ANGUS Chemical CompanyTechnical Bulletin

AMP-95®

CORROSION INHIBITOR IN STEAM-CONDENSATE LINES

TB 41

AMP-95 (2-amino-2-methyl-1-propanol containing5% water) is an effective and efficientneutralizing amine for use in preventingcorrosion in steam-boiler condensate-returnlines and steam turbines. When used in thisapplication, AMP-95 provides the followingbenefits:

� Superior base strength for effective pH controland excellent corrosion protection.

� Favorable distribution ratio for improvedcorrosion inhibition in the condensate line.

� Thermal stability essential for use in mediumpressure systems.

� Superior CO2 removal from feedwater andcondensate through efficient amineregeneration in the deaerator.

� High boiling point with no amine/waterazeotrope to increase amine loss in deaeratorsystems.

� Complete solubility and compatibility withother commonly-used boiler water treatmentchemicals.

� Safety advantages in terms of toxicity andflammability in comparison to othercommonly-used amines.

� Maximum efficiency at pressures between 100psi and 1000 psi.

Typical Properties

The following are typical properties of AMP-95; they arenot to be considered product specifications.

Neutral Equivalent. . . . . . . . . . . . . . . . . . . . . . . . . . . 93-97Specific Gravity @ 25/25ºC. . . . . . . . . . . . . . . . . . . . 0.942Weight per Gallon @ 25ºC . . . . . . . . . . . . . . . . . . . 7.85 lbViscosity @ 25ºC (77ºF) . . . . . . . . . . . . . . . . . . . . . 147 cp

@ 10ºC (50ºF) . . . . . . . . . . . . . . . . . . . . . 561 cpCoefficient of Expansion, 20 to 90ºC . . . . . . . . 0.00096/ºCFlash Point, Tag Closed Cup . . . . . . . . . . . . . . 83ºC/182ºF

Pensky-Martens Closed Cup. . . . 87ºC/188ºFVapor Pressure @ 20ºC mm Hg/Pascal . . . . . . . 0.08/10.4Freezing Point . . . . . . . . . . . . . . . . . . . . . . . . . –2ºC (28ºF)Surface Tension, neat . . . . . . . . . . . . . . . . 36-38 dynes/cm

in 10% Aqueous Solution. . . . . . . . . . . . . ~58 dynes/cmpH of 0.1M Aqueous Solution @ 20ºC (68ºF) . . . . . . . 11.3pKa @ 25ºC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.72Refractive Index, nd, @ 20ºC. . . . . . . . . . . . . . . . . . 1.4568

A subsidiary of The Dow Chemical Company

ANGUS Chemical Company1500 E. Lake Cook RoadBuffalo Grove, IL 60089

Phone: 847-215-8600Toll Free: 800-447-4369Fax: 847-215-8626

How Amines Provide Corrosion Protection

Most boiler systems are constructed of steel- and copper-bearing metals, which are subject to acid corrosion orerosion. Boiler feedwater contains naturally occurringcarbonates and biocarbonates which thermallydecompose in the boiler, releasing carbon dioxide (CO2)into the systems. When steam condenses to water, thisCO2 dissolves in the water to form corrosive carbonic acid.The corrosion which results can lead to damage andunscheduled shutdown of steam generating systems.Volatile amines, such as AMP-95, control this corrosion byneutralizing acidity.

AMP—The Preferred Amine

The following graph illustrates the neutralization of watercontaining 32 mg/L (ppm) of CO2 with four aminescommonly used for boiler water treatment. AMP is themost efficient of these amines in bringing the pH into thedesired range for corrosion control.

The superiority of AMP to other amines has been shownfor boiler feed-water across the range of CO2 levelscommonly encountered, as shown in the following table:

Corrosion Inhibition

AMP-95 has demonstrated unmatched performance inlaboratory tests and field surveys of corrosion inhibitionin operating steam generation systems. In a 550 psig(3.79 kPa) steam generating plant producing approximately10 million pounds of steam per day (1260 kg/sec), AMP-95 significantly retarded the corrosion rates of ironand copper in piping and turbine areas in comparison tothe morpholine treatment used over the previous 12-month period.

