1、Designation: G205 10G205 16Standard Guide forDetermining Corrosivity Emulsion Properties, WettingBehavior, and Corrosion-Inhibitory Properties of Crude Oils1This standard is issued under the fixed designation G205; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide presents some generally accepted laboratory methodologies that
3、are used for determining the corrosivityemulsion forming tendency, wetting behavior, and corrosion-inhibitory properties of crude oil.1.2 This guide does not cover detailed calculations and methods, but rather covers a range of approaches that have foundapplication in evaluating the corrosivity of c
4、rude oil.emulsions, wettability, and the corrosion rate of steel in crude oil/watermixtures.1.3 Only those methodologies that have found wide acceptance in crude oil corrosivity evaluation the industry are consideredin this guide.1.4 This guide does not address the change in oil/water ratio caused b
5、y accumulation of water at low points in a pipeline system.1.4 This guide is intended to assist in the selection of methodologies that can be used for determining the corrosivity of crudeoil under conditions in which water is present in the liquid state (typically up to 100C). These conditions norma
6、lly occur duringoil and gas production, storage, and transportation in the pipelines.1.5 This guide does not cover the evaluation of corrosivity of crude oil is not applicable at higher temperatures (typically above300C) that occur during refining crude oil in refineries.1.6 This guide involves the
7、use of electrical currents in the presence of flammable liquids. Awareness of fire safety is criticalfor the safe use of this guide.1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.8 This standard does not purport to addr
8、ess all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D96 Test Method
9、for Water and Sediment in Crude Oil by Centrifuge Method (Field Procedure) (Withdrawn 2000)3D473 Test Method for Sediment in Crude Oils and Fuel Oils by the Extraction MethodD665 Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of WaterD724 Test Method for Sur
10、face Wettability of Paper (Angle-of-Contact Method) (Withdrawn 2009)3D1125 Test Methods for Electrical Conductivity and Resistivity of WaterD1129 Terminology Relating to WaterD1141 Practice for the Preparation of Substitute Ocean WaterD1193 Specification for Reagent WaterD4006 Test Method for Water
11、in Crude Oil by DistillationD4057 Practice for Manual Sampling of Petroleum and Petroleum Products1 This guide is under the jurisdiction of ASTM Committee G01 on Corrosion of Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory CorrosionTests.Current edition approved Sept. 1,
12、 2010Nov. 1, 2016. Published October 2010December 2016. Originally approved in 2010. Last previous edition approved in 2010 asG205 10. DOI: 10.1520/G020510.10.1520/G0205-16.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For An
13、nual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an
14、indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to
15、be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D4377 Test Method for Water in Crude Oils by Potentiometric Karl Fischer TitrationG1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test S
16、pecimensG31 Guide for Laboratory Immersion Corrosion Testing of MetalsG111 Guide for Corrosion Tests in High Temperature or High Pressure Environment, or BothG170 Guide for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors in the LaboratoryG184 Practice for Evaluating and Qualifyi
17、ng Oil Field and Refinery Corrosion Inhibitors Using Rotating CageG185 Practice for Evaluating and Qualifying Oil Field and Refinery Corrosion Inhibitors Using the Rotating Cylinder ElectrodeG193 Terminology and Acronyms Relating to CorrosionG202 Test Method for Using Atmospheric Pressure Rotating C
18、age2.2 ISO Standard:4ISO 6614 Petroleum productsDetermination of Water Separability of Petroleum Oils and Synthetic Fluids2.3 NACE Standard:5TM0172 Standard Test Method Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines3. Terminology3.1 DefinitionsThe terminology used herein,
19、 if not specifically defined otherwise, shall be in accordance with terminologiesin Guide G170, Terminology and Acronyms G193, and Terminology D1129. Definitions provided herein and not given interminologies in Guide G170, Terminology and Acronyms G193, and Terminology D1129 are limited only to this
20、 guide.standard.3.2 Definitions of Terms Specific to This Standard:3.2.1 emulsion, na two-phase immiscible liquid system in which one phase is dispersed as droplets in the other phase.3.2.2 emulsion-inversion point, nthe volume percentage of water at which a water-in-oil (W/O) emulsion converts into
