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DESIGN AND FABRICATION OF AN IMPROVED CRACK GROWTH

TESTING APPARATUS WITH STRESS CORROSION CRACKING (SCC)

STUDY

IBRAHIM MANAI BIN ABDUL HAKIM

This project is submitted in partial fulfillment of the requirement for the Degree

of Bachelor (Honours) of Mechanical Engineering and Manufacturing System

Report submitted To

Faculty of Engineering

UNIVERSITI MALAYSIA SARAWAK (UNIMAS)

2006

111

Dedicate to my loving father and mother and all my friends who

was supported and encouraged me

Thank you for all the support and encouragement

iv

ACKNOWLEDGEMENTS

Alhamdulillah, Thank God for all His Blessing and permission I was able to

complete this Final Year Project. First and foremost, I would like to thank all my

supervisors Dr. Mohd Omar Bin Abdullah, En. Ghazali Bin Tambi and Pn. Mahshuri

Binti Yusof for their guidance, advices and patience in assisting me to complete this

report. I believe that without their support, I could not finish the project in time. My

special thank to my dad, Abdul Hakim Bin Zaini and my mom, Aminah Binti

Abdullah for their encouragement, financial support and loves. Apart of that, special

thanks to Terida Binti Morni for her moral support and loves that encouraged me to

finish this project.

In addition, thanks to all the lab technicians Mr. Masri, Mr. Sabariman, Mr

Zaidi, Mr Ireman, Mr Rhyier and Kak Miza for their helps in providing ideas,

support, guidance and assistance in this project. Without them, I believe that I could

not finish the project in time and unable to meet the objective of the project.

Thanks to all my friends, Bob, Pojan, Rafiq, Rasyid, Sepul and Talib, who

help me during the design process and fabrication process. It's always a pleasure to

have them as friends who help me with their point of view and generous critics.

V

ABSTRACT

A study of Stress Corrosion Cracking or SCC is a main part of this

project. Ammonia tank is related with the SCC problem especially at - 33 °C. Stress

Corrosion Cracking occurs relatively slow but due to certain solution will increase

the SCC effect. The prototype of the Crack Growth Testing Apparatus had been

redesign by Axiomatic Design approaches following the basic step of design. During

the redesigning process; design, material and component analysis done and

"Solidwork 2003" design software is used. Improvement is done to solve the

problems occur in existing apparatus. Methodology also used for development of the

project and to determine, examine the capabilities of the product. Few testing and

observations are done and data is analyzed for future research. The achievement,

limitation and future recommendation are identified so that the aim of the study can

be achieved.

vi

ABSTRAK

Kajian mengenai "Stress Corrosion Cracking" yang juga dikenali sebagai SCC

merupakan aspek utama dalam projek ini. Tangki ammonia dikaitkan dengan masalah

SCC terutamanya pada suhu - 33 °C. "Stress Corrosion Cracking" berlaku perlahan

tetapi kadarnya akan meningkatkan kadar SCC disebabkan oleh sesetengah cecair.

Model untuk "Crack Growth Testing Apparatus" telah direkabentuk semula melalui

penggunaan "Axiomatic Design" mengikut panduan langkah asas dalam

merekabentuk. Semasa proses merekabentuk semula; rekabentuk, bahan dan analisis

komponen dilakukan dan program "Solidwork 2003" digunakan. Pembaikansemula

dilakukan untuk menyelesaikan masalah yang ada. Metodologi juga digunakan

untuk membangunkan projek ini dan untuk mencari, memeriksa keupayaan produk

yang dihasilkan. Beberapa ujikaji dan pemerhatian dilakukan dan data dianalisa

untuk kajian masa hadapan. Kejayaan, kekurangan dan cadangan masa depan juga

dikenalpasti supaya matlamat sebenar projek ini tercapai.