Copper Loss by Corrosion

Average Over With 30 mg/LLocation Previous 12 Months (ppm) AMP-95

Feedwater 0.225 mg/L 0.01 mg/L550 psigSteam header 0.460 0.01-0.04150 psigSteam header 0.465 0.0350 psigSteam header 0.475 0.02-0.03

Iron Loss by Corrosion

Average Over With 30 mg/LLocation Previous 12 Months (ppm) AMP-95

Feedwater 0.065 mg/L 0.033550 psigSteam header 0.176 0.010150 psigSteam header 0.077 0.03350 psigSteam header 0.079 0.065

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Level of Amine (ppm) Required To Reach OperatingNoncorrosive Conditions in Condensate Water

CO2 Level in Steam 18 mg/L (ppm) 32 mg/L (ppm) 58 mg/L (ppm)Desired pH 7.5 8.0 7.5 8.0 7.5 8.0AMP 27 29 62 67 119 127

Morpholine 37 50 77 125 140 >140Cyclohexylamine 38 41 67 69 124 131Diethylaminoethanol (DEAE) 35 39 72 76 130 135

The ultimate criterion for neutralizing amines in corrosioninhibition is the pH of the steam condensate at differentsampling points throughout the steam-distributionand condensate-return systems. A concentration inthe feedwater of approximately 30 mg/L (ppm) AMPproduced the following pH values at system equilibriumin the field survey.

Location pH

Feedwater 9.53550 psig Steam header 7.70150 psig Steam header 8.11

50 psig Steam header 7.56550 psig Steam line 1500 feet away 7.57550 psig Steam line 2 miles away 6.98

Corrosion potential increases as the pH value drops. ThepH is easily regulated at the desired level by varying theamount of AMP-95 used. With steam generated at 550psig and at a concentration of 25-30 ppm AMP in thefeedwater, approximately 1 mg/L (ppm) of AMP wascarried to outlying areas (1-2 miles).

In a 1500 psig (10.342 kPa) high pressure boiler, AMP-95and morpholine were compared for pH control andcondensate system protection. Both amines were fed intothe boiler at equivalent rates. The following data reportthe comparative pH values averaged for nine differentsampling points and average corrosion values determinedfrom iron coupons exposed to the condensate as theboiler was operating (ASTM D2688-70).

Iron Coupon Corrosion

Average Penetrationmils/yr mm/yr

AMP-95 5.8 0.147Morpholine 6.3 0.160

Distribution Ratio

An important measure of the suitability of a neutralizingamine is its distribution ratio, i.e., the concentration ofamine in the vapor phase divided by the concentration ofamine in the liquid phase. Without sufficient volatility, noamine will be present in the steam to neutralize thedissolved carbon dioxide in the condensate. The amineinstead will concentrate in the boiler water, causingexcessive losses through blowdown. Conversely, anamine with high volatility readily leaves the boiler waterand affords little, if any, corrosion protection in the firstcondensate region of the system.

The amount of AMP-95 which volatilizes with the steamis a function of both AMP concentration and pressure inthe boiler. As pressure and/or amine concentration isincreased, AMP will more preferentially partition itself intothe steam phase. The table below (entitled “Variation ofDistribution Ratio”) presents experimentally determineddistribution ratios for various amines at 100-1500 psig(0.689-10.342 kPa) steam and 164-314ºC (327-597ºF) ina stainless steel research boiler utilizing characteristicboiler water of 15 cycles concentration.

The intermediate distribution ratio of AMP-95(approximately 50/50 distribution between steam andcondensate) lends itself well to superior protection ofcondensate lines throughout the system. Industrial steampiping with very long runs may require a blend of AMP-95with another more volatile amine to insure adequateprotection.

