*3.1.6 Soft and lean water and environmental programs*

Acceptable cooling water programs usually use either lean water, with very low natural hardness, or ion-exchange softened water as a makeup source. In order to minimize the deposits of calcium carbonate, it must require softened water, of which the total hardness (TH) should be <5–10 ppm, to act as the makeup water


#### **Table 10.**

*Two examples of traditional molybdate formulations.*


#### **Table 11.**

*An example of the all organic program.*

according to some authorities. For comfort cooling systems, the presence of calcium carbonate deposits can in turn increase the risk of *Legionella* proliferation.

There is a tendency to operate cooling systems at high cycles of concentration with lean waters, perhaps 10–15 times COC, depending on the particular circumstances (including the limitation of COC for the cooling system). It is not only considering the economic benefits but also reducing the inherent highly corrosive nature in most low-calcium waters. A further benefit is that it may permit the presence of sufficient calcium to serve as a corrosion inhibitor in combination with a silicate, phosphate, or phosphonate formulation component with high COC.

Various programs exist to provide satisfactory corrosion inhibition and good deposit control. The formulations include the inhibitors noted previously. It is important that the selected type of formulation must match the operating conditions because sludge may form in the cooling system with numerous cycles. Also, if bromine is used, certain organic inhibitors may be oxidized, thus compromising the program's effectiveness with the long retention times. The formulations may also be modified to remove all metals and phosphorus-containing compounds. A typical formulation is shown in **Table 12**. This is designed to be used at 125–175 ppm reserve in a cooling water system operating at high COC.

#### *3.1.7 Closed-loop programs*

There is a wide range of metals used in the construction of closed-loop circuits, and the usual differences are the properties of the circulating water (ranging from deionized water to glycol mixtures to brine water). As a consequence, it is not possible to devise a single water treatment formulation that satisfies the requirements of all closed-loop circuits. In addition, some formulators add oxygen scavengers or indicator dyes in their blends additionally. An example of a formulation suitable for a closed-loop circuit, which is primarily for carbon steel construction, is as shown in **Table 13**. The minimal whole product reserve to be maintained in the closed-loop circuit ranges from 350 to 700 ppm (calculated as nitrite).

#### **3.2 Hot-water inhibitor**

The function of the oil well heat-tracing system is to prevent the oil temperature at the oil well exit from decreasing rapidly and to ensure that the oil production


**165**

*Formulation of Corrosion Inhibitors*

**Table 13.**

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

increases the cost of water treatment.

*A typical formulation for closed-loop program.*

**4. Inhibitors for alkaline solution**

adding alkali and using corrosion inhibitor.

*4.1.1 Extrude dissolved O2 and CO2*

**4.1 Boiler water inhibitors**

fluid flows normally to the gas collection station. Hot-water continuous circulation, many sources of water supply, and high operating temperature will cause severe corrosion and scaling in the heat-tracing system. In the most corrosive areas, some pipelines are even perforated once a week, which brings great hidden dangers to the

**Basic materials Closed-loop formulation (%)**

NaOH, commercial solution 15 Borax 6 Sodium silicate 8 Sodium nitrite 30 PAA 3 TTA, commercial solution 2 Water 36 Total 100

Hot-water boilers and heating systems generally use alkaline chemicals for water treatment to prevent corrosion and fouling of boilers and heating systems. However, due to the increasing use of heating equipment made of copper and aluminum in heating systems, corrosion is very serious under alkaline water

conditions. In particular, radiators made of aluminum are often perforated by alkali corrosion in less than one heating period. Therefore, if there is heating equipment made of copper or aluminum in the hot-water boiler and heating system, it is necessary to add additional copper and aluminum corrosion inhibitor, which greatly

Supplemental water for boilers should be chemically treated in advance, for lowering the possibility of corrosion and scaling to increase the heat transfer effect. Steam is often needed for power generation, thus deposition of SiO2 on the turbine blades is inevitable if enough silicon component is contained in supplemental water. It is necessary to control the scaling by getting rid of the Ca2+ and Mg2+ with different kinds of methods, such as by ion-exchange resin and apposite precipitants. In order to control the corrosion process, the essential treatments include degassing,

