Abstract
Mechanically Lined Pipes (MLP) have shown to be a cost effective solution in several oil fields for risers and flowlines, based on the fact that only a small thickness of the pipe is produced with corrosion resistant alloys (CRA). Only the CRA liner will be exposed to the corrosive conditions inside the pipe, which can vary between different projects.
From the beginning, mainly nickel alloys such as N08825 and N06625 have been selected for MLPs. Lately, stainless steels have been increasing its presence in this application. Grades like UNS S31603, UNS S31703, UNS N08904 are already utilized in MLPs. Alternatively, higher corrosion resistant grades like UNS S31254, UNS N08935 and UNS S32654 could be a good fit. The introduction of additional alloys to this application enables better optimization of material selection in terms of performance and cost.
This paper aims at reviewing and comparing the aspects of the different CRAs available for MLPs. Among the aspects evaluated are mechanical properties, localized corrosion resistance, chloride stress corrosion cracking, resistance to sour service environments as well as commercial aspect pertinent to this application.
