ASTM_D_7157_-_12.pdf

Designation:D715712Standard Test Method forDetermination of Intrinsic Stability of Asphaltene-ContainingResidues,Heavy Fuel Oils,and Crude Oils(n-HeptanePhase Separation;Optical Detection)1This standard is issued under the fixed designation D7157;the number immediately following the designation indicates the year oforiginal adoption 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.Scope*1.1 This test method covers a procedure for quantifying theintrinsic stability of the asphaltenes in an oil by an automaticinstrument using an optical device.1.2 This test method is applicable to residual products fromthermal and hydrocracking processes,to products typical ofSpecifications D396 Grades No.5L,5H,and 6,and D2880Grades No.3-GT and 4-GT,and to crude oils,providing theseproducts contain 0.5 mass%or greater concentration of as-phaltenes(see Test Method D6560).1.3 This test method quantifies asphaltene stability in termsof state of peptization of the asphaltenes(S-value),intrinsicstability of the oily medium(So)and the solvency requirementsof the peptized asphaltenes(Sa).1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use2.Referenced Documents2.1 ASTM Standards:2D396 Specification for Fuel OilsD2880 Specification for Gas Turbine Fuel OilsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4175 Terminology Relating to Petroleum,PetroleumProducts,and LubricantsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD4870 Test Method for Determination of Total Sediment inResidual FuelsD6560 Test Method for Determination of Asphaltenes(Hep-tane Insolubles)in Crude Petroleum and Petroleum Prod-uctsD6792 Practice for Quality System in Petroleum Productsand Lubricants Testing Laboratories3.Terminology3.1 Definitions:3.1.1 For definitions of some terms used in this test method,refer to Terminology D4175.3.1.2 asphaltenes,n(rarely used in the singular),in petro-leum technology,represent an oil fraction that is soluble in aspecified aromatic solvent but separates upon addition of anexcess of a specified paraffinic solvent.3.1.2.1 DiscussionIn this test method,the aromatic sol-vent is toluene and the paraffinic solvent is n-heptane.3.1.3 compatibility,nof crude oils or of heavy fuel oils,the ability of two or more crude oils or fuel oils to blendtogether within certain concentration ranges without evidenceof separation,such as the formation of multiple phases.3.1.3.1 DiscussionIncompatible heavy fuel oils or crudeoils,when mixed or blended,result in the flocculation orprecipitation of asphaltenes.Some oils may be compatiblewithin certain concentration ranges in specific mixtures,butincompatible outside those ranges.3.1.4 flocculation,nof asphaltenes from crude oils orheavy fuel oils,the aggregation of colloidally dispersed as-phaltenes into visible larger masses which may or may notsettle.3.1.5 peptization,nof asphaltenes in crude oils or heavyoils,the dispersion of asphaltenes to produce a colloidaldispersion.3.1.6 stability reserve,nin petroleum technology,theproperty of an oil to maintain asphaltenes in a peptized stateand prevent flocculation of asphaltenes.1This test method is under the jurisdiction of Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Nov.1,2012.Published February 2013.Originallyapproved in 2005.Last previous edition approved in 2009 as D715709.DOI:10.1520/D7157-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.6.1 DiscussionAn oil with a low stability reserve islikely to undergo flocculation of asphaltenes when stressed(forexample,extended heated storage)or blended with a range ofother oils.Two oils each with a high stability reserve are likelyto maintain asphaltenes in a peptized state and not lead toflocculation when blended together.3.2 Definitions of Terms Specific to This Standard:3.2.1 intrinsic stability(S-value),n of refinery residualstreams,residual fuel oils and crude oils,an indication of thestability or available solvency power of an oil with respect toprecipita