Recommended Practice for Materials and Fabrication of 1¼Cr-½Mo Steel Pressure Vessels for Service above 825 ˚F (440 ˚C)

API RECOMMENDED PRACTICE 934-E SECOND EDITION, JANUARY 2018

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Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given situation. 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 contained herein.

Information concerning safety and health risks and proper precautions with respect to particular materials and conditions should be obtained from the employer, the manufacturer or supplier of that material, or the material safety data sheet.

API is not undertaking to meet the duties of employers, manufacturers, or suppliers to warn and properly train and equip their employees, and others exposed, concerning health and safety risks and precautions, nor undertaking their obligations 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 equipment and premises in determining the appropriateness of applying the Recommended Practice. At all times users should employ sound business, scientific, engineering, and judgment safety when using this Recommended Practice.

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Copyright © 2018 American Petroleum Institute

Foreword

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iii

Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, and Acronyms 3

   1. Terms and Definitions 3

   2. Acronyms 5

4. Design of Pressure Vessels and Heat Exchangers 5

   1. Design and Manufacture 5

   2. Coverage of Design Issues 6

5. Base Metal Requirements 6

   1. Material Specification 6

   2. Steelmaking Practice 7

   3. Chemical Composition Limits 7

   4. Heat Treatment 7

   5. Mechanical Properties 8

6. Welding Consumable Requirements 9

   1. Material Requirements 9

   2. Mechanical Requirements 9

7. Welding, Heat Treatment, and Production Testing 9

   1. General Welding Requirements 9

   2. Welding Procedure Qualification 10

   3. Preheat and Dehydrogenation Heat Treatment 11

   4. Production Testing of Base Metal Welds 11

   5. Weld Overlay or Integral Clad 12

   6. Final PWHT 13

8. Nondestructive Examination (NDE) 14

   1. General 14

   2. NDE Prior to Fabrication 14

   3. NDE During Fabrication 15

   4. NDE After Fabrication and Prior to Final PWHT 15

   5. NDE After Final PWHT 15

   6. Positive Material Identification 15

9. Hydrostatic Testing 15

10. Preparation for Shipping 16

11. Documentation 16

Bibliography 17

Figures

1 Location of Vickers Hardness Indentations 11

Tables

1 Base Metal ASME Specifications 6

v

Introduction

This recommended practice applies to new pressure vessels in petroleum refining, petrochemical, industrial gas, and chemical facilities in which fluids are processed at temperatures in the 825 °F to 1150 °F (440 °C to 620 °C) range. It is based on decades of industry operating experience and the results of recent experimentation and testing conducted by independent manufacturers, fabricators, and users of pressure vessels for this service.

Licensors and owners of process units in which these pressure vessels are to be used may modify and/or supplement this recommended practice with additional proprietary requirements.

vii

Recommended Practice for Materials and Fabrication of 1¼Cr-½Mo Steel Pressure Vessels for Service above 825 ˚F (440 ˚C)

1. Scope

   
   

   This recommended practice (RP) includes materials and fabrication requirements for new 1¼Cr-½Mo and 1Cr-½Mo steel pressure vessels, including heat exchanger shells and channels for elevated temperature service. It applies to vessels that are designed, fabricated, and documented in accordance with ASME Code Section VIII, Division 1 or Division 2 (hereafter referred to as “Code”).

   
   

   This document may also be used as a resource when planning to modify existing pressure vessels.

   
   

   The interior surfaces of these pressure vessels and heat exchangers (i.e. the surfaces exposed to the process) may or may not have an austenitic stainless steel (SS), ferritic SS, or nickel alloy weld overlay or cladding to provide additional corrosion resistance.

   
   

   Some 1¼Cr-½Mo and 1Cr-½Mo components with thicknesses greater than 4 in. (100 mm) have been shown to have difficulty meeting the Code toughness requirements. This recommended practice is primarily intended for wall thicknesses less than 4 in. (100 mm); a preferred option for thicker components is to use 2¼Cr-1Mo alloys.

