External Anti-Corrosive Technology for Submarine Pipeline Nodes and Its Effect on Cathodic Protection

Abstract

The anti-corrosive failure of on-site welding points (nodes) of submarine pipelines is the main factor affecting the external anticorrosive failure of pipelines.The quality of anti-corrosive coatings directly affects the safe operation of the entire submarine pipeline.The anticorrosion of nodes in submarine pipelines generally adopts the forms of heat shrink band， fusion bonded epoxy powder， and composite coating.Compared to heat shrink band and fusion bonded epoxy powder， the coating damage rate of composite coating node anti-corrosive materials was the lowest.The anti-corrosive pipe filled with nodes had a lower coating damage rate than the unfilled anti-corrosive pipe.The filling at nodes not only provided mechanical protection， but also affected the current demand value for cathodic protection.In addition， research showed that the coating damage rate of 3LPP coating anti-corrosive pipeline was lower than that of FBE and 3LPE coating anti-corrosive pipeline， and the coating damage rate of insulated pipeline was the lowest.Submarine insulated pipelines had a shielding effect on cathodic protection current.Only when there was a damage to the node anti-corrosive layer， the cathodic protection current flowed into the surface of the protected pipeline to protect the pipeline.

Keywords

• submarine pipeline|single layer insulation pipe|external anti-corrosion of nodes|coating damage rate|waterproof caps|cathodic protection