CORROSION/MAINTENANCE

Iron Sulfides—effect on amine plantsAmine plants treating gas containing H2S will have iron sulfides in thesystem. Here's where they help and hinder plant operation

B. SPOONER and M. SHEILAN, Amine Experts Inc., Calgary, Alberta, Canada

I n sour-gas production the two primary corrosion-causing spe-cies are hydrogen sulfide {H2S) and carbon dioxide (CO,).The corrosion products that torm from the reaction of these

gases with steel in rhe presence of water can provide a clue as tothe formation mechanism, severity ofthe potential corrosiveenvironment and degree co which the corrosion will affect amineunit operation.

In any amine system, piping and equipment corrosion is oneofthe worst ofthe potential prohlenis an operator or engineer canencounter. Amine plants treating gas containing H^S «'///haveiron sulfides in the s}'stem. Are they a good thing? When do theyhelp and when do they hinder? This article will attempt to clarifythe pros and cons ofthe presence of iron sulfides.

The basics. Corrosion may he defined as the chemical or elec-trochemical reaction hetween a material, usually a metal, and itsenvironment. The reaction causes deterioration ofthe material.

Corrosion is a natural process that is continuously takingplace everywhere within an amine plant (piping systems, processvessels, etc.) to some degree. Steel, which h an iron alloy, is themost prone to destruction hy corrosion in gas processing. Whenexposed to difFerenc oxidizing environments, a metallic iron triesto reach its natural state of iron oxide. Corrosion is a process thatcan be reduced but not eliminated.

Pure iron is not found in nature: rather, it is in the form of rediron oxide. To convert it to a usable metal, the oxygen is removed,leaving hehind pure iron. Pure Iron will eventually revert hack toits natural oxide state, which is commonly called rust. Iron mayhe comhined with other metals to form alloys that improve itsproperties and retard (but not eliminate) iron oxide tormation.Oxygen is the main catalyst tor the corrosion process, and ofcourse oxygen is everywhere in the environment.

Iron ionization. Iron can also corrode in the presence of anelectrolytic fluid, such as an aqueous amine solution, as a resultof ionization. The fundamental step in steel corrosion is the pro-cess by which the valence electrons are removed from iron in itsmetallic state. When these electrons are removed, the iron atomis left with 3 positive charge and is no longer able to participate inthe metallic bonding. The positively charged species must leavethe metallic environment and go somewhere else. The process isrepresented as:

Fe, Fe 4-2e (1)

stopping the reaction... unless the negative charge in the metal issomehow reduced:

• H' ions can do this by reacting with the electrons (e-) toform atomic hydrogen

• If the "circuit" is completed in this way, corrosion will con-tinue until the system runs out of either Fe or H*

Since pH is an inverse log relationship, for every decrease of 1"pH point" the quantity of H' ions is increased by a factor of 10.This explains the increased corrosive tendency of low-pH fluids(acids). They have orders of magnitude more H* ions than basicsolutions (amines) and, therefore, have almost an unlimited sup-ply of H* ions to feed the corrosion cell (in eftect, low pH leadsto an increased corrosion current feeding the corrosion "lightbulb").

Fe (lh)

FJectrons cannot survive in an aqueous solution; diey "hide"in the metal, making it negatively charged (polarized), eventually

H2S corrosion. HiS dissolves in water; however, the bond isvery weak. HiS will liberate itself from the water with the slight-est agitation, reduction in pH or contact with reactive material.The intent of this article is to provide a basic understanding ofthe corrosion mechanisms associated with HiS attack on amineplants, how to recognize the conditions that affect corrosion sever-ity and to gain an understanding ofthe recommended operatingparameters to get the most out of ihe facility in terms of handlingthe ingress and formation of iron sulfide (FeS).

Note that there are a number of complex reaction mechanismsassociated with corrosion (especially in the presence of water).The study of these corrosion mechanisms is tar from trivial, butbeyond the scope of this article. Presented here are simplisticrepresentations ofthe primar)' reaction steps.

