problems and countermeasures of the quality of …

PROBLEMS AND COUNTERMEASURES OF THE

QUALITY OF FABRICATED STEELWORK IN

THAILAND BUILDING PROJECTS

BY

WATCHARAPHON SAEGOW

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

(ENGINEERING AND TECHNOLOGY)

SIRINDHORN INTERNATIONAL INSTITUTE OF TECHNOLOGY

THAMMASAT UNIVERSITY

ACADEMIC YEAR 2018

Ref. code: 25615922040299ZBX

ii

Abstract

PROBLEMS AND COUNTERMEASURES OF THE

QUALITY OF FABRICATED STEELWORK IN THAILAND

BUILDING PROJECTS

by

WATCHARAPHON SAEGOW

Bachelor of Engineering (Civil Engineering),

Sirindhorn International Institute of technology, Thammasat University, 2015.

Master of Science (Engineering and Technology),

Sirindhorn International Institute of Technology, Thammasat University, 2018.

Nowadays, pre-engineered steel buildings (PEB), which are imported from foreign

countries, become popular for the construction of factories and warehouses in Thailand.

In most of the PEB projects in Thailand, the fabricated parts imported from foreign

countries, have not been properly examined by the concerned Thai authorities or the

third party. This study collects information about imported PEB steel structures. The

method consists of site visiting and interviews of personnel in charge of design and

construction of the imported PEB. In order to perform a comparative study on the

quality of fabricated structures, international inspection standards for fabrication are

adopted in this study. From the inspection results at five imported PEB construction

sites, some defects in the steel structures are found as follows: 1) welding defects such

as undercut, overlap and porosity, 2) defects in anchor bolt such as remaining screw

length less than position of nut, 3) defects in the fabricated part, due to error of

fabrication process such as distortion of area surrounding the holes and insufficient of

coating thickness. The proposed countermeasures for quality control of fabricated steel

structures were divided into two schemes as follows: (a) fabricator accreditation to

classify the fabricator according to their capabilities. (b) checklist for inspection the

quality of fabricated steel structures.

Keywords: Pre-Engineered Steel Buildings (PEB), Steel Structures, Inspection and

Defects

Ref. code: 25615922040299ZBX

iii

Acknowledgement

First of all, I would like to express my gratitude to my upmost appreciation and

sincere gratitude to Assoc. Prof. Dr. Taweep Chaisomphob, my research supervisor,

for his guidance, and valuable suggestions for my research study.

Besides my mentor, I would like to acknowledge the rest of my thesis

committee: Asst. Prof. Dr. Pakawat Sancharoen and Col. Asst. Prof. Dr. Nuthaporn

Nuttayasakul, for their knowledge, encouragements, and comments which motivated

me to widen my knowledge to improve thesis.

Finally, I would like to thank all of my senior students, friends, and companies

(PEB, ATAD, Kirby and BMB) for their assistance, time, strength, and encouragement

which always support me during the tough time. And special thanks go to my parents

for their supports and encouragements in moving forward and completing the thesis.

