A substance dosed at parts per million into water, oil, gas or acid that cuts corrosion by forming a film, passivating the surface or changing the environment. Filming amines and imidazolines coat steel in oil and gas lines; phosphates, molybdates and azoles serve cooling water; volatile inhibitors protect closed spaces. Inhibitors go in by continuous injection or batch treatment, and the dose is tuned with coupons, probes and residual tests.
Batch the line with corrosion inhibitor behind a pig every two weeks and keep continuous injection at 20 ppm.
An inhibitor only protects metal it reaches. Low spots, dead legs and the steel under deposits see little of it, which is why pigging and inhibition go together.
Also heard as
- inhibitor
- CI
- filmer
- filming amine
Related terms
Oxygen scavenger
Chemical that strips dissolved oxygen from water to stop oxygen pitting in boilers and injection systems.
ER probe
Electrical resistance probe that tracks corrosion by measuring the rising resistance of a thinning metal element.
LPR
Linear polarization resistance: an electrochemical method that reads corrosion rate in minutes in conductive liquids.
Corrosion coupon
Weighed metal strip exposed inside a system for a set time, then reweighed to calculate corrosion rate.