Iron sulfides. FeS is the reaction product of iron (Fe) andsulfur (S) in the absence of oxygen. More specifically to aminesystems, this reaction is between iron and HiS. This initial reac-tion is a form of metal corrosion; however, under ideal conditionsthe FeS formed then "sticks" to the walls oí the piping and vesselinternals and acts as a protective film thus retarding further metalcorrosion. This mechanism is actually one of the main reasonswhy carbon steel is used in amine plant construction.

The reaction mechanism of HiS with steel that results in form-ing FeS is complex and occurs hy several intermediate reactions.The simplified reaction can he written as:

(2)

50 MARCH 20Î0 HYDROCARBON PROCESSING

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This reaction only takes place in the presence of water.Rtist left in the system or pipeline can also lead to FeS forma-

tion:

Fe,O, (rust)-|~ 3H2S—*• 2FeS-f-3H2O-l-S (3)

Several species or types of FeS; the most commonly found inamine systems, in order of increasing sulfidacion, are:

Mackinawite—FeSj., or Fe],,S—is the most soluble type ofFeS, as well as most reactive with oxygen.

Pyrrhotite—Fej.^S—iron-deficient sulfide. More stable thanmackinawite.

Pyrite—FeSi—most stable form of FeS.Other types of FeS that may be found;Greigite—Fe3S4 - product of sulphidisation of mackinawiceTroilite—FeS - stoichiometric iron sulfide - rarely found in

amine systems (found in meteorites).HiS will attack steel very fast. The reaction is partly the solid-

state diffusion of iron in Fei. S, and partly the fracturing of thesulfide layer to admit more H2S to the iron surface. There are noknown field methods to differentiate one FeS spedes from another,the most common laboratory method is by x-ray difïraccion.

Mackinawite is the inicial FeS form that normally develops inamine systems. It is fairly soluble, and does not form as strongof a protective layer on the piping wall compared to pyrrhotiteor pyrite. Mackinawite is normally the main component in the"black shoe polish" often seen on rich-side particle filters. Theodier components are hydrocarhon and polymerized amine. TTierecan still be some FeS scale on piping and vessel walls when the FeSis mackinawite beaiuse the formation rate is much faster than thedissolution rate back iitto the amine.

As more and more H2S reacts with the mackinawite the ratioof sulfur CO iron grows and will eventually change che molecularstructure of the FeS molecule. With adequate HjS partial pre.ssure,mackinawite will convert co pyrrhotite quickly ac temperaturesabove 43''C(10rF).

Pyrrhotite is less soluble than mackinawite and makes a verygood protective film. Pyrrhotite will deposit on piping wallsbetween 43 and 15O'*C (109-302''F).

Pyrite is formed when the ratio of suIftir to iron reaches 2:1.Elemental sulfur can also react with iron to make pyrite, makingit common in regenerator bottoms and reboilers. It has extremelylow solubility levels and is che hardest FeS type. Pyrite, choughvery durable, is not a preferred procective film. If even the small-est space exists between it and carbon steel, a galvanic cell can beformed between the pipe wall and pyrite that will result in veryhigh corrosion rates.

The properties of an FeS film depend on the surroundingenvironment. Temperature, pH, fluid dynamics, HjS and CO3partial pressures and che presence of inhibitors or surfactantsall have an effect on the film properties. Normally, a good scaleis only a few molecules thick, however, it can grow thicker andcontain wax, asphalcenes, calcite, etc. These "extras", dependingon how much of each is present, can cause tbe scale to be soft andmushy or hard and brittle.

Iron sulfide advantages. If the FeS scale is strong enough,it will adhere to che piping surface, forming a protective or pas-sivating film. Unless removed (which can happen by a number ofmechanisms discussed later), this film pre\'ents further pipe andvessel corrosion and can result in extremely long life spans for thatpart ofthe amine plant.