21、 anoil-in-water (O/W) emulsion.3.2.3 wettability, ntendency of a liquid to wet or adhere on to a solid surface.3.3 Acronyms:CO2 = Carbon dioxideEIP = Emulsion inversion pointH2S = Hydrogen sulfideKOH = Potassium hydroxideNaCl = Sodium chlorideNa2CO3 = Sodium carbonateNaHCO3 = Sodium bicarbonateNaOH
22、= Sodium hydroxideNa2S = Sodium sulfideO/W = Oil-in-waterW/O = Water-in-oil4. Summary of Guide4.1 This guide describes methodsmethodologies for determining the corrosivitythree properties of crude oils by a combinationof three properties: that are relevant to corrosion processes caused by the presen
23、ce of water in hydrocarbon transport and handling:(1) the emulsion of the oil and water, (2) the wettability of the steel surface, and (3) the corrosivity of water phase in the presenceof oil.4.2 Conductivity of emulsion can be used to determine the type of emulsion: oil in water oil-in-water (O/W)
24、or water in oilwater-in-oil (W/O). The conductivity of the O/W emulsion (in which water is the continuous phase) is high. The conductivity ofthe W/O emulsion (in which oil is the continuous phase) is low.4.3 The wettability of a steel surface is determined using two methods: by either (1)contact ang
25、le method andmethodology or(2)spreading method.methodology.4.4 The corrosiveness of water phase in the presence of crude oil can be determined using several methods.methodologies.5. Significance and Use5.1 In the absence of water, the crude oil is noncorrosive. The presence of sediment and water mak
26、es crude oil corrosive.However, trace amounts of water and sediment have the potential to create corrosive situations during crude oil handling ortransport if such materials accumulate and persist on steel surfaces. Test Methods D96, D473, D4006, and D4377 provide methodsfor the determination of the
27、 water and sediment content of crude oil.4 Available from the American National Standards Institute, 25 W. 43rd St., New York, NY 10036.5 Available from the National Association of Corrosion Engineers, 1440 S. Creek Dr., Houston, TX 77084-4906.G205 1625.2 The corrosivity potential for a corrosive si
28、tuation to develop during the handling and transport of crude oil containing thatcontains water can be determined by a combination of three properties (Fig. 1) (1)6: the type of emulsion formed between oiland water, the wettability of the steel surface, and the corrosivity of water phase in the pres
29、ence of oil.5.3 Water and oil are immiscible but, under certain conditions, they can form emulsion. There are two kinds of emulsion: O/Wand W/O. oil-in-water (O/W) and water-in-oil (W/O). W/O emulsion (in which oil is the continuous phase) has low conductivityand is thus less corrosive; whereas O/W
30、(in which water is the continuous phase) has high conductivity and, hence, is corrosive(see ISO 6614) (2). The conductivities of various liquids are provided in (see ISO 6614). The Table 1(3). The percentage of water6 The boldface numbers in parentheses refer to a list of references at the end of th
31、is standard.FIG. 1 Predicting Influence of Crude Oil on the Corrosivity of Aqueous PhaseG205 163at which W/O converts to O/W is known as the emulsion inversion point (EIP). EIP can be determined by measuring theconductivity of the emulsion. At and above the EIP, a continuous phase of water or free w
32、ater is present. Therefore, there is apotential for corrosion.5.4 Whether water phase can cause corrosion in the presence of oil depends on whether the surface is oil wet oil-wet(hydrophobic) or water wet water-wet (hydrophilic) (1, 4-3-58).). Because of higher resistance, an oil-wet surface is nots
33、usceptible to corrosion, but a water-wet surface is. Wettability can be characterized by measuring the contact angle or theconductivity (spreading method).by evaluating the tendency of water to displace oil from a multi-electrode array by measuring theresistance (or conductors) between the electrode
34、s (spreading methodology).5.4.1 In the contact angle method,methodology, the tendency of water to displace hydrocarbon from steel is measured directlyby observing the behavior of the three phase system. The contact angle determined by direct observation of the contact angle thatresults when both oil
35、 and water are in contact with the steel. Although this contact angle is determined by the surface tensions(surface free energies) of the three phases. A hydrocarbon-steel interface will be replaced by a water-steel interface if this actionwill result in an energy decrease of the system. To determin
