VM 80 13CR is a Martensitic OCTG steel (also called 13%Cr steel) based on API 5CT L80-13CR for sweet wet CO2 corrosive environments. VM 80 13CR offers better toughness and features finer grain size, better chemistry and more stringent inspection requirements than API 5CT PSL 2 for L80-13CR. VM 80 13CR is also available with High Collapse performance (VM 80 13CRHC).
Finer grade selection shall take into account other parameters such as Chloride content and in-situ pH.
OCTG carbon steels are known to corrode when exposed to wet CO2 containing environments. They will suffer from various forms of corrosion such as general metal loss corrosion or localized corrosion (pitting, crevice, Mesa attack).
Martensitic steel has proved to be the most cost effective solution to protect against wet CO2 corrosion in oil & gas wells.
Comparison of Cost vs time for Carbon steel + inhibitors (+ workovers) and for 13%Cr steel in wet C02 well
VM 80 13CR offers better overall performances than API L80-13CR thanks to better toughness, tighter chemical composition, finer grain size, and more stringent inspection requirements than API 5CT PSL 2 for L80-13CR:
VM 80 13CR is also available with High Collapse performance (VM 80 13CRHC)
Resistance to SSC (Sulfide Stress Cracking)
The NACE MR0175 / ISO 15156 standard limits the use of L80-13CR steel pipe to a maximum H2S partial pressure of 1.5 psi (0.1 bar) and pH ≥ 3.5.
Various industry publications and Vallourec internal test data showed that SSC resistance of 13CR steels is widely depending on other parameters such as Chloride content, water composition, test method... As showed on the ph-H2S diagram below, SSC resistance in the hatched area require close investigation such as fit-for-purpose testing.
Contact your Vallourec representative for more SSC and corrosion test data on 13CR steels.
SSC test data (NACE-A – 90%AYS – Triplicates) on L80-13CR at various content of NaCl
Over the past 30 years, Vallourec has supplied more than 150,000 tons of pipe of API L80-13CR and VM 80 13CR grades to hundreds of operators in most regions of the world for pipe from 2 3/8" to 11 ¾" OD.