Aços liga e inoxidavel

Aços liga e inoxidavel

(Parte 1 de 14)

Stainless Steels and Specialty Alloys

for Modern Pulp and Paper Mills

Reference Book Series No 1 025

The material presented in this publication has been prepared for the general information of the reader and should not be used or relied on for specific applications without first securing competent advice.

The Nickel Development Institute,its members,staff and consultants do not represent or warrant its suitability for any general or specific use and assume no liability or responsibility of any kind in connection with the information herein.

Prepared by a Task Force of the Metals Subcommittee of the Corrosion and Materials Engineering Committee of the Technical Association of the Pulp and Paper Industry and the Nickel Development Institute

Senior Editor: Arthur H.Tuthill P.E.

The Nickel Development Institute is an international nonprofit organization serving the needs of people interested in the application of nickel and nickel-containing materials.

Printed on recycled paper in Canada

North America Nickel Development Institute 214 King Street West - Suite 510 Toronto, Ontario Canada M5H 3S6 Telephone1 416 591 7999 Fax1 416 591 7987 E-mail nidi_toronto@nidi.org

Europe Nickel Development Institute 42 Weymouth Street London, England W1G 6NP Telephone44 20 7493 7999 Fax44 20 7487 4964 E-mail nidi_london_uk@nidi.org

Nickel Development Institute European Technical Information Centre The Holloway, Alvechurch Birmingham, England B48 7QB Telephone44 1527 584777 Fax44 1527 585562 E-mail nidi_birmingham_uk@nidi.org

Japan Nickel Development Institute 1-3, 5-chome, Shimbashi Minato-ku, Tokyo, Japan Telephone81 3 3436 7953 Fax81 3 3436 2132 E-mail nidi_japan@nidi.org

Central & South America Nickel Development Institute c/o Instituto de Metais Não Ferrosos Rua Coronel Paulino Carlos, 194 04006-040 São Paulo-SP, Brazil Telephone55 1 3887 2033 Fax55 1 3885 8124

India Nickel Development Institute K-36, 1st Floor Hauz Khas Enclave (behind Hauz Khas Post Office) New Delhi 110 016 India Telephone91 1 686 5631 Fax91 1 686 3376 E-mail nidi_india@nidi.org

Australasia Nickel Development Institute 150 Drummond Street, Suite 3 Carlton, Victoria 3053 Australia Telephone61 3 9650 9547 Fax61 3 9650 9548 E-mail nidi_australia@nidi.org

South Korea Nickel Development Institute Olympia Building, Room 811 196-7 Jamsilbon-Dong, Songpa-Ku Seoul 138 229, South Korea Telephone82 2 419 6465 Fax82 2 419 2088 E-mail nidi_korea@nidi.org

China Nickel Development Institute Room 677, Poly Plaza Office Building 14 Dongzhimen Nandajie Beijing, China 100027 Telephone86 10 6500 18 (ext. 3677)

Fax86 10 6501 0261 E-mail nidi_china@nidi.org w.nidi.org

Members of NiDI BHP Billiton Codemin S.A. Falconbridge Limited Inco Limited Inco TNC Ltd. Nippon Yakin Kogyo Co., Ltd. OM Group, Inc. P.T.International Nickel Indonesia Sherritt International Corporation Sumitomo Metal Mining Co., Ltd. WMC Limited

Aug 02/5.0

1.1The Present4
1.2Life Cycle Costs6
1.3The Future7
REFERENCES9

1. INTRODUCTION

Corrosion Resistant Alloys10

2.TABLES OF COMPOSITION AND PROPERTIES OF COMMON ALLOYS 2.1Typical Composition of Wrought

2.2Mechanical Properties and Pitting Resistance

Corrosion Resistant Alloys1

Equivalent Number (PREN) of Wrought

ASTM Specifications and Producers12

2.36% and 7% Mo Austentic Stainless Steels –

(PREN) of Cast Alloys13

2.4Typical Composition,Mechanical Properties and Pitting Resistance Equivalent Number

3.CHARACTERISTICS OF STAINLESS STEELS AND OTHER CORROSION RESISTANT COMMON ALLOYS 3.1Designations,Properties and Specifications. 14

3.2Austenitic Stainless Steels15
3.3Ferritic Stainless Steels18
3.4Martensitic Stainless Steels18
3.5Age Hardening Stainless Steels19
3.6Duplex Stainless Steels19
3.7Nickel Base Alloys19
3.8Other Alloys20
4.1Batch Digesters21
4.2Continuous Digesters27
4.3Ancillary Equipment32
REFERENCES35
5.BROWN STOCK WASHING39
REFERENCES40

4. DIGESTERS

6.1Black Liquor41
6.2Recovery Boiler47
6.3Chemical Recovery Tanks50
6.4Lime Kiln54
SUGGESTEDREADING56
7.TALL OIL57
REFERENCES61
8.AIR QUALITY CONTROL62
REFERENCES6