Ref. code: 25615922040299ZBX

iv

Table of Contents

Chapter Title Page

Signature Page i

Abstract ii

Acknowledgements iii

Table of Contents iv

List of Tables vii

List of Figures viii

1 Introduction 1

1.1 General 1

1.2 Statement of Problems 1

1.3 Objectives of study 2

1.4 Scopes of study 2

2 Literature Review 3

2.1 Steel Structures Damage and Defect 3

2.1.1 Corrosion Damage 3

2.1.2 Welding Defect 3

2.2 Inspection and Evaluation Standard 4

2.2.1 Welding Inspection 4

2.2.2 Bolt Inspection 8

2.2.3 Coating Inspection 9

3 Methodology 10

3.1 Maintenance Personnel Interview 10

3.2 Inspection and Evaluation on Steel Structure 10

3.2.1 Welding Inspection Criteria 11

3.2.1.1 Welding Inspection Equipment 11

Ref. code: 25615922040299ZBX

v

3.2.2 Bolting Inspection Criteria 11

3.2.3 Steel Coating Inspection Criteria 12

3.2.3.1 Steel Coating Inspection Equipment 15

4 Results and Discussion 16

4.1 New Steel Structures (PEB) 16

4.1.1 Data Collection 16

4.1.2 Fabrication Process 16

4.1.3 Material Specification 17

4.1.3.1 Visiting Construction Sites of Pre-Engineered

Buildings (PEB) 17

4.1.3.1.1 Site No.1 18

4.1.3.1.2 Site No.2 20

4.1.3.1.3 Site No.3 22

4.1.3.1.4 Site No.4 24

4.1.3.1.5 Site No.5 28

4.1.3.2 Inspection Result 30

4.1.3.2.1 Welding Defects 30

4.1.3.2.2 Defects of Anchor Bolt 30

4.1.3.2.3 Comparison Result of Steel Thickness 31

4.1.3.2.4 Comparison Result of Coating Thickness 33

4.2 Existing Steel Structures 34

4.2.1 Power Plant A1 34

4.2.1.1 Steel Structure Inspection and Evaluation Results 34

4.2.2 Power Plant A2 39


4.2.3 Steel Billboard A 42


4.3 Survey Fabricator Companies 47

4.3.1 Fabricator in Foreign Country 47

4.3.1.1 PEB Steel Company 47

4.3.2 Fabricator in Thailand 50

Ref. code: 25615922040299ZBX

vi

4.3.2.1 BlueScope Building Company 50

4.3.2.2 M.C.S. Steel Public Company Limited 52

4.3.2.3 T-rex Steel Company Limited 53

4.3.2.4 ST. Frame & Truss Company Limited 55

4.3.2.5 Mano Steel Company limited 56

4.4 Proposed Countermeasure 56

4.4.1 Structural Steel Fabrication Accreditation 56

4.4.2 Checklist for fabricated steelwork 58

4.4.2.1 Material Selection 59

4.4.2.2 Fabrication 59

4.4.2.3 Welding 59

4.4.2.4 Welding Inspection 59

4.4.2.5 Coating 60

4.4.2.6 Erection 60

5 Conclusion 66

5.1 Conclusion 66

5.2 Suggestion of Solutions 66

5.2.1 Fabricators Accreditation 66

5.2.2 Checklist for Inspection Fabricated Steel Structure 67

References 68

Appendices 70

Appendix A 71

Ref. code: 25615922040299ZBX

vii

List of Tables

Tables Page

2.1 Welding Visual Inspection Acceptance Criteria (DPT 1561-51) 5

3.1 Rating scheme for designating the quantity of defects (ISO 4628-1) 12

3.2 Rating scheme for designating the size of defects (ISO 4628-1) 12

3.3 Rating scheme for designating the intensity of changes (ISO 4628-1) 13

3.4 Degree of rusting and rested area (ISO 4628-3) 13

3.5 Rating scheme for designating the quantity of cracks (ISO 4628-4) 13

3.6 Rating scheme for designating the size of cracks (ISO 4628-4) 14

3.7 Rating scheme for designating the quantity of flaking (ISO 4628-5) 14

3.8 Rating scheme for designating the size of areas exposed by flaking

(ISO 4628-5) 14

4.1 Comparisons of material specifications 17

4.2 Description of visited sites 18

4.3 Result of steel thickness 32

4.4 Result of coating thickness 33

4.5 Inspection of coating defect of power plant building 35

4.6 Inspection of welding defect of power plant building 37

4.7 Inspection of bolt defect of power plant building 38

4.8 Inspection of coating defect of power plant building 40

4.9 Inspection of welding defect of power plant building 41

4.10 Inspection of bolt defect of power plant building 41

4.11 Inspection of coating defect of billboard 43

4.12 Inspection of welding defect of billboard 45

4.13 Inspection of bolt defect of billboard 46

4.14 Guidelines of Classification of Thai steel constructors 57

4.15 Equipment of Guidelines of Classification of Thai steel constructors 58

4.16 Checklist for inspection fabricated steel structure 61

Ref. code: 25615922040299ZBX

viii

List of Figures

Figures Page

2.1 Undercut, Porosity and Overlap welds 4

3.1 Taper Gauge 11

3.2 Tape measurement 11

3.3 Welding Gauge 11

3.4 DFT Gauging 15

3.5 Thickness Gauging (UT) 15

4.1 Flow chart of fabrication process 17

4.2 Frame cross section 18

4.3 Overview of site no.1 19

4.4 Part of steel structure in site no.1 20


4.6 Steel structure in site no.2 21

4.7 Defect of steel structure in site no.2 22





4.12 Weld connection of the steel structure in site no.4 26

4.13 Defect of steel section from factory at site no.4 27

4.14 Scratch of anti-corrosive paint at site no.4 27

4.15 Flaking of anti-corrosive paint at site no.4 27



4.18 Weld connection of the steel structure in site no.5 29

4.19 Welding defects found on column and rafter 30

4.20 Defects of anchor bolt 31

4.21 Components of built-up steel section 32

4.22 Overview of Power Plant A1 34

4.23 Overview of Power Plant A2 39

Ref. code: 25615922040299ZBX

ix

4.24 Overview of Billboard A 42

4.25 Fabrication process of PEB Company 49

4.26 Fabrication process of BlueScope Building Company 52

4.27 Fabrication process of MCS 52

4.28 Fabrication process of T-Rex Steel Company 54

4.29 Fabrication process of ST. Frame & Truss Company 55

A-1 Blistering of size 2 63

A-2 Blisters of size 3 64



A-5 Degree of rusting Ri 1 67





A-10 Cracking without preferential direction 70

A-11 Cracking with preferential direction 79

A-12 Flaking without preferential direction 80

A-13 Flaking with preferential direction 81

Ref. code: 25615922040299ZBX

1

Chapter 1

Introduction

1.1 General

Steel structures had been used widely in Thailand, espectually Pre-engineered

steel buildings (PEB) is a metal building designed and fabricated in the factory

premises; all components are shipped to site and are assembled and erected at site with

nuts, bolts and anchor bolts. The advantages of PEB are high durability, fast erection,

and cost saving. Particularly PEB as the latest trend in building construction are

increasingly confirmed their outstanding advantages in industrial and commercial

projects such as factory, warehouse, cold storage, showroom, office, supermarket,

school, stadium.

Durability of steel structure constructed is an important issue to be consider by

an engineer who desired long-lasting service life of the structures. So, good

maintenance system is highly essential to maintain durability of a structure.

It’s important to keep monitoring a steel structure to prevent the structural

failure, either by damage from deterioration during service life, or damage from defect

before or after construction process, or both type of damage.

.

1.2 Statement of Problem

We have not to control over the quality of fabrication and erection. In this

research, we have determined the problems of steel structure and solutions as follows;

1. Steel imported from foreign countries do not good quality.

2. Steel structures are imported from foreign countries that are not standard and

quality control has been erection in Thailand.

3. Steel constructors do not have the expertise and capability to manufacture of

large scale or poor workmanship such as welder and erector.

1.3 Objective of Study

The objective of this research is:

1. Establishment of construction guidelines for new steel structure

1.1 Inspection new structures imported from foreign country

2. Establishment of inspection guidelines for existing steel structure

2.1 Inspection steel structures in Thailand

Ref. code: 25615922040299ZBX

2

1.4 Scope of Study

The scope of this research is:

1. visited some factories to inspected from foreign country and propose guideline

to inspect.

2. Inspection new structures imported from foreign country

3. Inspection existing steel structures in Thailand

Ref. code: 25615922040299ZBX

3

Chapter 2

Literature Review

2.1 Steel Structures Damage and Defect

2.1.1 Corrosion Damage

Mars G. Fontana (1987) revealed that corrosion is the deterioration of a material

occur on the reaction with an environment which can be classified into “Wet corrosion”

and “Dry corrosion”. Wet corrosion occurs like the corrosion of steel by water. Dry

corrosion like the attack on steel by furnace gases. Small amounts of moisture can

highly affect the severity of the corrosion, like when moist chlorine or chlorine

dissolved in water is extremely corrosive comparing to dry chlorine which is

noncorrosive to steel.

corrosion damage is decreasing of steel section thickness. The corrosion

damage can affect the cost of the structure and the material to more resistance to its

condition can save the total cost, also many steel structures are stopped corrosion

failure. Inspection helps to protect the corrosion failure in structure.

2.1.2 Welding Defects

Baughurst et al. (2009) revealed that welding could be inefficient for its

purpose. which involve with the welding, such as overlap (Fig 2.1b) is caused by poor

welding techniques.

But there are more severe types of defects which can highly affect the capacity

of the weld such as cracking, undercutting (Fig 2.1a) which is an unfilled groove weld,

and Porosity (Fig 2.1c) which cause of problem for Cracking.

a) Undercut

Ref. code: 25615922040299ZBX

4

b) Overlap

c) Porosity

Fig 2.1 Undercut, Porosity and Overlap welds

2.2 Inspection and Evaluation Standards

2.2.1 Welding Inspection

“Structural Steel welding inspection standard using Non-destructive testing” is

the standard to inspect the welding connection of steel connection is called DPT 1561-

51: using Visual inspection and equivalent to American Welding Society (AWS

D1.1/D1.1M).

DPT 1561-51 is criteria for VT to check the welding defect according to the

type of defect such as crack, porosity, and undercut, etc.

All welds should be visually inspected 100 percent based on DPT 1561-51

shown in Table 2.1.