TABLf 1. typical types of FeS scale formation

Plant area

Absorber—uppei section

Absorber—lower section

Rich piping bEpfore lean/rich exchanger

Rich piping after lean/rich exdiangw

Regenerator—upper section

Regenerator—lower section

Reboiler

Lean piping before lesn/rich exchanger

Lean piping after lean/rich exchanger(including cooler)

High HjSpartial pressure

Mackinawite

Pyrrhotite

Pyrrhotite

Pyrrhotite/pyrite

Pyrrhotite/pyrite

Pyrite

Pyrite

Pyrite

Mackinawite

t.ow HjSpartial pressure

Mackinawite

Mackinawite

Mackinawite

Pyrrhotite

Pyrrhotrte

Pyrite

Pyrite

Pyrite

Mackinawite

The main advantage of FeS in an amine system then, is thatonce formed and adhering to the piping and vessel walls, theFeS protects the plant from further corrosion. It is importantto note, however, that FeS may have formed a strong protectivelayer in one pan of a plant but not in others (Table I).

Iron sulfide disadvantages. Fiaving H^S in the inlet gasdoes not necessarily mean [he resulting FeS formed in the systemwill form a protective layer on the piping wails. As previously dis-cussed, H2S partial pressure appears to make a large contributionto che scale depth and quality. Once the scale is compromised, thechance of developing a galvanic-tj'pe corrosion cell is increased.Weaker scales are also easily removed or subject to delamination,allowing for the potential ingress of COji under the deposit andthe subsequent agressive under-deposit corrosion that can leadto significant metal failures.

FeS particles can also enter a facility via the feed gas stream.Ideally they are removed by the inlet separation devices; however,this is not always the case. If allowed to enter an amine unit, theFeS will most likely be removed by the amine solution (whichacts like a water-wash column; another good way to remove FeSupstream of a process). In these cases, the FeS will simply add tothe system suspended solids content and can cause a number ofproblems, primarily plugging and flow distribution issues (dis-cussed later in the "Iron sulfide film removal" section).

Funhermore, some FeS forms are pyrophoric, meaning expo-sure to oxygen can cause them to radiate intense heat and startfires. Plants must be fully clean of FeS (or the internals kept wet)before opening them up to atmosphere. Filters containing FeS anda flammable component are also prone to pyrophoric iron fires ifallowed to dr\' under atmospheric exposure.

Iron sulfide sources. FeS can enter an amine system in theinlet gas or form in the amine system.

Iron sulfîdes entering amine systems with the inlet gas.In many instances, amine plants suffer from FeS ingress in theinlet gas. This can he a problem, since these FeS particles will notreact with the piping walls and add to the protective film; ratherthey will circulate around in solution as suspended solids. Theywill, in effect, scour off the previously formed protective filmscontributing to a greater quantity of suspended solids in solutionas well as to erratic corrosion protection film within the system.Freshly exposed metal surfaces are active sites for the corrosionmechanism to continue.

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The FeS present in the feed ro amine units is rhe by-product ofcorrosion in the wellbore, piping or upstream process equipment,or is produced from the formation itself. Most commonly, corro-sion found in processing equipment is caused by produced watercontaining acid gases—particularly CO2 and H2S.

CO2 corrosion can cake various forms, but it is frequentlyexhibited as localized areas of deep, sharp-sided pits found adja-cent to areas of little corrosion {mesa-r>pe corrosion).

H2S corrosion resuJts In forming black FeS scales and is typi-fied by "black water" in the separation facilities. Under-depositcorrosion frequently occurs beneath the scale layer and can resultin forming deep, isolated or randomly scattered pits.

The three prime means of removing or reducing the impact ofFeS entering an amine system are to;

• Prevent the corrosion from occurring initially in the pipingby using corrosion inhibitors.

• Disperse the FeS particles into the water phase so they canbe removed by inlet separation equipment.

' Filter the FeS from the gas phase upstream ofthe amineabsorber with a Purer element or a water wash.

Iron sulñde formation in the amine system. FeS can form inthe absorber, piping system or rehoiler/regenerator.

In the absorber. Soluble iron ispresent in lean-amine streams. The ironmay be in the form of iron carbonate ininstances where CO? is being treated aswell as H2S. In the absorber, some ofthe HiS immediately reacts with ironin the amine, and small FeS particlesare formed. These particles are generallyinsoluble in amine, and provided theyare large enough, can be filtered out.Fresh or clean amines have the abilityto hold approximately 5 ppm of solubleiron in solution.

