_API_TR_6AM-1995.pdf

Technical Report onMaterial ToughnessAPI 6AMSECOND EDITION.SEPTEMBER 1,1995(FORMERLY BULLETIN 6AM)American Petroleum Institute1220 L Street,NorthwestWashington,D.C.20005FOREWORDThis technical report is under the jurisdiction of the API Subcommittee on Valves andWellhead Equipment.It is a report of the methodology and conclusions of a task groupstudy of material toughness requirements for equipment covered by API Specification 6A.Specification for Wellhead and Christmas Tree Equipment.The report was first issued asAPI Bulletin 6AM,First Edition,September 1,1989,and was reaffirmed and reissued in1995 as a technical report designated API 6 AM.This document was produced solely for the purpose of disseminating technical infor-mation and is not an API standard.API publications may be used by anyone desiring to doso.Every effort has been made by the Institute to assure the accuracy and reliability of thedata contained in them;however,the Institute makes no representation,warranty or guar-antee in connection with this publication and hereby expressly disclaims any liability orresponsibility for loss or damage resulting from its use or for the violation of any federal,state,or municipal regulation with which this publication may conflict.Suggested revisions are invited and should be addressed to the director of the Explo-ration and Production Department,American Petroleum Institute,1220 L Street,N.W.,Washing ton,D.C.20005.This publication shall become effective on the date printed on the cover but may be usedvoluntarily from the date of distribution.SUMMARYCVN toughness requirements can be used as a quality assurance measure in API Speci-fication 6A equipment to screen materials with poor notch toughness.This should help tominimize brittle fracture of wellhead and of christmas tree equipment in the field.A minimum average of 15 ft-lb is justified in API Specification 6A for all temperatureclassifications of all PSL levels of equipment.This does not preclude the use of the currentlateral expansion requirements for PSL level 4 equipment.The Task Group recommends20 ft-lb.This compromise required that the Task Group stipulate 15 ft-lb in the transversedirection:in order to satisfy logic that required 15 ft-lb in the transverse direction,a lon-gitudinal equivalentwas necessary.Additional work is required to establish brittle fracture criterion for API Specification6A materials using Charpy-fracture mechanics correlations.