Continued from The MP Blog, p. 13. The following items relate to chemical treatment.
Please be advised that the items are
not peer-reviewed, and opinions and suggestions are entirely those of the in- quirers and respondents. NACE Interna- tional does not guarantee the accuracy of the technical solutions discussed. MP welcomes additional responses to these items. They may be edited for clarity.
Corrosion inhibitor
ing or forging? The oxide layer can't protect it in the wet environment of the atmosphere.
Q
What is the best in- hibitor to protect the outer surface of car- bon steel after hot roll-
primer is usually applied to structural steel for mild environments and short- term protection. If you are worried about IXXMIZIVKM aW] KIV IXXTa ÅVQ[P KWI\[ I\ a later date. If not, we usually left the shop primer on and forgot about it. If you want to protect it from severe corrosion for an appreciable length of time, a heavy-duty coating system appropriate for the ap- plication is called for. For steel that will be transported and installed at some LQ[\IVKM aW] UQOP\ KWV[QLMZ I ÅZ[\ KWI\ of inorganic zinc (IOZ) over a commer- cial-blasted surface. After installation, any damage can be repaired and epoxy and/ or polyurethane topcoats can be applied. The IOZ is better at resisting damage than most coatings
A
Typical inhibitors applied to the surface will not protect the steel very well, especially in wet envi- ronments. A low-cost shop
Treatment of abandoned pipe
corrosion? Is it acceptable to use seawater, biocide, oxygen scavenger, and corrosion inhibitor? What ppm do you suggest for the treatment?
Q A
Use a mixture of a corrosion in- hibitor, oxygen scavenger, and biocide (THPS). The concentra- tion should be 0.5% of the mix-
ture based on the volume of the pipeline full of water.
What is the best prac- tice to temporarily abandon a subsea pipeline to prevent
NACE International, Vol. 51, No. 11
November 2012 MATERIALS PERFORMANCE 65