vii

LIST OF CONTENT

Borang Pengesahan Tesis

Approval Sheet

Acknowledgment

Abstract

Abstrak

CHAPTER 1: INTRODUCTION

1 .0

Background

1.1 Ammonia Storage Tank

1.2 Aim and Objective

CHAPTER 2: LITERATURE REVIEW

2.0 Introduction

2.1 Stress Corrosion Cracking

2.1.2 Mechanism of Stress Corrosion Cracking

2.2 Stress Corrosion Cracking (SCC) in Hazardous Solution

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2.3 The Design Software 25

2.4 Design Approaches 25

2.4.1 Axiomatic Design 26

2.4.2 Triz or TIPS (Technical of Inventive Problem Solving) 29

2.4.3 Quality Function Deployment (QFD) 35

2.5 Summary 40

viii

CHAPTER 3: RESEARCH METHODOLOGY

3.0 Introduction

3.1 Methodology Approaches

3.2 Basic Step in Designing

3.2.1 Study on Relevant Subject

3.2.2 Design the Product

3.3 Design, Material and Component Analysis

3.3.1 Material Selection

3.3.2 Bearing Selection

3.3.3 Gasket Selection

3.3.4 Study on Types of Joint

3.4 Design Description

3.4.1 Specification

3.4.2 Problem of the Existing Product

3.4.3 Improvement and Solution Theoretically

3.5 Concept Generation

3.6 Decision Making

3.7 Improved Design

3.7.1 Specification

3.8 Identifying Method and Materials

3.8.1 Testing Equipment

3.8.2 Torque Wrench

3.8.3 Compact Tension Specimen Preparation

3.8.4 Fabrication of the Prototype and Commissioning

3.9 Testing the Prototype

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ix

3.10 Procedure for Strain Measurement in Relation

to Strain-Torque Characteristic Testing of the Prototype.

3.11 Observation and Data Collection

3.12 Data Analysis

3.13 Summary

CHAPTER 4: RESULT AND DISCUSSION

4.0 Introduction

4.1 Results

4.1.1 Discussion of the Concept

4.2 Testing the Prototype and Data Collection

4.2.1 Test 1: Observation Test

4.2.2 Test 2: Collecting Data with Strain Gauges

4.2.3 Test 3: Leakage Observation

4.3 Discussion

4.3.1 Discussion of the Test Result and Observation

4.4 Summary

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CHAPTER 5: CONCLUSION AND RECOMMENDATION FOR FUTURE

WORK

5.0 Introduction 98

5.1 Achievement from the Fabrication of the Crack Growth Apparatus 98

5.2 Limitation 99

5.3 Recommendation for Future Research/Work 100

5.4 Conclusion 103

X

REFERENCES

APPENDIX I (DETAIL PART DRAWING)

APPENDIX II (TESTING EQUIPMENT

104

I

XVII

Xl

LIST OF TABLES

Table Page

2.1 Characteristic of environmentally induced Cracking 13

2.2 SCC results of titanium in n-propanol solutions in the

presence of FeC13 + H2O 14

2.3 The 39 Engineering Parameters 33

2.4 The 40 Inventive Principles 34

3.1 Basic design considerations 42

3.2 General properties of steel 47

3.3 Type of Bearing 49

3.4 Specification of existing product 53

3.5 A new Crack Growth Testing Apparatus Part by Part

Features 68

3.6 Specification of a new Crack Growth Apparatus 73

4.1 Data collected from the testing 92

X11

LIST OF FIGURES

Figure Page

1.1 Design of 30000 tones of ammonia storage tank

1.2 Design of 10000 tones of ammonia storage tank

1.3 Ammonia storage tank design

2.1 Simultaneous Tensile Stress, susceptible

metallurgical condition and critical corrosive solution

required for stress corrosion cracking a

2.2 SCC expressed as propagation rate: corrosion rate vs.

FeCl3 concentration

2.3 Phase shift evolution during a SSRT test with

sensitised Type 304 SS in a 5N H2SO4 +0.1 M NaCl

solution

2.4 Photograph of the two samples after testing under

constant load on Type 304 SS in a boiling acidified

sodium chloride solution, the upper sample was free

of stress; the lower sample was subjected to a

constant load

2.5 Crack initiation and propagation is related to the

evolution in phase shifts during a SSRT test of

sensitised Type 304 SS in 0.01 M Na2SO4 at 300 °C

2.6 Intergranular stress corrosion cracking (IGSCC) of

sensitised Type 304 SS in 0.01 M Na2SO4 at 300 °C.