   
   

   This RP is applicable to shell thicknesses greater than 1 in. (25 mm). Although outside of the scope, this document can be used as a resource for vessels down to lower shell thicknesses with changes defined by the purchaser.

   
   

   This RP is intended for use for 1¼Cr-½Mo and 1Cr-½Mo equipment operating between 825 °F (440 °C) and 1150 °F (620 °C). The primary in-service materials degradation mechanism addressed by the requirements herein is low creep ductility (LCD) cracking, which can occur at these operating temperatures if not properly addressed. LCD cracking is a form of reheat cracking.

   
   

   In many cases, 1¼Cr-½Mo and 1Cr-½Mo steel equipment being designed for temperatures >825 °F (>440 °C) operate with stresses below the threshold for brittle fracture [i.e. below 8 ksi (55 MPa) as reported in API 579-1/ASME FFS-11, or below 10% of ultimate tensile strength as reported in literature].

   
   

   Typical equipment covered by the scope of this RP includes catalytic reforming reactors and fluidized catalytic cracking (FCC) unit hot wall reactors. For information on 1¼Cr-½Mo and 1Cr-½Mo equipment operating at lower temperature ranges, refer to API RP 934-C. Since hydroprocessing units are typically operated at temperatures lower than 825 °F (440 °C), the guidelines in this RP (934-E) do not apply to most hydroprocessing units; instead, they are covered by RP 934-A or 934-C. Also, since coke drums typically are more susceptible to fatigue than LCD cracking, this RP excludes coke drums from the scope; they are addressed in API Technical Report 934-G.

   
   

2. Normative References

The following referenced documents are indispensable for 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 C-Specification for Welding Rods, Electrodes, and Filler Metals

1 ASME International, 3 Park Avenue, New York, New York 10016, www.asme.org.

2 API RECOMMENDED PRACTICE 934-E

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, Brazing, and Fusing Qualifications

ASME SA-20/SA-20M, Standard Specification for General Requirements for Steel Plates for Pressure Vessels

ASME SA-182/SA-182M, Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service

ASME SA-263, Standard Specification for Stainless Chromium Steel-Clad Plate

ASME SA-264, Standard Specification for Stainless Chromium-Nickel Steel-Clad Plate

ASME SA-265, Standard Specification for Nickel and Nickel-Base Alloy-Clad Steel Plate

ASME SA-335/SA-335M, Standard Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service

ASME SA-336/SA-336M, Standard Specification for Alloy Steel Forgings for Pressure and High-Temperature Parts

ASME SA-369/SA-369M, Standard Specification for Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service

ASME SA-387/SA-387M, Standard Specification for Pressure Vessel Plates, Alloy Steel, Chromium-Molybdenum

ASME SA-530/SA-530M, Standard Specification for General Requirements for Specialized Carbon and Alloy Steel Pipe

ASME SA-578/SA-578M, Standard Specification for Straight-Beam Ultrasonic Examination of Rolled Steel Plates for Special Applications

ASNT2 Recommended Practice No. SNT-TC-1A, Personnel Qualification and Certification in Nondestructive Testing

ASNT CP-189, Standard for Qualification and Certification of Nondestructive Testing Personnel

ASTM3 G146, Standard Practice for Evaluation of Disbonding of Bimetallic Stainless Alloy/Steel Plate for Use in High-Pressure, High-Temperature Refinery Hydrogen Service

AWS4 A4.2M (ISO 8249:2000 MOD), Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal

AWS A4.3, Standard Methods for Determination of the Diffusible Hydrogen Content of Martensitic, Bainitic, and Ferritic Steel Weld Metal Produced by Arc Welding

2 American Society for Nondestructive Testing, 1711 Arlingate Lane, Columbus, Ohio 43228-0518, www.asnt.org.

3 ASTM International, 100 Barr Harbor Drive, West Conshohocken, Pennsylvania 19428, www.astm.org.

4 American Welding Society, 550 NW LeJeune Road, Miami, Florida 33126, www.aws.org.