An FeS scale will form on the absorber walls and tray decks aswell, if they are made of carbon steel. The scale near the absorberbottom tends to be stronger and thicker due to higher partial pres-sures of FÍTS in this area. Near the absorber top, most ofthe H2Shas been removed from the gas by the amine solution, resultingin very low H2S partial pressures. Scale formation In this area iscomposed mainly of mackinawite.

In the piping. Both the rich and lean amine will have FijSin solution, however, the rich side obviously will have a muchhigher amount. H2S will react immediately with iron ifthe twomeet. When H2S in the liquid or vapor phase contacts the ironin the piping and vessel walls, the FeS particles subsequentlyformed tend to adhere to the metal surface, and if enough H2Sis present, form a strong protective layer over time. Higher H2Spartial pressures result in higher tendencies for strong FeS filmsto form. Piping has been found to have as much as 60% of rhecross-sectional area plugged with FeS in facilities with many yearsof active service at high H2S partial pressures.

When the H2S partial pressure is low, the resulting FeS is nor-mally mackinawite. Mackinawite does not iorm a strong adhesiveprotective layer on the piping; instead it is preferentially carried bythe solution and moves along with the amine resulting in lean/richexchanger plugging as well as other associated problems.

FeS films are stronger and thicker in plant areas where H2Spartial pressure is the highest. This ¡s typically the rich piping

• Once formed, it is generally

desirable to leave the FeS film

on the amine plant internals.

Once liberated, the suspended

FeS particles can result in several

problems.

between the absorber and flash tank. As system pressure or Fl2Scontent in the amine decreases, so does the FeS film thickness andquality. At the same time, because there is very little Fi S partialpressure, there is generally less need for protection, provided diereis no significant CO2 content or agressive organic acid level ineither the solution or the vapor phase.

In tbe reboiler/regenerator. In the regenerator tower lowersection and in the reboiler, H2S partial pressures are extremelylow; FeS formation as a result of H2S is minimal. Elemental sul-fur, however, which enters a plant bonded with H2S as hydrogenpolysulfide (H^S^), is liberated when the H2S is driven off and isno longer soluble in the amine .solution. Elemental sulfur reactsquickly with iron to form pyrite, which is the predominant scalefotmd in this area.

If H2S remains in solution at this point, ihe usual FeS reactionwill still occur but due to the high temperatures driving the reac-tion, the FeS formed will be pyrrhodte or pyrite.

Removing an iron suif ide f iim. Once formed, it is gener-ally desirable to leave the FeS film on the amine plant internals.This film can be removed accidentally, however, and it is impor-

tant for engineers and operators to beaware ofthe accidental removal causes:

• High fluid velocity• Excessive vibration• Mechanical/thermal shocks during

startup/shut down• Heat-stable salt degradation prod-

ucts (increased suspended solids erodethe FeS layer)

• Chelating agents present in theliquid phase

• Adding a corrosion inhibitor tothe system without understanding theinhibitors protection mechanism.

Once liberated, the suspended FeSparticles can result in several problems:

• Amine foaming—results ¡n ofF-spec. gas and tendency tocarryover

> Rather then cause a soludon 10 foam, sohds tend to sta-bilize an already foaming condition

• Excessive mechanical wear on pumps and seals; lost effi-ciency and higher maintenance frequency

• Lost amine efficiency—curtailing throughput• Higher chemical use/costs—(i.e., andfoam, corrosion inhib-

itors, etc.)• Abrasion—the suspended FeS erodes the exisdng FeS film

in other areas• Excessive particle filter plugging and usage• Packing, tray valve or sieve hole plugging.High fluid velocity—The FeS particles that have formed

between H2S in the liquid phase and iron in the piping walls maybe under such high drag forces that they cannot adhere to thepiping walls. With no protective film, fresh iron is exposed thatwill also react with H2S.

