Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures

API RECOMMENDED PRACTICE 2Z FOURTH EDITION, SEPTEMBER 2005

REAFFIRMED, SEPTEMBER 2020

Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures

Upstream Segment

API RECOMMENDED PRACTICE 2Z FOURTH EDITION, SEPTEMBER 2005

REAFFIRMED, SEPTEMBER 2020

SPECIAL NOTES

API 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 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, con- sultants, or other assignees represent that use of this publication would not infringe upon pri- vately 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 publi- cation may conflict.

API publications are published to facilitate the broad availability of proven, sound engineer- ing 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.

Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such prod- ucts do in fact conform to the applicable API standard.

All rights reserved. No part of this work may be reproduced, 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, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001.

Copyright © 2005 American Petroleum Institute

FOREWORD

This Recommended Practice is under jurisdiction of the API Subcommittee on Standardiza- tion of Offshore Structures.

The purpose of this recommended practice is to provide recommendations for the pre-pro- duction qualification of steelmaking procedures for steel plates for use in welded offshore structures.

This standard shall become effective on the date printed on the cover but may be used volun- tarily from the date of distribution.

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 federal, state, or municipal regulation with which this publication may conflict.

Suggested revisions are invited and should be submitted to the director of the Exploration and Production Department, American Petroleum Institute, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001.

Nothing contained in any API publication is to be construed as granting any right, by impli- cation 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 stan- dard. 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,

200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001. 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, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001.

Suggested revisions are invited and should be submitted to the Standards and Publications Department, API, 200 Massachusetts Avenue, NW, Suite 1100, Washington, DC 20001, standards@api.org.

iii

CONTENTS

Page

1. INTRODUCTION 1

   1. Purpose 1

   2. Scope 1

   3. General Requirements 1

2. REFERENCES 2

3. QUALIFICATION FOR HAZ TOUGHNESS 2

4. DELAYED CRACKING TEST 13

   1. Purpose 13

   2. Controlled Thermal Severity (CTS) Test 13

   3. The Y-Groove Test 13

   4. Requirements 13

   5. Commentary 14

5. RE-QUALIFICATION 14

APPENDIX A SUGGESTIONS FOR ORDERING API RP 2Z PRE-PRODUCTION QUALIFICATION 19

Figures

1. Single-bevel and K-bevel Weld Preparations 3

2. Various Regions of a Single-pass, Bead-on-plate Weld 7

3a Eliminated, Altered and Unaltered Regoins of a Two-phase, Bead-on-plate Weld .8 3b Identification of Some Altered and Unaltered Regions 8

4a HAZ Regions in a Multi-pass Weld with One Plate Edge, Unbeveled 9

4b Unaltered Coarse-grain HAZ (CGHAZ) in a Multi-pass Weld

with one Plate Edge, Unbeveled 10

4c Inter critically and Sub Critically Reheated CGHAZ Regions

(IRCG and SRCG, Respectively 11

4d Unaltered Subcritical HAZ (SCHAZ) 12

5a Sectioning the Weld Half of a HAZ CTOD Specimen 16

5b Calculation of CG Region Sampled by the Fatigue Crack Tip 17

6 Sectioning Both Halves of a HAZ CTOD Specimen to

Calculate CG Region Percentage 18

Tables

1. CTOD Testing Requirements 4

2. Tolerances for Minor and Major Changes in Melting, Casting,

and Processing Variables Other Than Chemistry 15

v

Recommended Practice for Preproduction Qualification for Steel Plates for Offshore Structures

1. Introduction

   1. PURPOSE

      The purpose of these recommendations is to provide the purchaser with information which can be used to minimize the amount of time and testing necessary to prepare and certify fabrication welding procedures (and to assure that the steel to be supplied is inherently suitable for welding) with particular attention to fracture toughness and resistance to cracking of the heat affected zone. It is presupposed that welding procedures suitable for the demonstrated capabilities of the steel and intended service will be sepa- rately developed.

      1. The specific testing required shall be that described in either Section 3 or 4 or both, as specified in the purchase order.

      2. Demonstration of conformance to the recommendations of this practice qualifies a particular mill to produce steel manu- factured to the specific chemical composition range, melting practice, and processing practice for which conformance was estab- lished. The qualification is applicable to all orders for material produced under the conditions qualified.

      3. A significant change in chemical composition or processing practice that could be detrimental to either weldability or toughness shall require either a separate full qualification (for major change) or an abbreviated re-qualification (for minor change), as described in Section 5.

      4. Prior qualification may be accepted for the fulfillment of the recommendations of this practice. Testing to a wider range of heat input, higher CTOD values, or lower test temperatures is encouraged, and shall be deemed to satisfy the minim recom- mendations of this Practice.

1. SCOPE

   This Recommended Practice covers requirements for Preproduction qualification, by special welding and mechanical testing, of specific steelmaking and processing procedures for the manufacture of steel of a specified chemical composition range by a spe- cific steel producer. This is a Recommended Practice for material selection and qualification, but not for the performance of pro- duction weld joints. This Recommended Practice was developed in conjunction with, and is intended primarily for use with, API Specifications 2W and 2Y. However, it may be sued as a supplement to other material specification s (e.g., API Specification 2H) if so desired.

   
   

2. GENERAL REQUIREMENTS

   1. Unless otherwise specified, the testing recommended by this practice need only include material from a single heat of steel produced to the specific range of chemical composition to be qualified.

   2. The plate processing, welding, and testing shall be conducted by or under the control of the steel producer, but shall be witnessed by a third party or a representative of a purchaser.

   3. The test results, together with a detailed description of the processing of the steel, shall be documented by the producer and a copy provided to the purchaser. It is not intended, however, that proprietary information be included in the documentation. It is intended that the steel producer's "know-how" shall remain confidential. It is necessary, however, that sufficient information be included in the documentation package so that a purchaser can confirm at a later date that all essential procedures are being fol- lowed. At the very least, the manufacturer's process shall be designated by a code number or designation sufficient to provide traceability of process variables.

   4. The chemical composition of the steel, as determined by heat analysis, shall conform to the requirements of the applicable industry standard under which it is to be produced. Within these typically broad limits, the steelmaker shall nominate the aim chemical composition and working range which define limiting essential variables for which the Preproduction qualification may be assumed to remain valid.

Tests conducted on any one heat shall qualify subsequent production heats described in Section 5.

1