If residual dissolved O2 in the supplemental water obeys stoichiometric ratio with the metal ions in the boiler system under the conditions of high pressure, it will cause serious pitting of the metal tubes. Degassing of the supplemental water and then adding of appropriate scavenger, such as Na2SO3 and N2H4, is the effective method for deoxygenation. The acceptable concentration of O2 should be kept lower than 0.005 ppm. Degassing may cause the reduction of CO2 content, especially if the supplemental water is pre-acidified to release H2CO3 from the dissolved

normal production of oil wells and also causes a large energy waste.

#### **Table 12.**

*A typical formulation for soft and lean water.*


**Table 13.**

*Water Chemistry*

according to some authorities. For comfort cooling systems, the presence of calcium

There is a tendency to operate cooling systems at high cycles of concentration with lean waters, perhaps 10–15 times COC, depending on the particular circumstances (including the limitation of COC for the cooling system). It is not only considering the economic benefits but also reducing the inherent highly corrosive nature in most low-calcium waters. A further benefit is that it may permit the presence of sufficient calcium to serve as a corrosion inhibitor in combination with a silicate, phosphate, or phosphonate formulation component with high COC. Various programs exist to provide satisfactory corrosion inhibition and good deposit control. The formulations include the inhibitors noted previously. It is important that the selected type of formulation must match the operating conditions because sludge may form in the cooling system with numerous cycles. Also, if bromine is used, certain organic inhibitors may be oxidized, thus compromising the program's effectiveness with the long retention times. The formulations may also be modified to remove all metals and phosphorus-containing compounds. A typical formulation is shown in **Table 12**. This is designed to be used at 125–175 ppm

There is a wide range of metals used in the construction of closed-loop circuits, and the usual differences are the properties of the circulating water (ranging from deionized water to glycol mixtures to brine water). As a consequence, it is not possible to devise a single water treatment formulation that satisfies the requirements of all closed-loop circuits. In addition, some formulators add oxygen scavengers or indicator dyes in their blends additionally. An example of a formulation suitable for a closed-loop circuit, which is primarily for carbon steel construction, is as shown in **Table 13**. The minimal whole product reserve to be maintained in the closed-loop

The function of the oil well heat-tracing system is to prevent the oil temperature

at the oil well exit from decreasing rapidly and to ensure that the oil production

**Basic materials Formulation (%)** NaOH, commercial solution 10 TKPP, commercial solution 5 Sodium silicate 25 EDTA, commercial solution 6 MA/EA/VA 4 PAA 5 TTA, commercial solution 3 PEG 2 Water 40 Total 100

carbonate deposits can in turn increase the risk of *Legionella* proliferation.

reserve in a cooling water system operating at high COC.

circuit ranges from 350 to 700 ppm (calculated as nitrite).

*3.1.7 Closed-loop programs*

**3.2 Hot-water inhibitor**

**164**

**Table 12.**

*A typical formulation for soft and lean water.*

*A typical formulation for closed-loop program.*

fluid flows normally to the gas collection station. Hot-water continuous circulation, many sources of water supply, and high operating temperature will cause severe corrosion and scaling in the heat-tracing system. In the most corrosive areas, some pipelines are even perforated once a week, which brings great hidden dangers to the normal production of oil wells and also causes a large energy waste.

Hot-water boilers and heating systems generally use alkaline chemicals for water treatment to prevent corrosion and fouling of boilers and heating systems. However, due to the increasing use of heating equipment made of copper and aluminum in heating systems, corrosion is very serious under alkaline water conditions. In particular, radiators made of aluminum are often perforated by alkali corrosion in less than one heating period. Therefore, if there is heating equipment made of copper or aluminum in the hot-water boiler and heating system, it is necessary to add additional copper and aluminum corrosion inhibitor, which greatly increases the cost of water treatment.