Fluid velocity depends on piping diameter. In cases whereamine circulation rate is to be significantly increased, it is recom-mended pipe internal diameters are double-checked to ensurethe fluid velocities do not get too high. It is generally recognizedthat in amine service a maximum fluid velocity of 6 ft/sec (2 m/s)will prevent significant erosion-related protective film removal

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CORROSION/MAINTENANCE

FeS will turn an amine from light yellow to green to brown or black.

for carbon stee! piping. This velocity may be as low as 3 ft/sec ( 1m/s) in exchanger tubes.

Excessive vibration—Suon^ FeS films are quite rigid and cancrack and break loose if the pipe begins to vibrate excessively. Thiscan be a result of piping supports coming loose, excess hydrocar-bon and acid gas flashing, or pressure drops across pressure-reliefvalves being increased.

Excessive vibration is normally associated with high heat fluxin the reboiler tubes (greater than 7400 Btu/hr/ft').

Startup/shut down shocks—It is common for plants to experi-ence filter plugging Immediately after starting an amine system,even if it was only shut down for a few minutes. This is commonlyreferred to as an "upset" and much like excessive vibration, sud-den surges, pushes and pulls, and thermal shocks displace the FeSlayer from piping walls. Tbe particles knocked loose are large andeasily picked up by filters. They can also plug off other pieces ofequipment.

Increase in heat-stable amine salt levels—Solubility of mostFeS in the amine solution (pyrite being the exception) increasesas pH decreases, or becomes more acidic. The pH can changefora number of reasons: an increase in loading (HiS and COi),change in amine type or strength, or heat-stable salt build-up. FeSformed at pH levels below 8.5 are known to be much less effectiveat adhering strongly to piping walls.

pH reductions are normally brought about by the build-up ofheat-stable amine salts. The negative effects of low pH ate foundmost predominantly in high-temperature areas. As pH drops, theexisting FeS film will soften as anions From the acid will react withthe iron portion of the FeS. If allowed to continue, the FeS filmis eventually removed.

Chelating agents present—chelating, or iron compleîdng agentssuch as cyanide, thiocyanate, EDFA, bicine, certain degradationproducts, etc., will act to dissolve the otherwise insoluble FeSinto solution. Amines are capable of holding much more iron ifchelating agents are in the solution. With no chelants, amine canonly hold up to 5 ppm iron.

The effects of cyanide and ammonia can be especially disas-trous. Years ago, significant hydrogen blistering in amine unitswas being experienced in refmeries. Research into the cause of thehydrogen attack revealed that the protective FeS layer is removedby free cyanide as follows:

2^ (4)

Ammonium ferrocyanide is water soluble, thus the protectivesurface layer is removed, exposing additional metal to bisulfideand H2S attack.

Filtering iron s u l f i d e s . Once a protective layer is formed,excessive FeS should be filtered out of the amine solution.When initially formed, FeS particles are typically 0.5-5 |Jm.If the plant is not utilizing filters small enough to removeparticles of this size, the FeS particles will not get filtered outuntil they adhere to one another and form larger particles.

Most amine systems have particle filtration installed on the leanside. When these filters are changed they tend to be black, and whenanalyzed found that tbe filtrate is predominandy FeS. It is clear FeSexists on the lean side; however, the vast majority of FeS in an aminesystem is present on the rieb side. As described earlier, FeS is eitherintroduced into the system via the inlet gas or formed when H2Sreacts with iron. If the solids remain in solution and do not precipi-tate OUI in rhe lean/rich exchanger or contribute to an existing FeSfilm, they are carried into the regenerator where much of the H2S isdriven off, thus liberating the Fe* ion. Sometimes these ions will reactwith any remaining CO2 to form iron carbonate (which is predomi-nandy soluble in amine), at higher temperatures (>80''C/176°F)magtietite can form, or they simply remain firee iron ions.

When the amine reaches tbe absorber again, the H2S will reaawith any free iron available as well as iron carbonate to reform FeS.If the FeS formed in the absorber does not adhere to the vessel orpipe walls, it moves along In solution as stispended solids.

