1.1 本指南涵盖了一些公认的实验室方法，这些方法用于确定原油的乳液形成趋势、润湿行为和防腐性能。 1.2 本指南不包括详细的计算和方法，而是涵盖了一系列方法，这些方法已被应用于评估原油/水混合物中钢的乳液、润湿性和腐蚀速率。 1.3 本指南只考虑那些在行业中被广泛接受的方法。 1.4 本指南旨在帮助选择可用于确定在液态水（通常高达100 °C）。 这些情况通常发生在管道中的石油和天然气生产、储存和运输过程中。 1.5 本指南不适用于更高的温度（通常高于300 °C）。 1.6 本指南涉及在存在易燃液体的情况下使用电流。消防安全意识对于安全使用本指南至关重要。 1.7 以国际单位制表示的数值应视为标准。本标准不包括其他计量单位。 1.8 本标准并不旨在解决与其使用相关的所有安全问题（如有）。 本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.9 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 在无水的情况下，原油是无腐蚀性的。然而，在原油处理或运输过程中，如果这些物质积聚并持续存在于钢表面，微量的水和沉积物有可能产生腐蚀性情况。试验方法 D473 和 D4006 提供了测定原油中水分和沉积物含量的方法。 5.2 在处理和运输含有水的原油过程中，腐蚀情况的可能性可由三种特性的组合确定( 图1 ) ( 1. ) 6. :油和水之间形成的乳液类型，钢表面的润湿性，以及油存在时水相的腐蚀性。 图1 原油对水相腐蚀性影响的预测 5.3 水和油是不混溶的，但在某些条件下，它们可以形成乳液。乳液有两种:水包油型（O/W）和油包水型（W/O）。W/O乳液（其中油是连续相）具有低电导率，因此腐蚀性较小；而O/W（其中水是连续相）具有高导电性，因此具有腐蚀性 ( 2. ) （参见ISO 6614）。W/O转化为O/W的水的百分比称为乳液转化点（EIP）。EIP可以通过测量乳液的电导率来确定。在EIP及其上方，存在连续的水或自由水相。因此，存在腐蚀的可能性。 5.4 水相在油的存在下是否会引起腐蚀取决于表面是油湿的（疏水的）还是水湿的（亲水的） ( 1. , 3- 5. ) 。由于电阻较高，油湿表面不易腐蚀，但易受水腐蚀- 润湿性可以通过测量接触角来表征，或者通过测量电极之间的电阻（或导体）来评估水从多电极阵列中驱油的趋势（扩展方法）。 5.4.1 在接触角法中，水从钢中置换碳氢化合物的趋势是通过直接观察油和水与钢接触时产生的接触角来确定的。尽管这个接触角是由相关相的界面自由能决定的，但没有标准的方法来确定钢- 油或钢-水界面自由能。 5.4.2 在确定润湿性的铺展方法中，测量了隔离钢销之间的电阻。如果导电相（例如水）覆盖（润湿）引脚之间的距离，则引脚之间的导电性将很高。如果非导电相（例如油）覆盖（润湿）引脚之间的距离，则引脚之间的导电性将较低。 5.5 原油中成分的溶解可能会改变水相的腐蚀性。根据油的存在如何改变水相的腐蚀性，原油可以分为腐蚀性或抑制性。 油存在下水相的腐蚀性可通过试验方法中所述的方法进行测定 D665 指导 G170 实践 G184 实践 G185 ，试验方法 G202 和NACE TM0172。

1.1 This guide covers some generally accepted laboratory methodologies that are used for determining emulsion 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 found application in evaluating emulsions, wettability, and the corrosion rate of steel in crude oil/water mixtures. 1.3 Only those methodologies that have found wide acceptance in the industry are considered in this guide. 1.4 This guide is intended to assist in the selection of methodologies that can be used for determining the corrosivity of crude oil under conditions in which water is present in the liquid state (typically up to 100 °C). These conditions normally occur during oil and gas production, storage, and transportation in the pipelines. 1.5 This guide is not applicable at higher temperatures (typically above 300 °C) that occur during refining crude oil in refineries. 1.6 This guide involves the use of electrical currents in the presence of flammable liquids. Awareness of fire safety is critical for 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 address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 In the absence of water, the crude oil is noncorrosive. However, trace amounts of water and sediment have the potential to create corrosive situations during crude oil handling or transport if such materials accumulate and persist on steel surfaces. Test Methods D473 and D4006 provide methods for determination of the water and sediment content of crude oil. 5.2 The potential for a corrosive situation to develop during the handling and transport of crude oil that contains water can be determined by a combination of three properties ( Fig. 1 ) ( 1 ) 6 : the type of emulsion formed between oil and water, the wettability of the steel surface, and the corrosivity of water phase in the presence of oil. FIG. 1 Predicting Influence of Crude Oil on the Corrosivity of Aqueous Phase 5.3 Water and oil are immiscible but, under certain conditions, they can form emulsion. There are two kinds of emulsion: oil-in-water (O/W) and water-in-oil (W/O). W/O emulsion (in which oil is the continuous phase) has low conductivity and is thus less corrosive; whereas O/W (in which water is the continuous phase) has high conductivity and, hence, is corrosive ( 2 ) (see ISO 6614). The percentage of water at which W/O converts to O/W is known as the emulsion inversion point (EIP). EIP can be determined by measuring the conductivity of the emulsion. At and above the EIP, a continuous phase of water or free water is present. Therefore, there is a potential for corrosion. 5.4 Whether water phase can cause corrosion in the presence of oil depends on whether the surface is oil-wet (hydrophobic) or water-wet (hydrophilic) ( 1 , 3- 5 ) . Because of higher resistance, an oil-wet surface is not susceptible to corrosion, but a water-wet surface is. Wettability can be characterized by measuring the contact angle or by evaluating the tendency of water to displace oil from a multi-electrode array by measuring the resistance (or conductors) between the electrodes (spreading methodology). 5.4.1 In the contact angle methodology, the tendency of water to displace hydrocarbon from steel is determined by direct observation of the contact angle that results when both oil and water are in contact with the steel. Although this contact angle is determined by the interfacial free energies of the phases involved, there is no standard method to determine the steel-oil or steel-water interfacial free energies. 5.4.2 In the spreading methodology 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. If a non-conducting phase (for example, 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. A crude oil can be classified as corrosive or inhibitory based on how the corrosivity of the aqueous phase 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 G170 , Practice G184 , Practice G185 , Test Method G202 , and NACE TM0172.