to high residual stress concentration and adhesion loss after moisture interaction.
Recommendations include using a systematic approach to investigate the degree of 3LPP damage to assess the extent and severity of the 3LPP coating damage. The materials recommended for rehabilitation of 3 layer PP pipeline coatings include heat shrinkable sleeves and liquid epoxy Novolac systems. For new construction pipeline coatings – recommended candidate coatings include single layer FBE, dual layer FBE, or 3 layer PP.
New coatings shoulsd be pre-qualified with the test protocol described in this work. PP cracking in particular is a serious concern and the PP thermal stability has to be demonstrated prior to the use of the 3LPP coating system. The PP cracking is detrimental to the integrity of pipelines and it has rarely been publicized in the coating community. It is also hoped that more research can be done in the improvement of PP resin chemistry and thermal stability to achieve high integrity of the 3LPP pipeline coatings.
Recommendations include using a systematic approach to investigate the degree of 3LPP damage to assess the extent and severity of the 3LPP coating damage. The materials recommended for rehabilitation of 3 layer PP pipeline coatings include heat shrinkable sleeves and liquid epoxy Novolac systems. For new construction pipeline coatings – recommended candidate coatings include single layer FBE, dual layer FBE, or 3 layer PP.
New coatings shoulsd be pre-qualified with the test protocol described in this work. PP cracking in particular is a serious concern and the PP thermal stability has to be demonstrated prior to the use of the 3LPP coating system. The PP cracking is detrimental to the integrity of pipelines and it has rarely been publicized in the coating community. It is also hoped that more research can be done in the improvement of PP resin chemistry and thermal stability to achieve high integrity of the 3LPP pipeline coatings.