Ref. code: 25615922040299ZBX

5

Table 2.1 Welding visual inspection acceptance criteria (DPT 1561-51)

Ref. code: 25615922040299ZBX

6

Table 2.1 Welding visual inspection acceptance criteria (DPT 1561-51) (Continue)

Ref. code: 25615922040299ZBX

7


Ref. code: 25615922040299ZBX

8


2.2.2 Bolt Inspection

JASS 6 state that, for bolt, after tightening process the bolt connection should

be inspected, to check the quality, size, and tightness level of the bolt. The tightening

check can be simply done by using torque wrench. Over-tightened bolt shall be

replaced, and loose bolt shall be tightened correctly.

JIS B 1186 state that, for high strength hexagon bolt, nut, and washers shall be inspected

to ensure the properties of the bolt connection such as, Shape and dimension using

direct measurement, appearance of the bolt such as the surface defect test using liquid

penetrant testing or magnetic particle testing to indicate the crack. Also, the mechanical

properties of the bolt shall be tested using bolt test pieces as a sample of bolt, nut, and

washer.

Finally, the joint shall be visually verified the faying surface of slip-critical joint

whether it meets the specification or not.

2.2.3 Coating Inspection

ISO 4628 state the general designation system for paint and varnishes

evaluation of degradation of coating based on quantity and size of defects and the

intensity of change by means of ratings on a numerical scale ranging from 0 to 5, while

“0” means “No defects”, and “5” means “Very severe”. The rest of the rating (1, 2, 3,

4) corresponds the severity range from low to high severity. Coating shall be inspection

visually to indicate the defects and its severity level. ISO 4628 specified the assessment

of degree of blistering, rusting, cracking, flaking of paint accordingly, Photographic

Ref. code: 25615922040299ZBX

9

reference is given for each defect type based on quantity and size of defect, as shown

in Appendix A.

Ref. code: 25615922040299ZBX

10

Chapter 3

Methodology

To indicating the damage and defect that occurred to steel structure, and to

identify the cause of the damage, Real site inspection and interview of maintenance

personnel are necessary to obtain enough information that leads to the countermeasure

to solve and prevent the damage. The target structures were steel billboards and steel

buildings.

3.1 Maintenance Personnel Interview

Information about the construction site, problem, and maintenance of the

damaged steel structures is to interview the maintenance personnel. This information

helps on identify indirect and root cause of the defect for steel structure in Thailand.

There are no specific questions that were asked in the interview, the interview was

carried out as a a topic or issues about the maintenance work, damage occurred on the

steel structures, and the opinion on a topic such as Thailand standards and guideline of

construction system in Thailand. These questions were asked to inspect steel structure.

And to obtain some knowledge about how to improve the steel structure maintenance,

standards and guideline of steel structure construction system in Thailand.

3.2 Inspection and Evaluation on Steel Structures

Visiting the real construction site is the best way to acknowledge the damage or

defect that occurred to steel structures. Site inspections were mostly carryout by using

visual inspection, coating thickness and steel thickness, since this method does not

affect property, appearance, or function of the structures. Visual inspection routine used

in this research, the visual inspection and evaluation was divided in to two target areas

which are steel connection inspection and steel surface inspection. The steel connection

inspection was focused on both of weld and bolt connection based on DPT 1561-51 and

JASS 6 accordingly. Steel surface inspection was focused on coating thickness and

corrosion on the steel surface based on ISO 4628.

Ref. code: 25615922040299ZBX

11

3.2.1 Welding Inspection Criteria

In this research, visual inspection method was used to inspect the steel structure

with welded connections, which was considered to be the most severe welding defects.

The welding inspection criteria are according to the criteria in DPT 1561-51.

3.2.1.1 Welding Inspection Equipment

The equipment for welding inspection was listed below:

1. Taper Gauge (Shown in Fig 3.1)

2. Tape measurement (Shown in Fig 3.2)

3. Welding Gauge (Shown in Fig 3.3)

Fig 3.1 Taper Gauge Fig 3.2 Tape measurement Fig 3.3 Welding Gauge

3.2.2 Bolting Inspection Criteria

According to JASS 6 that bolt inspection for every bolt after tightening is

necessary and need to all of bolt that tightening. But this research is targeted Pre-

engineered steel building (PEB) and existing steel structure makes difficulty on getting

those certain structure design data or drawing, so it impossible to follow the criteria

about JASS 6 directly. Bolting inspection criteria was to check the appearance of the

bolt connection. The criteria were to VT check the damage on the bolt connection such

as bolt connection surface damage, bolt connection deformation, the length of bolt

beyond nuts is too short, and bolt connection failure.

3.2.3 Steel Coating Inspection Criteria

The inspection criteria for steel coating are used in this research was followed

the international standard ISO 4628. The inspection carried out by using visual

inspection and photographic reference (shown in Appendix A), and then recorded the

Ref. code: 25615922040299ZBX

12

inspection data in the charge of photograph and table. The data was evaluated based on

the quantity, size, and intensity of change of each defect according to ISO 4628. The

coating damage was evaluated by using the table and photograph as shown in Table 3.1

until Table 3.8 and comparing with reference in Appendix A.

Table 3.1 Rating scheme for designating the quantity of defects (ISO 4628-1)

Table 3.2 Rating scheme for designating the size of defects (ISO 4628-1)

Ref. code: 25615922040299ZBX

13

Table 3.3 Rating scheme for designating the intensity of changes (ISO 4628-1)

Table 3.4 Degree of rusting and rested area (ISO 4628-3)

Table 3.5 Rating scheme for designating the quantity of cracks (ISO 4628-4)

Ref. code: 25615922040299ZBX

14

Table 3.6 Rating scheme for designating the size of cracks (ISO 4628-4)

Table 3.7 Rating scheme for designating the quantity of flaking (ISO 4628-5)

Table 3.8 Rating scheme for designating the size of areas exposed by flaking (ISO

4628-5)

Ref. code: 25615922040299ZBX

15

3.2.3.1 Steel Coating Inspection Equipment

The equipment used in steel coating inspection was listed as follow:

1. Tape measurement (Shown in Fig 3.2)

2. Camera

3. Reference photo (from ISO 4628)

4. Dry Film Thickness (DFT) Gauging (Shown in Fig 3.4)

5. Thickness Gauging (UT) (Shown in Fig 3.5)

Fig 3.4 DFT Gauging Fig 3.5 Thickness Gauging (UT)

3.3 Survey Fabricator Companies

The Fabricator is the primary responsibility for ensuring the structural steelwork

is manufactured to the requirements of the contract documents. They must operate some

form of production control system, which will include:

• Fabricator production control system

• Traceability and component marking

• Weld quality management

• Acceptance of material (Structural steels, weld consumables, bolts)

• Fabrication processes (milling, drilling, cutting and coating)

• Inspection and testing method (VT, UT, RT for heavy industry and PT)

Ref. code: 25615922040299ZBX

16

Chapter 4

Results and Discussion

4.1 New Steel Structures (PEB)

4.1.1 Data Collection

We have visited four companies to collect data on PEB such as design,

fabrication, erection and also interviewed engineers who are responsible for design and

construction. These four companies are the international companies in which their

fabrication factories are located outside Thailand, they are named as company A, B, C

and D. We went to visit the headquarter (Company A) of one company in the foreign

country and the branch of other three companies (Company B, C, D) in Thailand.