4

5

6

10

15

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xiii

2.7 Crack initiation and propagation is related to the

evolution in phase shift during a SSRT test of

solution annealed Type 304 SS in 0.01 M Na2SO4 at

300 °C

2.8 Transgranular stress corrosion cracking (TGSCC) of

the solution annealed specimen of Type 304 SS in

0.01 M Na2SO4 at 300 °C.

2.9 Load v time curves generated by SSRT tests of mild

steel in caustic (600 gpl, i. e. 15 N) and inert (paraffin

oil-PFO) environments at 100 °C (strain rate: 0.12 x

20

20

10 bs ý). 21

2.10 Low magnification SEM fractographs after slow

strain rate testing (strain rate: 0.12 x 10- 6 s- 1) of a

mild steel at 100 °C: (a) suggests SCC (much less

reduction-of-area (ROA)) when tested in 600 gpl (15

N) caustic solution, and (b) considerable ROA when

tested in caustic solution of much lower

concentration (i. e. 7.5 N).

2.11 Representative SEM fractographs comparing fracture

surfaces of the specimens tested at a strain rates (0.12

x 10-6and0.25x 10-ß's- 1) at 150°C in

(a) Synthetic Bayer liquor (part C failed by SCC, and

part B, mechanically), and (b) paraffin oil.

22

24

xiv

Nomenclature

6

dFs

F

Rf

Rb

Vs

E

n

k

Strain

Electrical resistance

Strain gauge factor

Tensile strain pulse increase

Ballistic resistor

Potential difference of strain gauges

Voltage supply

Constant

Strain constant

xvii

Chapter 1 Introduction

CHAPTER 1

INTRODUCTION

1.0 Background

There are few developing countries economic depends on their petrochemical

industries. Malaysia itself had invested billion Ringgit for this kind of industries

which was believed that the profit of the investment is encouraging. Thus, the

petrochemical companies that involve with this high capital cost business, it is

important for them to utilize their investment in order to maintain their plant

especially their static and rotating equipment in order to maintain their reliability and

production rate. Static equipment which is a storage tank can be considered to be one

of the most important equipment in petrochemical plant whereby this tank is used to

store liquefied gasses that poisonous, hazardous, flammable and other type of

products. This storage tank is important to store the product before it is exported to

other countries or transfer via pipeline for processes.

To extend and maintain the service life, storage tank requires continuous

coating and inspection in order for the storage tank to be safe from leakage that could

be hazardous and harmful to surrounding human being. Few million spend each year

to maintain and to prevent rusting of their plant storage tank. Thus, the cost will he J Design and Fabrication ol'an Improved

Crack Growth Testing Apparatus with Stress Corrosion Cracking (SC'(') Study


increase annually as the cost of maintenance increased and the preventive periodic

maintenance will only protect the storage tank from outside but not from the inside.

The major problem is when should the storage tank be changed to the new one? Does

the petrochemical company need to wait until the storage tank leaks or collapse

because of stress corrosion?

Proper design, time to time inspection and testing, and preventive periodic

maintenance is necessary but for safety reason the company need to change their

storage time as if the storage tank failure and collapse this will cost the petrochemical

company tremendous economic losses because they have to shut down their plant for

rejuvenation and revamping their storage tank.

Stress corrosion cracking inspection and testing of the storage tank is

important due to some reasons such as human life and safety, loss of product, plant

downtime, contamination, loss of efficiency and customer reliability

2 Design and Fabrication o/ an Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SC'C') Study


1.1 Ammonia Storage tank

The ammonia storage tank designed, capacity and type of material used for

fabricating of the ammonia storage tank depend on the configuration of design

requirements. The ammonia storage tank should be fabricated following the latest

ASME Code requirements and ANSI K61.1 design specifications including Post

Weld Heat Treatment (Stress Relieving) (http: //www. trinitylpg. com/products. asp).