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pH Control

Deaerator 50 psig 550 psigIn Feedwater Blowdown Condensate Condensate

AMP-95 8.31 8.46 10.08 8.60 8.59Morpholine 7.88 7.98 9.61 8.26 8.24

Variation of Distribution Ratio with Pressure for Various Amines

Pressure, psig 0 100 200 300 400 500 600 700 900 1100 1300 1450

AMP-95 0.1 0.47 0.95 0.84 0.85 0.85 0.85 0.82 0.91 0.90 0.93 0.92Morpholine 0.4 0.98 1.6 1.4 1.2 1.2 1.3 1.2 1.3 1.3 1.3 1.2DEAE 1.0 3.4 4.5 4.4 3.9 3.8 3.9 3.5 3.3 2.6 2.9 2.7Cyclohexylamine 2.0 9.3 23.3 19.5 8.0 6.7 6.6 6.1 5.3 4.7 4.4 4.1

CO2 Absorption and Carbonate Dissociation

Effective treatment of condensate water requiresneutralization of carbonic acid in the water phase andlater dissociation to release CO2. AMP-95 demonstratesexcellent affinity for CO2, but it is easily regeneratedwithout excessive losses through volatility or azeotropewith water.

In comparison with other commonly-utilized amines,AMP-95 has a high base strength. This advantage isshown by differences in CO2 absorption in 25% solutionsof the volatile amines at 28ºC.

Amine Weight % CO2, Absorbed

AMP 10.43Cyclohexylamine 8.27Morpholine 7.75

In addition to its superior ability to absorb CO2 andneutralize carbonic acid, AMP-95 also demonstrates theability to release CO2 in the deaerator with minimal volatileamine loss. The amine carbonate dissociates in thedeaerator allowing AMP to return to the boiler with thecondensate.

Solutions prepared with 100 mg/L (ppm) amine and 50mg/L (ppm) CO2 at an approximate pH of 7.0 were heatedto 100ºC and monitored for their level of CO2 forcomparison. The data shown in the following figuredemonstrate the excellent desorption ability of AMP-95.

Deaerator Losses

One of the major areas of amine loss in a system can bein the deaerating-heater section. Deaerator temperaturesabove 220ºF are commonplace. Neutralizing amines mayaccompany the gases vented from the deaerator,particularly those amines which form azeotropes withwater. AMP boils at 329ºF and does not form anazeotrope with water. The following table ranks potentialfor amine loss from the amine most easily lost to thatbest retained.

Ratio in Boiling PointAmine System Azeotrope at 1 atm

Cyclohexylamine/Water 44/56 205ºF

Diethylamine-ethanol/Water 26/74 210

Morpholine/Water nonazeotrope 262AMP/Water nonazeotrope 329

In a laboratory test designed to simulate deaeratorconditions, it was found that AMP was lost at the rate of0.5% by wt. per minute. Under the same conditions, theloss for other commonly-used amines was: morpholine,1.0% per minute; cyclohexylamine, 1.7% per minuteand diethylaminoethanol, 3.0% per minute. The ability ofAMP-95 to rapidly dissociate from CO2 in the deaeratorwithout significant amine loss, coupled with its superiorability to absorb carbon dioxide in the feedwater/condensate, make it the amine of choice for corrosioncontrol of condensate lines and steam turbines.

Thermal Stability

The stability of volatile amines is of considerable concernbecause the most common breakdown product, ammonia,can be highly corrosive to condensate systems and steamturbines. Field experience in several boiler systems atpressures up to 1500 psig (10.342 kPa) has revealed nodetrimental effects from the use of AMP-95.

Laboratory experiments were conducted to determine ifammonia was produced from AMP under conditions ofuse. High levels of amine were used to exaggeratepossible decomposition. Deionized water containing 500mg/L (ppm) of AMP was held at 600 psig (225ºC) for 24hours. Additionally, deionized water containing 1000 mg/L(ppm) of AMP was held at 600 psig (4.137 kPa) for 48hours. No ammonia was present in samples analyzed atthe conclusion of these test runs.