For the design method, most of the companies use the Allowable Strength

Design (ASD) and loading conditions as follows:

1. Dead load consists of the weight of all material of construction incorporated

into the building.

2. Roof Live Loads, for built-up frames minimum uniformly distributed live load

on roof is 0.57kN/m2 according to MBMA.

3. Collateral loads are included in roof live loads that arise due to sprinklers, ducts,

lighting fixtures and ceilings.

4. Wind loads are governed by wind speed, roof slope, eave height and open wall

conditions of the building. PEB are designed for a minimum wind speed of a 110 km/hr.

more than DPT 1511 (Department of Public Works and Town & Country Planning,

Thailand).

4.1.2 Fabrication Process

The fabrication process of the components of PEB companies are shown in

Fig.4.1. The first step begins with preparation of raw material. Second step is

cutting/drilling and punching by plasma and flame method. Third step is tacking web

and flange built up into H-Beam, after that auto welding by a submerged arc welding

process (SAW). Fourth step is fitting and final welding by a gas metal arc welding

process (GMAW) or Flux core arc welding process (FCAW). The last step is blasting

two surface profiles including SA2.0 and SA2.5 according to ISO 8501-1, and coating

with a quick drying primer.

Ref. code: 25615922040299ZBX

17

Fig.4.1 Flow chart of fabrication process

4.1.3 Material Specification

From the results of collecting data at 4 companies, it was found that the

international standards such as USA and Japan are used for material selection of the

frame structure as shown in Table 4.1.

Table 4.1 Comparisons of material specifications

Material Company A Company B Company C Company D

1.Built-up member ASTM A572

Gr 50

ASTM A572

Gr 50 Q 345 (GB)

Q 345 (GB) or

ASTM A 572

Gr.50

2.X-Bracing rod ASTM A 36 JIS G3101/

SS400 ASTM A36

JIS SS 400 or

ASTM A36

3.Anchor bolt ASTM A 36

(Gr. 4.6)

TCVN 1916-

1995

ASTM A36

(Gr. 4.6)

ASTM A36

(Gr. 4.6)

4.High strength bolt ASTM A 325

(Gr 8.8)

ASTM A490

(Gr 10.9)

ASTM A325

(Gr8.8)

ASTM A325

(Gr8.8)

4.1.3.1 Visiting Construction Sites of Pre-Engineered Buildings (PEB)

Generally, PEB will be constructing by using a built-up member and it is a metal

building designed and was welded from fabrication in the factory premises; all

components are shipped to site and are assembled and erected at site using bolt

connection (nuts, bolts and anchor bolts).

Five construction sites were visited: two construction sites in a foreign country

(site no.1, 2) and three construction sites in Thailand (site no. 3, 4, 5). The dimension

and some description of the visited sites are illustrated is Fig.4.2 and Table 4.2

Ref. code: 25615922040299ZBX

18

Fig.4.2 Frame cross section

Table 4.2. Description of visited sites

Site No. Type Description of Site Dimension of PEB

X (m) Y (m)

1 Garment

Factory

Fabricated by company A

Erected in the foreign country

60 10

2 Furniture

storage

Fabricated by company A

Erected in the foreign country

60 6

3 Coal

storage

Fabricated by company B

Erected in Thailand

60 14.4

4 Warehouse Fabricated by company C

Erected in Thailand

48 8

5 Warehouse Fabricated by company D

Erected in Thailand

30 9.8

4.1.3.1.1 Site No.1

Site no.1 is a Garment Factory located in Vung Tau province, Vietnam. The

structural steel was fabricated from the factory in Vietnam, and then erected at the site

in Vietnam.

Fig. 4.3 shows the overall of construction site no.1, Fig 4.4 a) shows the anchor

bolt using double nut and 1 washer according to MBMA, and Fig.4.4 b) and c) shows

some part of the steel structure consist of column and rafter.

Ref. code: 25615922040299ZBX

19

Fig 4.3 Overview of site no.1

a) Anchor bolt using double nut and 1 washer

b) Rafter component

Ref. code: 25615922040299ZBX

20

c) Column component

Fig 4.4 Part of steel structure in site no.1

4.1.3.1.2 Site No.2

Site no.2 is a furniture storage warehouse that located in Dong Nai province,

Vietnam. The structural steel was fabricated from the factory in Vietnam, and then

erected at the site in Vietnam.

Fig 4.5 shows the overview of the steel structures in site no.2, Fig 4.6 a) shows

the anchor bolt using double nut and 1 washer according to MBMA, Fig.4.6 b) shows

rafter and column connected by bolt. Component of column in site no.2 was thoroughly

inspected base on visual inspection is shown in Fig.4.7 shows defect of anchor bolt are

unacceptable (see 4.2.1).


Ref. code: 25615922040299ZBX

21


b) Rafter and column connected by bolt

Fig 4.6 Steel structure in site no.2

a) Defect of anchor bolts

Ref. code: 25615922040299ZBX

22

b) Defect of anchor bolts (single nut)

Fig 4.7 Defect of steel structure in site no.2

4.1.3.1.3 Site No.3

Site no.3 is a coal storage located in Ayutthaya province, Thailand. The


in Thailand, Fig.4.8 shows overall of construction site no.3.


Fig 4.8 shows the overview of the steel structures in site no.3, Fig 4.9 a) shows

the anchor bolt using double nut and 1 washer according to MBMA, Fig.4.9 b) shows

rafter and purlin erection and Fig.4.9 c) shows installation rafter using bolt tightening

by Torque wrench.

Ref. code: 25615922040299ZBX

23


b) Erection rafter and purlin

Ref. code: 25615922040299ZBX

24

c) Bolt installation by torque wrench


4.1.3.1.4 Site No.4

Site no.4 is a warehouse located in Chonburi province, Thailand. The structural

steel was fabricated from the factory in Vietnam, and then erected at the site in

Thailand.

Fig 4.10 shows the overview of the steel structures in site no.4, Fig 4.11 a)

shows the Component of rafter, purlin and roof after installation, Fig.4.11 b) shows

rafter and column connected by bolt.


Ref. code: 25615922040299ZBX

25

a) Component of rafter, purlin and roof after installation



Component of rafter and column in site no.4 was thoroughly inspected base on

visual inspection. The inspection results show many serious weld defects especially

porosities, undercuts and spatters at the welding, as in the figure shows the location of

defect (see Fig 4.12).

