_RP_939-C-2019.pdf

Guidelines for Avoiding Sulfidation(Sulfidic)Corrosion Failures in Oil RefineriesAPI RECOMMENDED PRACTICE 939-CSECOND EDITION,JANUARY 2019Special NotesAPI publications necessarily address problems of a general nature.With respect to particular circumstances,local,state,and federal laws and regulations should be reviewed.Neither API nor any of APIs employees,subcontractors,consultants,committees,or other assignees makes anywarranty or representation,either express or implied,with respect to the accuracy,completeness,or usefulness of theinformation contained herein,or assumes any liability or responsibility for any use,or the results of such use,of anyinformation or process disclosed in this publication.Neither API nor any of APIs employees,subcontractors,consultants,or other assignees represent that use of this publication would not infringe upon privately owned rights.API publications may be used by anyone desiring to do so.Every effort has been made by the Institute to assure theaccuracy and reliability of the data contained in them;however,the Institute makes no representation,warranty,orguarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss ordamage resulting from its use or for the violation of any authorities having jurisdiction with which this publication mayconflict.API publications are published to facilitate the broad availability of proven,sound engineering and operatingpractices.These publications are not intended to obviate the need for applying sound engineering judgmentregarding when and where these publications should be utilized.The formulation and publication of API publicationsis not intended in any way to inhibit anyone from using any other practices.Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standardis solely responsible for complying with all the applicable requirements of that standard.API does not represent,warrant,or guarantee that such products do in fact conform to the applicable API standard.Classified areas may vary depending on the location,conditions,equipment,and substances involved in any givensituation.Users of this Recommended Practice should consult with the appropriate authorities having jurisdiction.Users of this Recommended Practice should not rely exclusively on the information contained in this document.Sound business,scientific,engineering,and safety judgment should be used in employing the information containedherein.API is not undertaking to meet the duties of employers,manufacturers,or suppliers to warn and properly train andequip their employees,and others exposed,concerning health and safety risks and precautions,nor undertaking theirobligations to comply with authorities having jurisdiction.Where applicable,authorities having jurisdiction should be consulted.Work sites and equipment operations may differ.Users are solely responsible for assessing their specific equipmentand premises in determining the appropriateness of applying the Recommended Practice.At all times users shouldemploy sound business,scientific,engineering,and judgment safety when using this Recommended Practice.All rights reserved.No part of this work may be reproduced,translated,stored in a retrieval system,or transmitted by any means,electronic,mechanical,photocopying,recording,or otherwise,without prior written permission from the publisher.Contact the Publisher,API Publishing Services,1220 L Street,NW,Washington,DC 20005.Copyright 2019 American Petroleum InstituteForewordNothing contained in any API publication is to be construed as granting any right,by implication or otherwise,for themanufacture,sale,or use of any method,apparatus,or product covered by letters patent.Neither should anythingcontained in the publication be construed as insuring anyone against liability for infringement of letters patent.The verbal forms used to express the provisions in this document are as follows.Shall:As used in a standard,“shall”denotes a minimum requirement in order to conform to the standard.Should:As used in a standard,“should”denotes a recommendation or that which is advised but not required in orderto conform to the standard.May:As used in a standard,“may”denotes a course of action permissible within the limits of a standard.Can:As used in a standard,“can”denotes a statement of possibility or capability.This document was produced under API standardization procedures that ensure appropriate notification andparticipation in the developmental process and is designated as an API standard.Questions concerning theinterpretation of the content of this publication or comments and questions concerning the procedures under whichthis publication was developed should be directed in writing to the Director of Standards,American PetroleumInstitute,1220 L Street,NW,Washington,DC 20005.Requests for permission to reproduce or translate all or any partof the material published herein should also