Rich filtration is necessary when the FeS in the absorber andrich piping do not form a protective film, but rather become sus-pended solids in the amine. Many plants with no rich filtrationhave found out the lean/rich exchanger or upper regenerator trayswill act as filters instead! Whether the FeS will form a protectivefilm is determined by several things, the most important of whichbeing the H2S partial pressure, the solution pH and the overallsolution quality, ln our experience, plants that have rich-amineHjS partial pressures between 103 kPa (15 psig) and 0.7 kPa (0.1psig) require rich filtration.

HYDROCARBON PROCESSING MARCH 2010 53

CORROSION/MAINTENANCE

In general, the FeS seen in rich filters is mackinawice, the weak-est FeS form and most commonly guilty of pluming equipment.On the lean side, both mackinawite and pyrite can be found inthe filters. Pyrite forms in the reboiler and regenerator bottom. Itinitially adds to the protective film on die vessel walls, but is britdeand can break off. It is not soluble in amine and, therefore, is car-ried in solution and picked up in the lean filters. Mackinawite canalso form on the lean side due to the slight HiS partial pressureoften left in the amine.

In typical amine systems, a 5- or lO-micron absolute ratedparticle filter is recommended on the lean side. Ideally, filters lastapproximately two weeks before needing to be changed out. Thefilter change frequency will vary from iacilit)' to facility.

FeS will turn an amine from light yellow to pale green to darkgreen to brown to black (Fig. 1). Soluble metal salts are knownto cause solution color changes due to their ability to affect lightdiffraction. It is common to see a green-colored rich amine andthe lean solution from the same system is yellow. This is due to therelative absence of FeS in the lean solution compared to the richsolution. Laboratory experiments have been carried out in whichthe lean solution has changed from a pale yellow color with novisible particles to a dark green solution with visible solids simplyby bubbling small amounts of H2S into the solution.

Before shut d o w n . At one time or another, most refineriesand gas plants experience spontaneous FeS ignition either on theground or inside equipment. When this occurs inside equipmentlike columns, vessels, tanks, exchangers and filters containingresidual hydrocarbons and air, the results can be devastating. Mostcommonly, pyrophoric iron fires occur during shut downs whenequipment and piping are opened for inspection or maintenance.Instances of fires in crude columns during turnarounds, explosionsin suiftir, crude or asphalt storage tanks, overpressures in vessels,etc.. due to pyrophoric iron ignition is not uncommon.

Wlien FeS is oxidized, this is an exothermic reaction where theproducts are iron oxide, free suliôir or SOi plus heat. The heat is sointense that surrounding FeS particles become incandescent andwill ignite any nearby flammable source (usually a hydrocarbon/warer mixture). If there is nothing nearby to ignite, the heat dis-sipates very quickly.

The reaction process is:Initially, FeS is formed in the system:

Fe,O, (rust) + 3H,S^2FeS + 3H.

When exposed to air:4 F e S + 3 O , ^ 2Fe2

4FeS + 7O2 -> 2Fe

3 + 4S + heat

-f heat

(6)

(7)

(8)

FeS fires can be hard to detect since the smoke from SOj iswhite and looks like steam.

Because of the pyrophoric nattire of FeS, it is important thatas much FeS as possible is removed from the system before vesselentry, and even then the area should be kept clear of combu.stibles.FeS poses the largest risk when allowed to dry out, and especiallywhen in the form ofa fine powder (maximizes surface-to-airratio). Mackinawite, being the most unstable of the FeS types seenin amine plants, oxidizes the easiest. Mackinawite is found In areasof low HiS partial pressure and temperature such as che uppersection of a contactor or cool lean piping. Pyrite is the most stableFeS form, and as stich does not oxidize nearly as readily. Pyrite, infact, is found abundantly throughout the world in exposed geo-

logical formations and is not being oxidized. Pyrite samples canbe taken out of an amine plant with little risk involved.

The pyrophoric nature of mackinawite is also responsible forthe spontaneous ignition of spent filter cartridges that are left inthe sun or in the open air. Once the cartridges dry, there is a goodchance the FeS will cause the filter to ignite. This is important toremember not only while the filters are on the plant site but alsowhile being transported to the disposal area. Some facilities utilizesteel boxes open to atmosphere to store used filters. This allowsthe FeS to oxidize to iron oxide without igniting anything on fire.Remember though, SO^ is released during the transformation.