Ref. code: 25615922040299ZBX

26

a) Porosity defect

b) Spatter defect

c) Undercut defect

Fig.4.12 Weld connection of the steel structure in site no.4

Ref. code: 25615922040299ZBX

27

The visual inspection show that the steel structure has minor deterioration such

as flaking, intensive change in appearance (color), scratch and defect from factory,

shown in Fig.4.12 to Fig.4.15.

Fig.4.13 Defect of steel section from factory at site no.4

Fig.4.14 Scratch of anti-corrosive paint at site no.4

Ref. code: 25615922040299ZBX

28

Fig.4.15 Flaking of anti-corrosive paint at site no.4

4.1.3.1.5 Site No.5

Site no.5 is a warehouse located in Samutprakarn province, Thailand. The


in Thailand, Fig.4.16 shows overall of construction site no.5.


Fig 4.17 a) shows the anchor bolt using double nut and 1 washer according to

MBMA, Fig.4.17 b) shows rafter and column connected by bolt

Ref. code: 25615922040299ZBX

29




The inspection shows the damage from the welding process during the

construction in factory, the arc of the weld was melted the steel section out and

penetrated the steel section as shown in Fig.4.18.

a) Undercut defect

Ref. code: 25615922040299ZBX

30

b) Imperfect welding

Fig.4.18 Weld connection of the steel structure in site no.5

4.1.3.2 Inspection Result

4.1.3.2.1 Welding Defects

From the inspection results, it was found that some steel structures have defects

of welding on the steel surface, especially incomplete fusion, spatter, porosity, and

undercut, which exceed the standard limit in DPT 1561 (Department of Public Works

and Town & Country Planning, Thailand), which is equivalent to AWS D1.1/D1.1M.

The evaluation of the weld defects was classified as unacceptable. Examples of the

welds that were unacceptable for some sites are shown in Fig.4.19.

a) Welding defects on rafter at site no. 4

b) Welding defects on column at site no. 5

Fig.4.19 Welding defects found on column and rafter

porosit

y

spatte

r incomplete fusion

undercut

imperfect

welding undercut

Ref. code: 25615922040299ZBX

31

4.1.3.2.2 Defects of Anchor Bolt

From the inspection results, it was found that there are the defects of anchor bolt

at site no.2. It was evaluated that the bolt was unacceptable because the length of bolt

beyond nuts is too short, i.e. less than 3 threads, according to JASS 6 as shown in

Fig.4.20 a). In addition, single nut is used as shown in Fig.4.20 b), but according to

MBMA, double nut must be adopted.

a) Defect of anchor bolts

b) Defect of anchor bolt (single nut)

Fig.4.20 Defects of anchor bolt

4.1.3.2.3 Comparison Result of Steel Thickness

In this study, we measured steel thickness of a steel parts (column, rafter) as

shown in Fig.4.21. The inspection of steel thickness was done by using ultrasonic pulse-

echo testing (UT) in Fig.3.4 according to ASTM E797, the results of steel thickness

measurement are compared with the thickness specified in the as-built drawing (Table

4.3), From Table 4.3, it can be seen that the measured steel thickness is more than the

thickness specified in the drawing, and the results are acceptable.

single nut

remaining screw length less than

position of nut.

Ref. code: 25615922040299ZBX

32

Fig.4.21 Components of built-up steel section

Table 4.3 Result of steel thickness

Inspected part

Thick.

Specified

in the

drawing

(mm)

Measured Value (mm)

Average

(mm)

S.D.

(mm)

Difference

(%) Evaluation

x1 x2 x3 x4 x5

Site no.1

Column Web 6 5.98 5.9 6.5 6.2 6.7 6.7 0.13 1% OK

Flange 8 8.07 8.2 8.6 7.9 8.5 8.2 0.29 3% OK

Site no.2

Column Web 6 6 5.5 6 6.2 6.1 6.2 0.26 0% OK

Flange 8 8.6 8.2 8.7 8.9 8.2 8.5 0.32 7% OK

Site no.3

Column Web 10 11.7 11.6 11.4 11.2 12.6 11.6 0.34 16% OK

Flange 10 11.5 10.6 11.1 11.9 10.7 11.2 0.54 12% OK

Site no.4

Column Web 8 8.7 8.7 8.9 8.9 8.7 8.8 0.1 10% OK

Flange 10 10.8 10.5 10.5 10.6 11.5 10.8 0.4 8% OK

Rafter Web 8 9.8 9.1 9.3 9.4 9.2 9.2 0.16 15% OK

Flange 10 10.9 10.8 10.7 10.9 10.6 10.8 0.12 8% OK

Site no.5

Column Web 5 5.3 5.7 5.9 5.3 5.6 5.6 0.24 11% OK

Flange 10 10.3 11.7 10.9 10.4 10.9 10.8 0.57 8% OK

Rafter Web 5 5.7 5.7 5.9 5.5 6 5.7 0.27 14% OK

Flange 10 10.8 10.5 10.3 10.6 10.6 10.7 0.18 6% OK

Flange

Web

Ref. code: 25615922040299ZBX

33

4.1.3.2.4 Comparison Result of Coating Thickness

We measured coating thickness of a steel parts (column, rafter) as shown in

Fig.4.21. The inspection of coating thickness was made by using NDFT by coating

thickness gauge in Fig.3.5 according to ISO 19840. The results of coating thickness

measurement results are compared with the required thickness (Table 4.4). From Table

4.4, it was found that the coating thickness at some sites is less than the required

thickness. Therefore, the quality control on coating process must be seriously

performed at the fabrication factory.

Table 4.4 Result of coating thickness

Inspected part

Thick.

specied in

the drawing

(µm)

Measured Value (µm) Avera

ge

(µm)

S.D.

(µm)

Difference

(%)

Evalua

tion x1 x2 x3 x4 x5

Site no.1

Column Web

80 87 88.4 90.2 85.7 100 90.3 5.7 13% OK

Flange 80.5 82 94.5 81.7 92.4 86.2 6.7 8% OK

Site no.2

Column Web

80 100.4 107.2 102.8 83 82 95.1 11.8 19% OK

Flange 102 89.2 102.2 91.4 95.4 96 6 20% OK

Site no.3

Column Web

660 935 883 1052 1224 979 1014.6 132 54% OK

Flange 510 666 636 640 603 611 60.7 -7% NG

Site no.4

Column Web

660

256.3 249.8 258.8 253.1 215.5 246.7 17.8 -63% NG

Flange 179.9 222.1 209.1 193.8 188.2 198.6 16.9 -70% NG

Rafter Web 263.4 236.6 230.3 239.3 218.5 237.6 16.5 -64% NG

Flange 202.4 185 230.8 218.8 210.7 209.5 17.3 -68% NG

Site no.5

Column Web

80

105 115.6 102.4 110 111.2 108.8 5.2 36% OK

Flange 91.1 101.1 100 95.4 96.3 96.8 4 21% OK

Rafter Web 80.2 85.4 90.5 90 88.5 86.9 4.3 9% OK

Flange 98.4 95.2 94.6 96.3 98.2 96.5 1.8 21% OK

Ref. code: 25615922040299ZBX

34

4.2 Existing Steel Structures

4.2.1 Power Plant A

The steel structure in Power Plant A1 was a constructed by hot-rolled steel as

the main structure connected by bolt connection, so the main damage for the structure

in Power Plant A1. Shown in Fig 4.22 is the steel structure in Power Plant A1.