The material that commonly used to fabricate the ammonia storage tank is

stainless steel due to its special characteristic. The main advantages of stainless steel

are high toughness; ease clean ability and immunity to chloride stress corrosion

cracking but it required special care. However, at elevated service temperature will

reduce the toughness of the ammonia storage tank that fabricate by stainless steel. In

addition, the presence of oxygen in liquid ammonia can cause stress corrosion

cracking to the ammonia storage tank.

The 30,000 tan ammonia tank near Gladstone, Queensland, Australia, is a

double integrity tank (cup-in-tank), 40 in in diameter, 36.225 m high; the outer tank

is 42.3 in in diameter, externally insulated, with a spherical roof, and stands on a

piled, insulated, concrete foundation about 600 mm clear of the ground. The

installation is refrigerated and operates at the normal boiling point of ammonia at

- 33°C and has a design pressure of 14 kPa. The tank material is ASTM A516-70

with specified low temperature impact properties and has a maximum thickness of

32 mm at the lowest strake, and a minimum thickness of 10 mm in the upper one-

3 Design and Fabrication o/'an Improved Crack Growth Testing Apparatus with

Stress Corrosion ('racking (SC(') Studs


third of the tank. The tank was designed, supplied and constructed according to the

requirements of BS 7777 (Aneziris et al, 2000)

Figure 1.1: Design of 30000 tones of ammonia storage tank

(http: //www. dcedaust. org/peter3. htm)

4 Design and Fabrication ol'an Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SCC) Study

Chapter I

10 000 t Anutwnia Stora, ere Tank, FACT, Cochin, India

Introduction

Design preewre: 800 mm WG/- 50 mm WG Refrigeration unit: 2x 275 000 Kcal/h

2x 93 000 Kcal/b Flare capacity: 750 Naa/h gas

thermocole 180 shell Aiumininm Out

cladding Foam concrete glass

Crete foundation slab .ýý. ý� ";

Detail 'A'

Figure 1.2: Design of 10000 tones of ammonia storage tank. (Schirmer, 1987)

When operating at the maximum capacity and normal internal vapor pressure

of about 5 kPa, the wall membrane stress is almost constant at 150 MPa in the lower

two-third of the tank wall because of varying wall thickness. While the tank steel

(about 2000 t in total) was purchased to match ASTM A516 Gr70, the actual

mechanical properties exceeded those specified. Actual minimum values were

(compared to minimum specified): yield strength 450 MPa (minimum: 260 MPa),

tensile strength 575 MPa (minimum: 485 MPa), Charpy V-notch toughness >I 00 J at

- 50°C and >140 J at - 33°C (minimum: 50 J at - 50°C), elongation >30% (minimum:

22%) and reduction in area >70% (not specified). (Aneziris et a!, 2000)

5 Design and Fabrication of an Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SC'C') Study

Chapter 1

RELIEF -_ ý- "- \Uf' -ý DECAL

VALVE

REGUALATOR BRACKET

LID _ ASSEMBLY'

COLLAR

Introduction

OVERALL LENGTH

OUTSIDE DIAMETER

FOOT RING

Figure 1.3: Ammonia storage tank design (http: //www. trinitylpg. com)

Design und Fabrication o/'an Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SCC) Studv


1.2 Aim and Objective

The main aim for this study is to study and review on the stress corrosion

cracking (SCC) effect to an industrial ammonia tank which occur to the metallic

material in petrochemical plant. In order to achieve this aim, the author will redesign

and fabricate a new prototype that will be used to examine the crack growth of the

testing specimen. The experimental analysis and testing will be carried out to the

specimen and will be tested by using the new stress corrosion cracking tester

prototype. Different kind of condition will be analyze whereby in presence of

oxygen, vacuum condition (without air and moisture) and in presence of liquefied

ammonia. This is important in this research because those conditions had different

stress corrosion cracking effects to the specimen.

