ASTM_E_1928_-_13.pdf

Designation:E192813Standard Practice forEstimating the Approximate Residual Circumferential Stressin Straight Thin-walled Tubing1This standard is issued under the fixed designation E1928;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 A qualitative estimate of the residual circumferentialstress in thin-walled tubing may be calculated from the changein outside diameter that occurs upon splitting a length ofthin-walled tubing.This practice assumes a linear stressdistribution through the tube wall thickness and will notprovide an estimate of local stress distributions such as surfacestresses.(Very high local residual stress gradients are commonat the surface of metal tubing due to cold drawing,peening,grinding,etc.)The Hatfield and Thirkell formula,as latermodified by Sachs and Espey,2provides a simple method forcalculating the approximate circumferential stress from thechange in diameter of straight,thin-walled,metal tubing.1.2 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 use.2.Referenced Documents2.1 ASTM Standards:3E6 Terminology Relating to Methods of Mechanical Testing3.Terminology3.1 The definitions in this practice are in accordance withTerminology E6.4.Significance and Use4.1 Residual stresses in tubing may be detrimental to thefuture performance of the tubing.Such stresses may,forexample,influence the susceptibility of a tube to stress corro-sion cracking when the tube is exposed to certain environ-ments.4.2 Residual stresses in new thin-walled tubing are verysensitive to the parameters of the fabrication process,and smallvariations in these parameters can produce significant changesin the residual stresses.See,for example,Table 1,which showsthe residual stresses measured by this practice in samples fromsuccessive heats of a ferritic Cr-Mo-Ni stainless steel tube anda titanium condenser tube.This practice provides a means forestimating the residual stresses in samples from each and everyheat.4.2.1 This practice may also be used to estimate the residualstresses that remain in tubes after removal from service indifferent environments and operating conditions.4.3 This practice assumes a linear stress distribution throughthe wall thickness.This assumption is usually reasonable forthin-walled tubes,that is,for tubes in which the wall thicknessdoes not exceed one tenth of the outside diameter.Even incases where the assumption is not strictly justified,experiencehas shown that the approximate stresses estimated by thispractice frequently serve as useful indicators of the suscepti-bility to stress corrosion cracking of the tubing of certain metalalloys when exposed to specific environments.4.3.1 Because of this questionable assumption regarding thestress distribution in the tubing,the user is cautioned againstusing the results of this practice for design,manufacturingcontrol,localized surface residual stress evaluation,or otherpurposes without supplementary information that supports theapplication.4.4 This practice has primarily been used to estimate re-sidual fabrication stresses in new thin-walled tubing between19-mm(0.75-in.)and 25-mm(1-in.)outside diameter and1.3-mm(0.05-in.)or less wall thickness.While measurementdifficulties may be encountered with smaller or larger tubes,there does not appear to be any theoretical size limitation onthe applicability of this practice.5.Procedure5.1 On new material,the stress determination shall be madeon at least one representative sample obtained from each lot orheat of material in the final size and heat treatment.The results1This practice is under the jurisdiction ofASTM Committee E28 on MechanicalTesting and is the direct responsibility of Subcommittee E28.13 on Residual StressMeasurement.Current edition approved Nov.1,2013.Published January 2014.Originallyapproved in 1998.Last previous edition approved in 2007 as E192807.DOI:10.1520/E1928-13.2Sachs,G.and Espey,G.,“A New Method for Determination of StressDistribution in Thin-walled Tubing,”Transactions of the AIME,Vol 147,1942.3For 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 of tests on brass and steel tubes,reported by Sachs and Espey,2indicate that the length of the sample piece of tu