Fig 4.22 Overview of Power Plant A

4.2.1.1 Steel Structure Inspection and Evaluation Results

The results show that the steel structures had severe damage on the steel

building and bolt connections. The corrosion covers large area on the steel surface and

steel section and some of area has no coating on the steel surface, because of the

corrosion on steel surfaces is severe rust.

The damage could occur from poor workmanship during erection and coating

works, because some area of steel could be unprotected, because of the paint may not

cover the area of the steel, especially at the connection area, so the moisture is cause of

severe corrosion. Table 4.5 shown inspection data based on ISO 4628 standard.

Ref. code: 25615922040299ZBX

35

Table 4.5 Inspection of coating defect of power plant building

Defect Location of defect Useful

Life

(yr)

Criteria Detail of

inspection

Rust Point A

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

Checking steel

thickness and

coating

thickness

Blistering

Column A

10 0 S 0

1 S 1

2 S 2

3 S 3

4 S 4

5 S 5

Checking steel

thickness and

coating

thickness

Ref. code: 25615922040299ZBX

36

Table 4.5 Inspection of coating defect of Power Plant Building (Continue)

Defect Location of defect Useful Life

(yr)

Criteria Detail of

inspection

Flaking

Column A

10 0 S 0

1 S 1

2 S 2

3 S 3

4 S 4

5 S 5

Checking steel

thickness and

coating

thickness

Ref. code: 25615922040299ZBX

37

The steel structure in Power Plant A1 was welded, bolted, and painted at the

site. This explain steel structure in Power Plant A1 have a lot of defect. However, weld

and bolt connection were unacceptable (shown in Table 4.6 and Table 4.7), but poor

paint workmanship could cause a lot of problem to the steel structure.

Table 4.6 Inspection of welding defect of power plant building


(yr)

Cause Detail of inspection

Cracking - - - -

Underfill

10 Poor welder -

Undercut

10 Poor welder -

Ref. code: 25615922040299ZBX

38

Table 4.7 Inspection of bolt defect of power plant building


Life

(yr)

Cause Detail of

inspection

Is the bolt

loosening?

10 Bolt are not

tightening

Checking bolt

tightening by

using hammer

method from

EXACT manual

Is the bolt

quality and

size correct?

10 Material low

quality

-

Checking

bolt nut or

rivet

10 Poor

workmanship

-

Rust

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

-

Ref. code: 25615922040299ZBX

39

4.2.2 Power Plant A

The steel structure in Power Plant A was a constructed by hot-rolled steel as

connected by bolt connection, the structure was located near the water river, so the main

damage for the structure in Power Plant A2. Shown in 4.23 is the steel structure in

Power Plant A.

(a) Steel Structure in Power Plant A2

(b) Steel Structure in Power Plant A2

Fig 4.23 Steel Structure in Power Plant A2

Ref. code: 25615922040299ZBX

40


The visual inspection results are shown that the steel structure have minor

deterioration of anti-corrosive paint, welded and bolted, such as blistering (from high

moisture), flaking, and cracking, causing damage shown in Table 4.8 to Table 4.10



Life

(yr)

Criteria Detail of

inspection

Rust

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

Checking steel

thickness and

coating

thickness

Flaking

10 0 S 0

1 S 1

2 S 2

3 S 3

4 S 4

5 S 5

Checking steel

thickness and

coating

thickness

Ref. code: 25615922040299ZBX

41



(yr)

Cause Detail of

inspection

Cracking - - - -

Underfill

10 Poor welder -



(yr)

Cause Detail of

inspection

Rust

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

-

Rust

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

-

Ref. code: 25615922040299ZBX

42

4.2.3 Steel Billboard A

In this research, steel billboard which located in Samutprakarn area was visually

inspected, the billboard owner in negative ways, the billboard will be named as

“Billboard A”. The inspection criteria were carried out by using the acceptation criteria

in Thai standard for welding visual inspection, and ISO 4628 for steel coating

inspection. Fig 4.24 shows the overview to the structure of Billboard A.

Fig 4.24 Structure overview of Billboard A

Ref. code: 25615922040299ZBX

43


The inspection results show defects such as flaking, blistering, undercut,

porosity and rusting, as well as the inspection and evaluation results were recorded in

as shown in Table 4.11 to Table 4.13.



Life

(yr)

Criteria Detail of

inspection

Rust

2 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

Checking steel

thickness and

coating

thickness

Blistering

2 0 S 0

1 S 1

2 S 2

3 S 3

4 S 4

5 S 5

Checking steel

thickness and

coating

thickness

Ref. code: 25615922040299ZBX

44

Table 4.11 Inspection of coating defect of power plant building (Continue)


Life

(yr)

Criteria Detail of

inspection

Flaking

2 0 S 0

1 S 1

2 S 2

3 S 3

4 S 4

5 S 5

Checking

steel

thickness

and

coating

thickness

Ref. code: 25615922040299ZBX

45



(yr)

Cause Detail of inspection

Cracking - - - -

Underfill

10 Poor welder -

Undercut

10 Poor welder -

Ref. code: 25615922040299ZBX

46



(yr)

Cause Detail of

inspection

Checking

bolt, nut

or rivet

10 Poor

workmanship

Rust

10 Ri 0

Ri 1

Ri 2

Ri 3

Ri 4

Ri 5

-

Ref. code: 25615922040299ZBX

47

4.3 Survey Fabricator Companies

In this visiting five fabricator in Thailand and one fabricator in foreign country

which fabricated steel structures, we have interviewed the personnel who respond for

fabrication process and inspect the quality of steel structures.

