*4.3.1.2 Amines for film formation*

Alkylamines (R-NH2), where R is alkyl group which contains 10–20 carbon in the alkyl chain, are considered as the film-forming corrosion inhibitors. Octadecylamine (ODA) has 18 carbon atoms in the alkyl chain and is the typical amine for film formation. As ODA cannot dissolve in water, emulsifiers are usually needed for dispersion. The -NH2 in ODA can adsorb on the surface of the metal and then construct single or several layer molecular adsorption coating, which is hydrophobic and can block the aggressive medium.

The influencing factors, such as the concentration of ODA, M-alkalinity of supplemental water, temperature of condensation product, and so on, will affect the corrosion inhibition effect of ODA. For instance, under the concentration of 25 mg/L ODA in the supplemental water and in order to control the corrosion rate of iron lower than 10 mg/dm<sup>2</sup> ·day, it will extend 1 day when the M-alkalinity of CaCO3/L raise from 50 mg (2 days) to 100 mg (3 days). Therefore, the beginning corrosion inhibition effect of ODA is affected as the increase of the M-alkalinity in the supplemental water. However, it will show slight influence after the ODA film is formed. In addition, it has also reported that ODA displays the superior corrosion inhibition effect lower than 45°C. ODA performs the wonderful inhibition effect when the dissolved O2 is as low as 0.2 mg O/L; however, the inhibition effect is obviously hazarded when the concentration of dissolved O2 is as high as 3 mg O/L. Therefore, minimizing transfer of dissolved O2 from boiler to the condenser by degassing and/or O2 scavengers is extremely important to enhance the corrosion inhibition effect of ODA.

#### *4.3.1.3 Combined use of neutralizing amines and amines for film formation*

A high amount of neutralizing amine is needed to prohibit the corrosion behavior of condensing pipes effectively if the M-alkalinity of supplemental water is high; amines for film formation demand a relatively long period to fabricate the hydrophobic deposited film for preventing the corrosion of the metal. Therefore, the combining of these two kinds of amines must improve the corrosion inhibition enormously.

**Table 16** displays the corrosion inhibition synergistic effect by combining use of two kinds of the amines. With the treatment of neutralizing amine, the corrosion rate of iron drops accompanying the raise of the pH value; with the treatment

**169**

this field.

*Formulation of Corrosion Inhibitors*

**Treatment pH** 

Neutralizing amines 6.6

Combining of both 6.6

**Table 16.**

of only with single filming amine.

**5. Inhibition for oil and gas systems**

**5.1 Drilling fluid inhibitor**

**5.2 Fracturing acid inhibitor**

*DOI: http://dx.doi.org/10.5772/intechopen.88533*

**value**

7.0

7.0

*The corrosion inhibition synergistic effect by combining use of two kinds of the amines.*

of amines for film formation, the corrosion rate cut down when the pH value is reduced further. The collaborative processing outstandingly enhances the corrosion inhibition effect. Even with dissolved O2 in the condensing pipes, the combined treatment behaves the prior corrosion inhibition effect compared to the treatment

None 5.3 0 124.5

Amines for film formation 5.3 20 32.1

**Amount of the amines for film formation**

> 0 0

20 20 **Corrosion rate of iron (mg/ dm2 ·day)**

> 78.4 54.8

11.2 11.8

*4.3.2 Inhibitors used in condensate lines of boilers under moderate or high pressure*

control and stable at high temperature under moderate or high pressure.

As softened water at low temperature is usually provided for boilers under moderate or high pressure, it is not easy to cause the corrosion problems in condensate lines before entering the deaerator. However, the piping and the auxiliary apparatus after the deaerator will erode sometimes as the ill control of water quality or operation of deaerator, which is due to the rise of temperature. Therefore, the pre-control of supplemental water pipeline is as important as that of the condensate line. Neutralizing amines are then selected as the corrosion inhibitors for the supplemental water and stream condensing pipe because they are fit for pH value

As the high concentration of Cl<sup>−</sup> in the oil field sewage, and also the role of CO2,

