M00044378
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API RP 934-A Materials and Fabrication of 2-1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High-temperature, High Pressure Hydrogen Service
standard by American Petroleum Institute, 05/01/2008
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API RECOMMENDED PRACTICE 934-A SECOND EDITION, MAY 2008
ADDENDUM 1, FEBRUARY 2010
ADDENDUM 2, MARCH 2012
Downstream Segment
API RECOMMENDED PRACTICE 934-A SECOND EDITION, MAY 2008
ADDENDUM 1, FEBRUARY 2010
ADDENDUM 2, MARCH 2012
Special Notes
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Neither API nor any of API's employees, subcontractors, consultants, committees, or other assignees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publication. Neither API nor any of API's 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 the accuracy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any authorities having jurisdiction with which this publication may conflict.
API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices.
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Copyright © 2008 American Petroleum Institute
Foreword
Nothing contained in any API publication is to be construed as granting any right, by implication or otherwise, for the manufacture, sale, or use of any method, apparatus, or product covered by letters patent. Neither should anything contained in the publication be construed as insuring anyone against liability for infringement of letters patent.
This document was produced under API standardization procedures that ensure appropriate notification and participation in the developmental process and is designated as an API standard. Questions concerning the interpretation of the content of this publication or comments and questions concerning the procedures under which this publication was developed should be directed in writing to the Director of Standards, American Petroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to reproduce or translate all or any part of the material published herein should also be addressed to the director.
Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least every five years. A one-time extension of up to two years may be added to this review cycle. Status of the publication can be ascertained from the API Standards Department, telephone (202) 682-8000. A catalog of API publications and materials is published annually and updated quarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.
Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, D.C. 20005, standards@api.org.
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Contents
Page
Scope 1
References 1
Terms, Definitions, and Acronyms 2
Terms and Definitions 2
Acronyms 4
Design 4
Base Metal Requirements 5
Material Specifications 5
Steel Making Practice 6
Chemical Composition Limits 6
Heat Treatment 6
Mechanical Properties 6
Welding Consumable Requirements 8
Material Requirements 8
Mechanical Properties 8
Welding, Heat Treatment and Production Testing 9
General Welding Requirements 9
Welding Procedure Qualification 10
Preheat and Heat Treatments During Base Metal Welding 11
Production Testing of Base Metal Welds 12
Weld Overlay 13
Final Postweld Heat Treatment (PWHT) 15
Nondestructive Examinations (NDE) 16
General 16
NDE Prior to Fabrication 16
NDE During Fabrication 16
NDE After Fabrication and Prior to Final PWHT 17
NDE After Final PWHT 17
Positive Material Identification 17
Hydrostatic Testing 17
Preparations for Shipping 18
Documentation 18
Annex A (informative) Guidance for Inspection for Transverse Reheat Cracking 19
Annex B (informative) Weld Metal/Flux Screening Test for Reheat Cracking Susceptibility 30
Bibliography 43
Figures
1 Location of Vickers Hardness Indentations 11
Schematic Showing of Reheat Cracking Locations 25
B-scan for Detecting Transverse Defects with TOFD 26
Alternate Probe Setup with Offset for Detecting Transverse Defects 27
TOFD Sensitivity Demonstration Block 28
Characterization of Reheat Cracks Using Pulse-echo UT 29
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Contents
Page
Example of a Gripping Device Devoted to Threaded-end Specimens 33
Geometry of the Weld Joint to be Used for the Screening Test Coupon 36
Welding Sequence to be Used for the Screening Test 36
Example of Strongbacks Used to Minimize Coupon Distortion. 36
Position of Pre-forms Inside the Welded Zone—Macrographic View 37
Position of Pre-forms Inside the Welded Zone—Schematic View 37
Detailed Geometry of RHC Standard Specimen. 38
Location of the Thermocouples on the RHC Standard Specimen 39
Illustration of Heating Requirements on Test Specimens 40
Tables
Base Metal Specifications 5
Heat Treatment of Test Specimens 7
Maximum Operation Conditions Correlated to Testing Conditions at 450 °C (842 °F) 14
Test Conditions Domains 14
PWHT Holding Temperature and Time 16
TOFD Guideline for Identifying Transverse Reheat Cracks 23
Manual Pulse-echo Shear Wave Guideline for Identifying Transverse Reheat Cracks 24
Welding Parameters to be Used for Welding of Screening Test Coupons 35
Sample Test Certificate 42
Introduction
This recommended practice applies to new heavy wall pressure vessels in petroleum refining, petrochemical, and chemical facilities in which hydrogen or hydrogen-containing fluids are processed at elevated temperature and pressure. It is based on decades of industry operating experience and the results of experimentation and testing conducted by independent manufacturers and purchasers of heavy wall pressure vessels for this service.
Licensors and owners of process units in which these heavy wall pressure vessels are to be used may modify and/or supplement this recommended practice with additional proprietary requirements.
Materials and Fabrication of 2 1/4Cr-1Mo, 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High-temperature, High-pressure Hydrogen Service
Scope
This recommended practice presents materials and fabrication requirements for new 2 1/4Cr and 3Cr steel heavy wall pressure vessels for high-temperature, high-pressure hydrogen service. It applies to vessels that are designed, fabricated, certified, and documented in accordance with ASME BPVC, Section VIII, Division 2, including Section 3.4, Supplemental Requirements for Cr-Mo Steels and ASME Code Case 2151, as applicable. This document may also be used as a resource when planning to modify an existing heavy wall pressure vessel.
A newer ASME BPVC, Section VIII, Division 3, is available and has higher design allowables, however it has much stricter design rules (e.g. fatigue and fracture mechanics analyses required) and material testing requirements. It is outside the scope of this document.
Materials covered by this recommended practice are conventional steels including standard 2-1/4Cr-1Mo and 3Cr-1Mo steels, and advanced steels which include 2 1/4Cr-1Mo-1/4V, 3Cr-1Mo-1/4V-Ti-B, and 3Cr-1Mo-1/4V-Nb-Ca steels. This document may be used as a reference document for the fabrication of vessels made of enhanced steels (steels with mechanical properties increased by special heat treatments) at purchaser discretion. However, no attempt has been made to cover specific requirements for the enhanced steels.
The interior surfaces of these heavy wall pressure vessels may have an austenitic stainless steel weld overlay lining to provide additional corrosion resistance. A stainless clad lining using a roll-bonded or explosion-bonded layer on Cr- Mo base metal may be acceptable, but is outside the scope of this document.
References
The following referenced documents are cited in the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
API RP 582, Welding Guidelines for the Chemical, Oil, and Gas Industries
ASME1 Boiler and Pressure Vessel Code, Section II—Materials; Part A—Ferrous Material Specifications; Part C—
Specifications for Welding Rods, Electrodes and Filler Metals; Part D—Properties ASME Boiler and Pressure Vessel Code, Section V—Nondestructive Examination
ASME Boiler and Pressure Vessel Code, Section VIII—Rules for Construction of Pressure Vessels, Division 1
ASME Boiler and Pressure Vessel Code, Section VIII—Rules for Construction of Pressure Vessels, Division 2—Alternative Rules
ASME Boiler and Pressure Vessel Code, Section IX—Welding and Brazing Qualifications
ASME Code Case 2151-1, 3 Chromium-1 Molybdenum-1/4 Vanadium-Columbium-Calcium Alloy Steel Plates and Forgings
ASME SA-20, Standard Specification for General Requirements for Steel Plates for Pressure Vessels
1ASME International, 3 Park Avenue, New York, New York 10016, www.asme.org.
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