4.3.1 Fabricator in Foreign Country

4.3.1.1 PEB Steel Company

PEB Steel Company is the leading PEB Company in Thailand. Established in

1994, PEB Steel Company specializes in the Design, Fabrication, and Erection of Pre-

Engineered Steel Buildings (PEB), steel structures for factories, warehouses. PEB

Company are designed in compliance with the design and building codes (IBC 2015,

AWS 2015, AISC 2016, MBMA 2012, AISI 2013) and PEB Company have

management system such as ISO 9001:2015 and OHSAS19001:2007

The fabrication process of the components of PEB companies are shown in

Fig.4.25. The first step begins with preparation of raw material (ASTM A572 Gr.50) as

shown in Fig.4.25 (a). Second step is cutting/drilling and punching by plasma and flame

method as shown in Fig.4.25 (b and c). Third step is tacking web and flange built up

into H-Beam, after that auto welding by a submerged arc welding process (SAW) as

shown in Fig.4.25 (d). Fourth step is fitting and final welding by a gas metal arc welding

process (GMAW) or Flux core arc welding process (FCAW) as shown in Fig.4.25 (e

and f). The last step is blasting two surface profiles including SA2.0 and SA2.5

according to ISO 8501-1, and coating with a quick drying primer (Single Coat 40

microns for alkyd and 80 microns for epoxy) as shown in Fig.4.25 (g and h).

a) Raw Material

Ref. code: 25615922040299ZBX

48

b) Cutting Steel Plate

c) Drilling and Punching

d) Auto Welding Line

e) Fitting Section

Ref. code: 25615922040299ZBX

49

f) Final Welding and Finishing

g) Shot Blasting Machine ( to clean Steel Member )

h) Painting Area

Fig.4.25 Fabrication process of PEB Company

Ref. code: 25615922040299ZBX

50

4.3.2 Fabricator in Thailand

4.3.2.1 BlueScope Building Company

BlueScope Building Company is one of the PEB Company in Thailand.

BlueScope Building Company specializes in the Design, Fabrication, and Erection of

Pre-Engineered Steel Buildings (P.E.B) in Rayong province Thailand, BlueScope

Building Company are designed in compliance with the design and building codes (IBC

2015, AWS 2015, AISC 2016, MBMA 2012, and AISI 2013) and BlueScope Building

Company have management system such as ISO 9001:2015, SSSS Class S1 and

OHSAS19001:2007.

The fabrication process of the components of BlueScope Building Companyare

shown in Fig.4.26. The first step is stock inventory raw material (steel plate SM520B)

and supply to cutting in CNC plasma line and Flame cutting. Second step is

cutting/drilling and punching by Plasma machine cutting. Third step is assembly of

built-up component into H-Beam, after that auto welding by a submerged arc welding

process (SAW). Fourth step is fitting and final welding by a gas metal arc welding

process (GMAW). The last step is blasting two surface profiles including SA2.0 and

SA2.5 according to ISO 8501-1, and coating with a quick drying primer (Single Coat

50 microns, Multi coat 80 microns and Fire proofing 500 microns).

a) Raw Material

Ref. code: 25615922040299ZBX

51

b) CNC Plasma Machine

c) Flame Planner Machine

d) Tack Station Line

e) Auto Welding

Ref. code: 25615922040299ZBX

52

Cutting Drilling Built-up Welding Blasting Coating

f) Fitting-up and Final Welding

g) Shot Blasting

h) Painting Booth

Fig.4.26 Fabrication process of BlueScope Building Company

4.3.2.2 M.C.S. Steel Public Company Limited

M.C.S. Steel Public Company Limited is the leading steel fabricating Company

in Thailand and the company in Ayutthaya. Established in 1992, M.C.S. has more than

20 years of successful experiences in fabrication of high-rise steel structure building,

power plant, bridge & general steel works. With the most advanced manufacturing

equipment, high standards & punctuality, we are now able to provide & export steel

structure works for various projects worldwide, mainly in Japan with 50,000 tons per

annual. The fabrication process of this company as show in Fig 4.27

Fig 4.27 Fabrication process of MCS

Ref. code: 25615922040299ZBX

53

4.3.2.3 T-rex Steel Company Limited

T-Rex Steel is one of Thailand's leading manufacturer of steel and grating

products. T-Rex Steel are a leader in the design and improvements of steel and grating

products. T-Rex Steel are designed and manufactured to exacting standards,

incorporating the latest technique in high tensile structure design and fabrication. With

over twenty year of experience in manufacturing multi – products, T-Rex Steel offer

internations class for Building Structure, Machine part Structure, Automotive Structure

and Grating. Automotive Structure have management system such as ISO 9001:2015,

and SSSS Class S2.

Fabrication process, T-Rex Steel imported the steel from Hong Kong but steel

plate and steel section such as H and I Section they have bought from LPN plate mill

public company limited and Siam Yamato Steel Company. They focus on the welding

process as much as they can because of this process is the critical point of the

fabrication, they have 3 machines for cutting steel plates and pipes such as CNC cutting

machine, plasma cutting machine, and saw cutting machine as show in Fig 27, they will

cut steel plate, dimension depends on the shop drawing, before fabrication process.

Next, the inspection process, they use UT and PT to inspect the structural product.

Blasting, they will be blasting before coating and painting. Coating and painting

process, they are coating a primer color around 35-50 microns then painting epoxy

around 60-65 microns and the last one is painting color around 30 microns (it depends

on the specification of customer).

a) Raw Material (from SYS and LPN)

Ref. code: 25615922040299ZBX

54

b) Cutting

c) Punching and Drilling

d) Welding Process

e) Steel Grit Blasting (steel grid) and Painting

Fig 4.28 Fabrication process of T-Rex Steel Company

Ref. code: 25615922040299ZBX

55

4.3.2.4 ST. Frame & Truss Company Limited

ST. Frame & Truss was established in 1992.The company specializes in the fabrication

and election of the steel structures for factories, warehouse, commercial/trade center, etc.

During, more than decades of the operation in the field of steel structures industry, we are very

confident that the management is well qualified to prove the best service at the mentioned.

Fabrication process as show in below.

Fig 4.29 Fabrication process of ST. Frame & Truss Company

Ref. code: 25615922040299ZBX

56

4.3.2.5 Mano Steel Company limited

Mano Steel was founded in 2003, we are a specialist in steel structure and

construction and obtained and ISO 9001 certificate, Mostly, we have been working with

Japanese companies such as Thai Shimizu, Thai Obayashi, and Kajima.

4.4 Proposed Countermeasure

The proposed countermeasures were divided into two phases consist of; 1)

Structural Steel Fabrication Accreditation, 2) Checklist for Fabricated Steelwork

4.4.1 Structural Steel Fabrication Accreditation

Structural steel fabrication accreditation scheme by Singapore Structural Steel

Society state the accreditation for the fabricator, which will ensure that the structural

steelwork construction is carried out by suitably qualified fabricators. Quality control

of the steel work is possibly another issue in Thailand, as show in the research that the

welding work was done poorly in many steel structures. The countermeasure against

this issue is to establish the accreditation of fabricators and welders to control the

quality of the steel work. Additionally, the accreditation shall divide into several levels

or types, to indicate the work that a certain fabricator could do. For example, the

structural steel fabricators accreditation of Singapore was divided into three categories,

as Category S1 to Category S3 based on their capabilities, track records, financial

status, technical capability and the standard of the fabrication plants. infrastructure,

resources and capabilities to fabricate and erect structural steel structures of that

companies. For example, the fabricator that has building of over 30 m in height, or large

span bridges of over 30 m will be classified as Category S1, or up to 30 m will be

classified as Category S2, and finally up to 10 m will be classified as Category S3.