H2S, dissolved oxygen, oil stain and miscellaneous, it results the serious pitting problems. At present, organic amine, organic polyol phosphate complex, imidazoline, and their derivatives and long carbon chain amide carboxylate are well used in

If the gas field is dominated by carbonate fracture-porosity gas reservoirs, acid fracturing is an important stimulation method to increase the production for such gas reservoirs. Therefore, the corresponding research and application of acid chemical additives, pre-fracturing fluid chemical additives, and fracturing acid

The acid solution strongly corrodes the steel, and the corrosion inhibitor is the key to ensure the smooth operation of the acidification operation. According to the long-term acidification construction experience, the degree of corrosion

inhibitors have become important tasks in the gas field development.

*Formulation of Corrosion Inhibitors DOI: http://dx.doi.org/10.5772/intechopen.88533*


**Table 16.**

*Water Chemistry*

**Table 15.**

concentrations of amines for the neutralization reaction when the concentration of CO2 is 1 mg/L. NH3·H2O is efficient for the neutralization reaction for CO2 revealed in **Table 15**; however, it is not appropriate for the copper condensate lines in boilers

**Neutralizing reagent Needed concentrations of amines for the neutralization** 

NH3·H2O 0.4 C6H13N 2.3 NH2CH2CH(CH3)OH 1.8 C4H9NO 2.0

**reaction for 1 mg/L CO2 (mg/L)**

Alkylamines (R-NH2), where R is alkyl group which contains 10–20 carbon in the alkyl chain, are considered as the film-forming corrosion inhibitors. Octadecylamine (ODA) has 18 carbon atoms in the alkyl chain and is the typical amine for film formation. As ODA cannot dissolve in water, emulsifiers are usually needed for dispersion. The -NH2 in ODA can adsorb on the surface of the metal and then construct single or several layer molecular adsorption coating, which is

The influencing factors, such as the concentration of ODA, M-alkalinity of supplemental water, temperature of condensation product, and so on, will affect the corrosion inhibition effect of ODA. For instance, under the concentration of 25 mg/L ODA in the supplemental water and in order to control the corrosion rate

CaCO3/L raise from 50 mg (2 days) to 100 mg (3 days). Therefore, the beginning corrosion inhibition effect of ODA is affected as the increase of the M-alkalinity in the supplemental water. However, it will show slight influence after the ODA film is formed. In addition, it has also reported that ODA displays the superior corrosion inhibition effect lower than 45°C. ODA performs the wonderful inhibition effect when the dissolved O2 is as low as 0.2 mg O/L; however, the inhibition effect is obviously hazarded when the concentration of dissolved O2 is as high as 3 mg O/L. Therefore, minimizing transfer of dissolved O2 from boiler to the condenser by degassing and/or O2 scavengers is extremely important to enhance the corrosion

*4.3.1.3 Combined use of neutralizing amines and amines for film formation*

A high amount of neutralizing amine is needed to prohibit the corrosion behavior of condensing pipes effectively if the M-alkalinity of supplemental water is high; amines for film formation demand a relatively long period to fabricate the hydrophobic deposited film for preventing the corrosion of the metal. Therefore, the combining of these two kinds of amines must improve the corrosion inhibition enormously. **Table 16** displays the corrosion inhibition synergistic effect by combining use of two kinds of the amines. With the treatment of neutralizing amine, the corrosion rate of iron drops accompanying the raise of the pH value; with the treatment

·day, it will extend 1 day when the M-alkalinity of

because it may accelerate copper corrosion.

*The species and amounts of amines for neutralizing CO2.*

hydrophobic and can block the aggressive medium.

*4.3.1.2 Amines for film formation*

of iron lower than 10 mg/dm<sup>2</sup>

inhibition effect of ODA.

**168**

*The corrosion inhibition synergistic effect by combining use of two kinds of the amines.*

of amines for film formation, the corrosion rate cut down when the pH value is reduced further. The collaborative processing outstandingly enhances the corrosion inhibition effect. Even with dissolved O2 in the condensing pipes, the combined treatment behaves the prior corrosion inhibition effect compared to the treatment of only with single filming amine.