36、e whether the surface is oil wet, mixed wet, or water wet, the angleat the oil-water-solid intersection is observed and measured.interfacial free energies of the phases involved, there is no standardmethod to determine the steel-oil or steel-water interfacial free energies.5.4.2 In the spreading met
37、hodmethodology of determining wettability, the resistance between isolated steel pins is measured.If a conducting phase (for example, water) covers (wets) the distance between the pins, conductivity between them will be high.On the other hand, if a nonconductingIf a non-conducting phase (for example
38、, oil) covers (wets) the distance between the pins,the conductivity between them will be low.5.5 Dissolution of ingredients from crude oils may alter the corrosiveness of the aqueous phase. Based A crude oil can beclassified as corrosive, neutral, or inhibitory based on how the corrosivity of the aq
39、ueous phase changes in its presence, a crudeoil can be classified as corrosive, neutral, inhibitory, or preventive crude. Corrosiveness of the is altered by the presence of the oil.Corrosiveness of aqueous phase in the presence of oil can be determined by methods described in Test Method D665, Guide
40、 G170,Practice G184, Practice G185, Test Method G202, and NACE TM0172.6. Materials6.1 Methods for preparing coupons and probes for tests and for removing coupons after the test are described in Practice G1.Standard laboratory glassware should be used for weighing and measuring reagent volumes.6.2 Th
41、e coupons/probes should be made of the field material (such as carbon steel) and have the same metallographic structureas that used in the service components. The probes for wettability and EIP measurements should be ground to a surface finish of600 grit. Preparation of coupons for corrosion measure
42、ments is described in Guide G170, Practice G184, Practice G185, and TestMethod G202.7. Preparation of Test Solutions7.1 Oil should be obtained from the field that is being evaluated. Practice D4057 provides guidelines for collecting crude oil.It is important that live fluids do not contain externall
43、y added contaminants, for example, corrosion inhibitors, biocides, andsurfactants. surfactants to allow measurement of Guide G205 parameters on the “base” crude. A water sample should also beobtained from the field. A synthetic aqueous solution could be used; the composition of which, however, which
44、 should be basedon field water analysis.Alternatively, standard 3 % brine use of 3 % NaCl aqueous solution composed of purified water and reagentgrade sodium chloride or synthetic brine (ofof a composition provided in Practice D1141) (substitute ocean water, note brinestability is approximately one
45、day) may be used. Their composition should be specified in the work plan and recorded in thelaboratory logbook. The solutions should be prepared following good laboratory practice. The solutions should be prepared usingreagents (in accordance with Test Method G202) and deionized water (in accordance
46、 with Specification D1193).7.2 The solutions (oil and water phases) should be deaerated by passing nitrogen (or any other inert gas) and kept underdeaerated conditions. Solutions should be transferred with minimal contact with air. Procedures to transfer the solutions aredescribed in Test Method G20
47、2.7.3 Procedures to deoxygenate and saturate the solutions with acid gases are presented in Test Method G202. To simulate fieldoperating conditions, the solution is often required to be saturated with acid gases such as hydrogen sulfide (H2S) and carbondioxide (CO2). H2S and CO2 are corrosive gases.
48、 H2S is poisonous and shall not be released to the atmosphere. The appropriatecomposition of gas can be obtained by mixing H2S, CO2, and methane streams from the standard laboratory gas supply. Nitrogenor any other inert gas can be used as a diluent to obtain the required partial pressures of the co
49、rrosive gases. Alternatively, gasmixtures of the appropriate compositions can be purchased from suppliers of industrial gases. The composition of gas depends onthe field gas composition. The oxygen concentration in solution depends on the quality of gases used to purge the solution. Theoxygen content of nitrogen or the inert gas should be less thenthan 10 ppm by volume. LeaksAny leaks through the vessel, tubing,and joints should be avoided.7.4 The test vessels should be heated slowly to avoid overheating. The thermostat in the heater or thermostatic bath should bese