System preparation for inspection. Several approachesto removing FeS scale are:

' Simple acid cleaning" Simple strong ba.se cleaning• Chemical oxidization• Acid or oxidizing cleaning plus additives for H2S suppression• Noentry vessel cleaning (hurricane balls, etc.)• Mechanical.Chemical cleaning, in general, is the most effective method

of FeS removal both in terms of percent FeS removal and cost.Costs can be elevated, however, if cleaning chemical disposal isinconvenient, plus a greater amount of engineering and planningmust be spent on the program. The personnel involved ¡n chemi-cal cleaning should be well educated and familiar with the process.If done improperly, chemical cleaning can cause severe corrosionto amine plant internals. HP

BIBLIOGRAPHYCanfield. C, D.. "Amine System Cleaning Bcsc Practice." Regional Mcciing ol ihc Permian

Basin Gai ProcesM»rs Association.Claassen, IÍ, J.. "Iron Sulfide Prccipliaicd as a Scale in Sour Gas Wells." Proceedings ol the

19861 jinadiiiii Region Wcsicm Conference - NACt. t Jlgary. AB.Craig, B-, "Corrwion I'riMluct Analysis—A Road Map lo Corrosion in Oil and Cas Produc-

tion," Miturials PerjoTtnanic, August 2002.Cudunings. A.. "Inrcicasinc Profitability and Intiproving Environmental Perfrirmance by Main-

[aliung Amine Solvcnr Purity," Protectiingî iif tilt 2000 Laurcntc Reid tij.s t^oniliriotiingConfcrciUJc, Nortnan. Oklahotna.

Cummiiig!,. Al and N. HatLlier. "Amine Sam pi ing/Laboratory Technique Jiid its tffecrs t>nH.S Loading Meitiuremcnts," Proceedings of (he Z005 Laurence Reid Gas ConditioningConference. Norman, Oklaboma.

Husa, E. M., "Intemxl Corrtwion of Offshore Pipelines,' Norwegian Insritute of Technol-ogy-

Keller. A., S. Mecum. R. Kdmmillet. F. Vcntoi. .A. CummingsandJ. Oiompscn, "Hcai-StableSalt Removal From Amints by ihe HSSX Process Using fon F.Kchajiae," Proceedings of ihe1992 Laurence Reid Clas Condilionitig Conference, Norman. Üklaiioma.

Lawson, M.. L Martin and G.Arnold, "Chcmiol Cleaning of FcS Scales," National Associa-tion oí Corro.sion Engineers.

Pauley, C. R. and R. Hashemi, "Analysis of Foaming Mechanisms in Amine Plants." Proceed-ings of tbe 19S') Laurence Reid Gas Conditioning Conference, Nornian. Oklahuma.

Tcwari, P. H., G. Walbte and A. B. Campbell. 'The Solubilir)' of Iron Sulphides andTbeirRoll in Mass Transport in Girdlcr-Sufphide Heavy Water Plants," \XTiiteshet! NuclearResearch Esublishment.

Travis Chemicalï R&D Laboratory, "Revic-w on the Chemisliy, Propenies, and I'hermody-tiamics of Iron Sulphides." AuguM !99'i.

Ward. J. t",, "The Siructure and t'roperties of Some Iron Sulphides." Commonwealth Scien-tific and Industrial Research Organiiatitm,

Clark. P. Private correspondence; .\lbetta Sulphur Research.Spooner. B.. M, Sheilati, D. Street ar»d E. van Hoom. "Sulphides—Friend or Foe?," originally

presented .it thr I jiurtnce Reid conference.

Ben Spooner , P. E., has speni the past decade troubleshooting:)!id optimizing amine plants woridwide. He specializes in amineplant optimization and operator training.

M i k e Shei lan . P E., has been involved in several aspects of thenatural gas processing industry, primarily in relation to the chemi-cals used to treat gas and the proœss« that use these chemicalsduring his 30-yeai career.

MARCH 2010 HYDROCARBON PROCESSING

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