6.CHEMICAL RECOVERY

9.1The Environment67
9.2Construction Materials68
9.3Sulphur Dioxide Production69
9.4Digesters69

9.SULPHITE PROCESS Stainless Steels and Specialty Alloys for Pulp and Paper1

9.5Washing and Screening69
9.6Chemical Recovery71
9.7Chloride Control71
REFERENCES72
REFERENCES74
1.HIGH YIELD MECHANICAL PULPING75
REFERENCES7
12.WASTE PAPER RECYCLING78
13.1Stages of Bleaching80
13.2Non-Chlorine Bleaching Stages83
13.3Process Water Reuse84

13. BLEACHPLANT

Bleaching Equipment86
13.5Oxygen Bleaching8

13.4Selection of Materials for

and the Growing Use of Duplex89
REFERENCES91
14.STOCK PREPARATION92

13.6Pumps,Valves

15.1Introduction98
15.2The Wet End9
15.3The Dry End103
15.4White Water Corrosion and Cleaning107
REFERENCES1

15.PAPER MACHINE

16.1Alloys Old and New112
16.2Corrosion114
16.3Operating Stresses114
16.4Manufacturing Quality115
16.5Material Selection115
16.6In-Service Inspection115
REFERENCES116
17.FASTENERS117
REFERENCE119

16. SUCTIONROLLS

18.1Preparation for Welding120
18.2Welding Processes121
18.3Stainless Steel Weld Filler Metals122
18.4Pipe and Tube Welding125
18.5Dissimilar Metal Welding (DMW)126
18.6Post-Fabrication Cleaning127
REFERENCES130

18. WELDING Stainless Steels and Specialty Alloys for Pulp and Paper2

19.1General Considerations131
19.2Materials Selection131
REFERENCES133

19. ABRASION

20.1Alloy Usage – Materials of Reference134
20.2Intergranular Attack (IGA)135
20.3Passivation135
20.4Post Fabrication Cleaning136
20.5Crevice Corrosion,Pitting and PREN137
20.6Corrosion Data139
20.7Stress Corrosion Cracking139
20.8Inhibited HClCleaning140

20. CORROSION

Corrosion (MIC)141
20.10Corrosion Testing141
20.11Cast Alloys141
REFERENCES143
21.ABBREVIATIONS144

20.9Microbiologically Influenced Stainless Steels and Specialty Alloys for Pulp and Paper3

1.INTRODUCTIONby Arthur H.Tuthill,Nickel Development Institute

THE PRESENT by Arthur H.Tuthill,Nickel Development Institute

This bulletin is a major expansion and a complete rewrite and update of the American Iron and Steel Institute (AISI) 1982 bulletin,“Stainless Steels for Pulp and Paper”.It has been prepared to provide mill engineers with a good overview of the wrought and cast alloys currently used in sulphate and sulphite mills.The bulletin is application oriented.Alloys useful in the principal equipment found in 12 different sections of paper mills are supplemented by sections on alloy characteristics,fasteners,abrasion, welding and corrosion.Since the AISI Committee of Stainless Steel Producers,which sponsored the 1982 bulletin,no longer exists,this updated edition has been prepared by a Task Force of the Metals Subcommittee of the Corrosion and Materials Engineering Committee of the Technical Association of the Pulp and Paper Industry (TAPPI).The 1982 edition covered only wrought stainless steels.This edition includes both wrought and cast stainless steels and other alloys commonly used in this industry.New sections on tall oil,air quality control,mechanical pulping,waste paper,suction rolls,fasteners and abrasion have been added.The bulletin is designed to be a useful reference for mill engineers concerned with materials of construction for the equipment in everyday use.Figure 1-1is a generalized flow diagram of the principal processes in pulp and paper making.

Pulp and paper mills use stainless steel to avoid iron contamination of the product paper and to resist process corrosion.Although most mills use nominally the same sulphate kraft or sulphite process,there are sufficient mill-to-mill differences that can affect corrosion behaviour.This bulletin identifies alloys that are known to perform well in the individual applications cited,but mill engineers should be aware that conditions in their mill may differ sufficiently for performance to be somewhat different.Experience in each mill is the best guideline.

Each section of the original bulletin and the new sections have been prepared by a knowledgeable industry materials specialist,incorporating the many changes in the environment,mill processes and alloy usage that have occurred since 1982.Principal factors that have affected alloy usage and performance include the recycling of wash water streams,discontinuation of chlorine bleaching,expanded use of oxygen and hydrogen peroxide bleaching,increased corrosivity in chemical recovery and brown stock washing,as well as the increased sand and grit loading in pumps.

Discontinuation of chlorine stage bleaching has come to be known as elemental chlorine-free bleaching (ECF).Totally chlorine-free bleaching

Stainless Steels and Specialty Alloys for Pulp and Paper4

1.INTRODUCTION

Chip ConveyerWaste Paper

Pulper

(Parte 1 de 14)

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