ASTM G205-10
(Guide)Standard Guide for Determining Corrosivity of Crude Oils
Standard Guide for Determining Corrosivity of Crude Oils
SIGNIFICANCE AND USE
In the absence of water, the crude oil is noncorrosive. The presence of sediment and water makes crude oil corrosive. Test Methods , , , and provide methods for the determination of the water and sediment content of crude oil.
The corrosivity of crude oil containing water can be determined by a combination of three properties (Fig. 1) (1) : 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.
Water and oil are immiscible but, under certain conditions, they can form emulsion. There are two kinds of emulsion: O/W and 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 (see ISO 6614) (2). The conductivities of various liquids are provided in Table 1(3). 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.
Whether water phase can cause corrosion in the presence of oil depends on whether the surface is oil wet (hydrophobic) or water wet (hydrophilic) (4-8). 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 the conductivity (spreading method).
In the contact angle method, the tendency of water to displace hydrocarbon from steel is measured directly by observing the behavior of the three phase system. The 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 action will result in an energy decrease of the system. To determine whether the ...
SCOPE
1.1 This guide presents some generally accepted laboratory methodologies that are used for determining the corrosivity of crude oil.
1.2 This guide does not cover detailed calculations and methods, but rather a range of approaches that have found application in evaluating the corrosivity of crude oil.
1.3 Only those methodologies that have found wide acceptance in crude oil corrosivity evaluation are considered in this guide.
1.4 This guide does not address the change in oil/water ratio caused by accumulation of water at low points in a pipeline system.
1.5 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.
1.6 This guide does not cover the evaluation of corrosivity of crude oil at higher temperatures (typically above 300°C) that occur during refining crude oil in refineries.
1.7 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.
1.8 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.9 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 and health practices and determine the applicability of regulatory limitations prior to use.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: G205 − 10
Standard Guide for
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Determining Corrosivity of Crude Oils
This standard is issued under the fixed designation G205; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This guide presents some generally accepted laboratory
methodologies that are used for determining the corrosivity of
2. Referenced Documents
crude oil.
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2.1 ASTM Standards:
1.2 This guide does not cover detailed calculations and
D96 Test Method for Water and Sediment in Crude Oil by
methods, but rather a range of approaches that have found 3
Centrifuge Method (Field Procedure) (Withdrawn 2000)
application in evaluating the corrosivity of crude oil.
D473 Test Method for Sediment in Crude Oils and Fuel Oils
1.3 Only those methodologies that have found wide accep- by the Extraction Method
tance in crude oil corrosivity evaluation are considered in this D665 Test Method for Rust-Preventing Characteristics of
guide. Inhibited Mineral Oil in the Presence of Water
D724 Test Method for Surface Wettability of Paper (Angle-
1.4 Thisguidedoesnotaddressthechangeinoil/waterratio
3
of-Contact Method) (Withdrawn 2009)
caused by accumulation of water at low points in a pipeline
D1125 Test Methods for Electrical Conductivity and Resis-
system.
tivity of Water
1.5 This guide is intended to assist in the selection of
D1129 Terminology Relating to Water
methodologies that can be used for determining the corrosivity
D1141 Practice for the Preparation of Substitute Ocean
of crude oil under conditions in which water is present in the
Water
liquid state (typically up to 100°C). These conditions normally
D1193 Specification for Reagent Water
occurduringoilandgasproduction,storage,andtransportation
D4006 Test Method for Water in Crude Oil by Distillation
in the pipelines.
D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.6 This guide does not cover the evaluation of corrosivity
ofcrudeoilathighertemperatures(typicallyabove300°C)that D4377 Test Method forWater in Crude Oils by Potentiomet-
ric Karl Fischer Titration
occur during refining crude oil in refineries.
G1 Practice for Preparing, Cleaning, and Evaluating Corro-
1.7 This guide involves the use of electrical currents in the
sion Test Specimens
presence of flammable liquids. Awareness of fire safety is
G31 Guide for Laboratory Immersion Corrosion Testing of
critical for the safe use of this guide.
Metals
1.8 The values stated in SI units are to be regarded as
G111 Guide for Corrosion Tests in High Temperature or
standard. No other units of measurement are included in this
High Pressure Environment, or Both
standard.
G170 Guide for Evaluating and Qualifying Oilfield and
1.9 This standard does not purport to address all of the Refinery Corrosion Inhibitors in the Laboratory
safety concerns, if any, associated with its use. It is the G184 Practice for Evaluating and Qualifying Oil Field and
responsibility of the user of this standard to establish appro- Refinery Corrosion Inhibitors Using Rotating Cage
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
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This guide is under the jurisdiction ofASTM Committee G01 on Corrosion of contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Metals and is the direct responsibility of Subcommittee G01.05 on Laboratory Standards volume information, refer to the standard’s Document Summary page on
Corrosion Tests. the ASTM website.
3
Current edition approved Sept. 1, 2010. Published October 2010. DOI: 10.1520/ The last approved version of this historical standard is referenced on
G0205–10. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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G205 − 10
G193 Terminology and Acronyms Relating to Corrosion 4.4 The corrosiveness of water phase in the presence of
G202 Test Method for UsingAtmospheric Pressure Rotating crude oil can be determined using several methods.
Cage
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5. Significance and Use
2.2 ISO Standard:
ISO 6614 Petroleum products—Determination of Water
5.1 In the absence of water, the crude oil is noncorrosive.
Separability of Petroleum Oils and Synthetic Fluids
The presence of sediment and water makes crude oil corrosive.
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2.3 NACE Standard:
Test Methods D96, D473, D4006, and D4377 provide methods
TM0172 Standard Test Method Determining Corrosive
for the determination of the water and sediment content of
Properties of Cargoes in
...
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