Recommended Practice for Materials and Fabrication of 11/4CR-1/2Mo Steel Pressure Vessels for Service

Above 825 °F (440 °C)

API RECOMMENDED PRACTICE 934-E FIRST EDITION, AUGUST 2010

Recommended Practice for Materials and Fabrication of 11/4CR-1/2Mo Steel Pressure Vessels for Service

Above 825 °F (440 °C)

Downstream Segment

API RECOMMENDED PRACTICE 934-E FIRST EDITION, AUGUST 2010

Special Notes

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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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Classified areas may vary depending on the location, conditions, equipment, and substances involved in any given situation. Users of this RP should consult with the appropriate authorities having jurisdiction.

Users of this RP 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.

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Copyright © 2010 American Petroleum Institute

Foreword

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Should: As used in a standard, “should” denotes a recommendation or that which is advised but not required in order to conform to the specification.

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Suggested revisions are invited and should be submitted to the Standards Department, API, 1220 L Street, NW, Washington, DC 20005, standards@api.org.

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Contents

Page

1. Scope 1

2. Normative References 1

3. Terms, Definitions, and Acronyms 3

   1. Terms and Definitions 3

   2. Acronyms 4

4. Design 4

5. Base Metal Requirements 5

   1. Material Specification 5

   2. Steel Making Practice 5

   3. Chemical Composition Limits 5

   4. Heat Treatment 6

   5. Mechanical Properties 6

6. Welding Consumable Requirements 7

   1. Material Requirements 7

   2. Mechanical Requirements 7

7. Welding, Heat Treatment and Production Testing 7

   1. General Welding Requirements 7

   2. Welding Procedure Qualification 8

   3. Preheat and Dehydrogenation Heat Treatment 8

   4. Production Testing of Base Metal Welds 9

   5. Weld Overlay or Integral Clad 10

   6. Final PWHT 11

8. Nondestructive Examination (NDE) 12

   1. General 12

   2. NDE Prior to Fabrication 12

   3. NDE During Fabrication 12

   4. NDE After Fabrication and Prior to Final PWHT 12

   5. NDE After Final PWHT 13

   6. Positive Material Identification 13

9. Hydrostatic Testing 13

10. Preparations for Shipping 13

11. Documentation 14

Figure

1 Location of Vickers Hardness Indentations 9

Table

1 Base Metal Specifications 5

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Introduction

This recommended practice (RP) applies to new pressure vessels in petroleum refining, petrochemical and chemical facilities in which fluids are processed at temperatures in the 825 °F to 1100 °F (440 °C to 595 °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 RP with additional proprietary requirements.

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Recommended Practice for Materials and Fabrication of 11/4CR-1/2Mo Steel Pressure Vessels for Service Above 825 °F (440 °C)

1. Scope

   This recommended practice (RP) includes materials and fabrication requirements for new 11/4Cr-1/2Mo steel and 1Cr- 1/2Mo pressure vessels and heat exchangers for high temperature service. It applies to vessels that are designed, fabricated, certified, and documented in accordance with ASME Code Section VIII, Division 1.

   
   

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

   
   

   The interior surfaces of these pressure vessels may have an austenitic stainless steel, ferritic stainless steel, or nickel alloy weld overlay or cladding to provide additional corrosion resistance.

   
   

   This RP is applicable to wall (shell) thicknesses from 1 in. (25 mm) to 4 in. (100 mm). Integrally reinforced nozzles, flanges, tubesheets, bolted channel covers, etc. can be greater than 4 in. (100 mm). At shell or head thicknesses greater than 4 in. (100 mm), 11/4Cr-1/2Mo and 1Cr-1/2Mo have been shown to have difficulty meeting the toughness requirements given in this document, but this does not preclude the use of this alloy if these properties can be met or if the equipment is designed with stresses below the threshold for brittle fracture. Although outside of the scope, this document can be used as a resource for vessels down to 0.5 in. (12.7 mm) shell thickness with changes defined by the purchaser.

   
   

   This RP is not intended for use for equipment operating below 825 °F (440 °C). Refer to API 934-C for information on design for equipment operating at lower temperature ranges. Since hydrotreaters typically are designed to temperatures lower than 825 °F (440 °C), the guidelines in this RP do not apply to most hydrotreaters. Also, since coke drums typically fail due to fatigue and not due to reheat cracking; these RPs may not be appropriate for all aspects of coke drums.

   
   

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 Recommended Practice 582, Welding Guidelines for the Chemical, Oil, and Gas Industries

API Recommended Practice 934-A, Materials and Fabrication of 21/4Cr-1Mo, 21/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr- 1Mo-1/4V Steel Heavy Wall Pressure Vessels for High Temperature, High Pressure Hydrogen Service

API Recommended Practice 934-C, Materials and Fabrication of 11/4Cr-1/2Mo Steel Heavy Wall Pressure Vessels for High Pressure Hydrogen Service Operating at or Below 825 °F (440 °C)

API Recommended Practice 934-D, Technical Report on the Materials and Fabrication Issues of 11/4Cr-1/2Mo and 1Cr-1/2Mo Steel Pressure Vessels

API Publication 938-A, An Experimental Study of Causes and Repair of Cracking of 11/4Cr-1/2Mo Steel Equipment

ASME Boiler and Pressure Vessel Code 1, Section II—Materials; Part A—Ferrous Material Specifications; Part C,

Specification for Welding Rods, Electrodes and Filler Metals; Part D—Properties

1 ASME International, 3 Park Avenue, New York, New York 10016-5990, www.asme.org.

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