The objectives of this project are:

i) To design an improved Crack Growth Testing Apparatus

ii) To fabricate an improved Crack Growth Testing Apparatus

iii) To examine an improved Crack Growth Testing Apparatus

iv) To demonstrate an Improved Crack Growth Testing Apparatus using

Solidwork 2003 Software

Design and Fabrication o/'un Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SC'C) Studi,

Chapter 2 Literature Review

CHAPTER 2

LITERATURE REVIEW

2.0 Introduction

This chapter will describe on the mechanism of stress corrosion cracking. The

author will focused on the effect of stress corrosion cracking to the hazardous

solution and reaction of certain material to another hazardous solution. Problem and

limitation of the existed prototype included in this chapter to ease to author to

improve and reduce the problem occur. Beside that, this chapter also described the

testing method to fulfill the requirement and obtain the objective of the study. In

order to perform the test, the safety feature for the crack growth apparatus state in

this chapter along with the design software to model the prototype. Another main

subtopic in this chapter is the author will discussed few design approaches that will

be under the author consideration.

$ Design and Fabrication of an Improved Crack Growth Testing Apparatus with

Stress Corrosion Cracking (SC(') Study


2.1 Stress Corrosion cracking

Corrosion had been a major problem to our lives. Majority of us had our own

definition for the corrosion and cause of corrosion. We are all familiar with rusting of

our kitchen appliances, steel household, vehicle, can food, home piping system and

many more. This metal corroded due to reaction with the environment. The main

cause of corrosion is the presence of oxygen and water (moisture).

According to Jones (1996) corrosion is defined as the destructive result of

chemical reaction between a metal or metal alloys and its environment. Metal atones

in nature are present in chemical compounds (i. e., minerals). The same amounts of

energy needed to extract metals from their minerals are emitted during the chemical

reaction that produce corrosion. Corrosion returns the metal to its combined state in

chemical compounds that are similar or even identical to the minerals from which the

metals were extracted. Thus, corrosion had been called extractive metallurgy in

reverse.

And as far as we know, there are many type of corrosion and stress corrosion

cracking is one of them. According to Jones (1992), Stress Corrosion cracking (SCC)

is defined as a brittle failure at a relatively low constant tensile stress of an alloy

exposed to a corrosive environment. In Addition, Fontana (1986) had stated that SCC

refers to cracking caused by the simultaneous presence of tensile stress and a specific

corrosive medium. During stress-corrosion cracking, the metal or alloy is virtually

unattacked over most of its surface, while fine crack progress through it. This


Stress Corrosion ('racking (SCC) Study


cracking phenomenon has serious consequences since it can occur at stresses within

the range of typical design stress.

According to Jones (1992), it had been thought that three condition must be

present simultaneously to produce SCC They are a critical environment, a

susceptible alloy ad some component of tensile stress. Environmental species are

often specific to the alloy system and may not have an effect on other alloys of

different type. For example, hot aqueous chloride solutions readily crack stainless

steel but do not have the same effect on carbon steel, aluminum or other nonferrous

alloys. Not all environments cause cracking of a particular alloy, but new alloy-

environment combinations resulting in SCC are being discovered in a regular basis.

Figure 2.1: Simultaneous Tensile Stress, susceptible metallurgical condition and

critical corrosive solution required for stress corrosion cracking (Jones, 1992)




Hence, Jones (1992) mentioned that although the three factors are not present

together, time and service conditions may conspire to produce the necessary

combinations that result in surprising expensive failures. Boiling and evaporation can

concentrate the critical solutes in very dilute and otherwise nonaggressive solutions.

Tensile stresses even below yield are sufficient to cause SCC and may result from

bolting and fastening parts that fit together imperfectly. Uneven thermal expansion

and contraction can produce residual tensile stresses after welding and other heat

treatments. In addition, SCC is normally associated with static tensile stresses.

However, only slight, long-term variation in loading (e. g., even once loading) are

known to accelerate the onset of SCC. It is uncertain whether such effect should be

attributed to SCC or corrosion fatigue.

Fontana (1986) also stated that for tropical countries, during a period of a

heavy rainfall, crack can propagate quite fast and lead to stress corrosion cracking.

Stress alone reacts in many ways following the mechanical metallurgy such as creep,

fatigue, tensile and failure. Hence, corrosion will react and produce characteristic

dissolution reaction which are the simultaneous action of both and sometimes

produce the disastrous.

11 Design anti Fabrication o/an Improved Crack Growth Testing Apparatus with


ibrahim manai bin abdul hakim and fabrication of an improved cr… · merupakan aspek utama dalam...

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