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AMP-95 is classified as a combustible material. However,because of its high flash point, AMP-95 has a highermargin of safety than do other amines commonly used, asis shown by the flash point data in the following table:

Flash PointAmine (TCC)

AMP-95 182ºFCyclohexylamine 83Morpholine 95Diethylaminoethanol 120

Shipping and Packaging

AMP-95 is classified, according to Title 49 (the U.S.Department of Transportation or DOT regulations) as acombustible liquid, but it is only subject to theseregulations when shipped in bulk in tank cars, tank trucksand intermediate bulk containers (tote tanks). It is notsubject to any of the requirements of DOT regulationswhen shipped in “non-bulk” packaging (capacity less than450 liters or 119 gallons). The bill of lading descriptionsused by ANGUS for bulk and packaged shipments of thisproduct are:

Bulk Shipments:COMBUSTIBLE LIQUID NOS (2-AMINO-2-METHYL-1-PROPANOL), NA1993,III. IN CASE OF EMERGENCYUSE DOT GUIDE 128 ATTACHED.TRADE NAME = AMP-95

Shipments in non-bulk packaging:CHEMICALS NOI (2-AMINO-2-METHYL-1-PROPANOL)NO HAZARD CLASS LABELS OR PLACARDSREQUIRED.TRADE NAME = AMP-95

AMP-95 does not meet any of the defined criteria for“dangerous goods” contained in the internationaltransportation regulations for air (ICAO TechnicalInstructions) or for ocean transport (IMDG Code).

Shipping Containers Net Wt. Gross Wt.

5-gallon unlined steel drums 35 lb 40 lb55-gallon unlined steel drums 420 lb 460 lb

The shipping containers listed above meet UN 1A1packaging specifications. AMP-95 is also available forshipment within the U.S. in 350-gallon stainless steelintermediate bulk containers. They have a net weight of2740 lb and a gross shipping weight of 3215 lb.

Further confirmation of the stability of AMP wasdemonstrated in an evaluation of amines for thermalstability by modified differential thermal analysis. AMPproved to be quite stable in this test. Listed in the tablebelow are the temperatures at which decomposition wasfirst noted in the undiluted amines.

DecompositionAmine Temperature

DEAE >400ºC >750ºFAMP 360 680Morpholine 340 644Cyclohexylamine 330 626

Toxicity

AMP-95 causes eye burns. Wear protective goggles forany operation in which splashing is likely to occur. In caseof eye contact, immediately flush eyes with plenty of waterfor at least 15 minutes; see a physician.

Prolonged or frequently repeated exposure of the skin toAMP-95 may result in skin irritation. When such exposureis unavoidable, use of protective clothing is advised. Incase of skin contact, wash the exposed area thoroughlywith water. Remove contaminated clothing and washbefore reuse. Discard contaminated shoes.

The vapor pressure of AMP-95 is quite low. Hence therewill be only a small concentration of vapors at ordinarytemperatures of use. Avoid repeated inhalation exposureto vapors or mists from heated material as the effects ofinhalation have not been fully evaluated.

The acute oral LD50 for AMP is 2.9 g/kg when tested inrats. Intraperitoneal administration to mice gave an LD50 of0.32 g/kg. Thus, AMP-95 would be considered as onlyslightly toxic by either route of administration.

AMP-95 when neutralized with fatty acids, as in the use foremulsification, has much less potential for irritation of skinor eyes. In several decades of use, there have been noreports of dermatitis resulting from exposure to its fatty acidsoaps. Oral ingestion by rats of solutions containing 3 g/kgof the stearate soap of AMP produced no acute toxic symp-toms or death.

Safety in Handling

AMP-95 is a colorless, mobile liquid with low odor. It hasa relatively low viscosity of 560 cp at 50ºF. AMP-95 iseasily poured or pumped into mixing systems, whereit is miscible in all ratios with water. AMP-95 is alsocompatible with other components, both organic andinorganic, commonly used with neutralizing amines inwater treatment.

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AMP-95 is a Registered Trademarkof ANGUS Chemical Company.

GJT/JCR – Form No. 319-00036© 2000 by ANGUS Chemical Company.All Rights Reserved. Printed in U.S.A.

The information and data contained herein are believed to be correct. However, we do not warranteither expressly or by implication the accuracy thereof. In presenting uses for this product, noattempt has been made to investigate or discuss any patent situations which may be involved.

A subsidiary of The Dow Chemical Company