3 Layer Heat Shrink Technology with “Gel-State” Epoxy Installation
Marcia Navarro
Marcia Navarro
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Two type of  3L heat shrinkable sleeves (3LHSS) application methods, the induction heated force cured epoxy (FCE) and the ‘’gel state’’ (GS) methodology were investigated. The FCE uses higher application temperatures, above 120°C, whereas the GS is normally below 90°C.  Because of this, GS application preserves the integrity of the FBE of the 3LPE coated pipes.

In this study, 3LHSS have been installed using FCE and GS. The FCE installations without sleeves on top were used as reference to measure epoxy thickness, hardness shore D and cross cut adhesion. For the GS application, two conditioning steps were considered, room temperature and quenching in a water bath, followed by evaluation of same properties as the FCE sample. Results were found in line to those of the reference installation.

Furthermore, we evaluated the adhesion resistance to temperature of two different grades of  FBE by preconditioning 3LPE pipes at 130°C and 140°C for 2, 5 and 10 min, in order to simulate the 3LHSS field conditions and followed by Hot Water Immersion (HWI) Test  at 85°C during 9, 28 and 50 days (ISO 21809-3). After HWI test, peel adhesion of the FBE was made at 23°C (ISO 21809-3). Results demonstrated that FBE can be affected by high temperatures and in presence of water.

Finally, three different 3LHSS Coatings where applied using two type of installations FCE and GS. The coatings were exposed to cathodic disbonment test at 85°C for 28 days (ISO 21809-3). The results revealed that some coatings were more effective in cathodic disbondment when applied by the GS method instead of the FCE.   It was concluded that specific interactions contribute to bond durability after the cathodic disbonment tests even if applied by GS. This would in turn prevent the FBE from weakening and detaching from the steel pipes.

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