Ref. code: 25615922040299ZBX

57

Table 4.14 Guidelines of Classification of Thai steel constructors.

Ref. code: 25615922040299ZBX

58

Table 4.15 Equipment of guidelines of classification of Thai steel constructors.

4.4.2 Checklist for Fabricated Steelwork

A checklist given in the Table 4.14 can be used as a guide to assess compliance

of the fabricated steelwork. The checklist provides references to the international

standards and defines documentation required to claim compliance. Depending on the

outcome of the assessment, the fabricated steelwork may be subject to additional NDT

and (destructive) testing. There are additional considerations if steel is supplied to a

non-Thailand material supply standard. Inspector have a task of verifying compliance

of the steel work that fabricated from foreign countries. It is the responsibility to make

sure that the fabricator complies with applicable international standards and rules.

Therefore, evaluation of compliance of fabricated steelwork poses some significant

risks. In order to achieve compliance, it may be necessarily to provide a full third-party

supervision and inspection to the overseas fabricator. The quantity of NDT and

inspection may need to be significantly higher than that recommended in standard to

verify compliance. An important aspect for the safety of welded connections is the

acceptance level of external and internal weld imperfections defined in standard.

Therefore, welding procedures and welder qualification tests performed to overseas

standards usually need to be re-qualified due to the difference in the acceptance levels

for weld imperfections.

Ref. code: 25615922040299ZBX

59

4.4.2.1 Material Selection

This study sets out of minimum requirements for the selection of materials of the

construction of steel structures. All structural steel coming within the scope of these clauses

shall, before fabrication, comply with the requirements such as Thai Industrial Standards,

Australian or Joint Australian/New Zealand Standards, British Standards, Japanese Standards

and American Standards.

4.4.2.2 Fabrication

A manufacturer’s certificate of compliance with the specified material in 4.3.2.1 can

requested, but the request is usually contained in the contract documents rather than

introduced during fabrication as follows;

• Identification The steel grade shall be identifiable at all stages of fabrication and any

marking of steelwork shall be such as to not damage the material.

• Fabrication procedures such as Straightening, curving and cambering, cutting, drilling,

Precamber, Holing, Tolerances, and etc.

4.4.2.3 Welding

Welded connections may be made by butt, fillet, plug or slot welds by welded joints

are to be welded in accordance with AWS. The welding procedure, weld preparation, the

welding consumables and the welding parameters, shall be qualified before welding of either

the structure or the component commences. The fabricator shall be welding procedure and list

the applicable parameters in the welding procedure qualification record (also known as PQR),

which welding procedure specification (WPS) is sample of welding before welded, which is

the formal written document provides direction to the welder or welding operators for making

quality production welds. WPS is supported by PQR.

4.4.2.4 Welding Inspection

The inspector shall conduct a VT in accordance with the requirements of DPT 1561.

Inspection and measuring shall be sufficient to enable the inspector to detect imperfections

that could occur on welds or test pieces. Prior to and during or after welding, the inspector

shall inspect the set-up of the work and ensure that

1. Welds are in accordance with the drawings.

2. The welding is carried out on the specified material with suitable equipment.

3. Correct procedures are maintained and the work is performed in accordance with

requirements standard.

Ref. code: 25615922040299ZBX

60

All welds shall receive a full VT in accordance with criteria of welding defect. Welds

shall be inspected in accordance to DPT 1561 to 1565 and, where appropriate, DPT 1561 to

1565. Inspection for the relevant types of imperfections shown in Table 2.1 shall be carried

out in accordance with relevant standard, as appropriate. Repaired welds shall be respected to

the same level as that original specified or inspection and testing plan (ITP). Reporting is too

necessary in welding inspection, test reports for non-destructive examination (NDT) shall

comply with the suitable standard and shall include the following information by identity of

testing personnel and statement on whether the weld complies with the requirement of this

section. If the weld does not comply, the location and extent of the defect are given and should

have results of re-tests.

4.4.2.5 Coating

Before coating shall be surface preparation and application of coating systems shall

be in according to ISO 8501 (SA2.0 and SA2.5). coating inspection recommendations are

covered in detail in ISO 4628 for corrosion defect and ISO 19804 for coating thickness.

Standards of workmanship for each step in the system, surface preparation, suitability of

equipment, drying and curing time intervals between coats and handling, coating thickness,

and reporting.

4.4.2.6 Erection

During the erection of a structure, steelwork shall be made safe against erection

loading including loading by erection equipment or its operation, and wind. And erection

procedures, the requirements specified in fabrication procedure shall also be observed during

the erection of the steel frame and during any modifications to the steelwork in the course of

erection such as Full contact splices, Welding, Holing, and Bolting. Delivery, storage, and

handling also important because all work shall be protected from damage in transit. And

adequately protect all surfaces prepared for full contact splices, all bolts, nuts, washers,

screws, plates and articles generally shall be suitably packed and identified.

Assembly and alignment, all matching holes shall align with each other so that so that a gauge

or drift, equal in diameter to that of the bolts, shall pass freely through the assembled contact

faces at right angles to them. For bolt, the length of a bolt shall be including all bolts, at least

one clear thread shall show above the nut after tightening. And welding shall not have all type

of defect such as porosity, undercut and cracking.

Ref. code: 25615922040299ZBX

61

Table 4.16 Checklist for inspection fabricated steel structure

No. Detail Note Document

1. Materials

1.1 Do all construction materials

comply with standard specified and

records available? And is there

evidence of conformity with the

material supply standard?

Material test

certificates

1.2 Has a metallurgist or a materials

engineer confirmed that the

material supplied to an alternate

internationally recognized standard

is equivalent to a material standard

referenced from TISI?

Material test

certificates

1.3 Has a metallurgist or a materials

engineer confirmed that the

material supplied to an alternate

internationally recognized standard

is equivalent to a material standard

referred to TISI?

Record of approval by

the design engineer

1.4 If the material to be replaced is

certified as equivalent to the

standard. Are the tolerances and

uniformity of the mechanical

properties (COV ≤ 10%) of the

materials supplied are in

accordance with the TISI standard?

Record of approval by

the design engineer

1.5 Has the material been supplied with

test reports or test certificates

prepared by a laboratory accredited

by signatories to the International

Laboratory Accreditation

Cooperation (ILAC) Mutual

Recognition Agreement (MRA) on

behalf of the manufacturer?

Test certificates

1.6 Are construction materials traceable

through the entire fabrication and

construction process?

As-built fabrication

drawings, traceability

record

Ref. code: 25615922040299ZBX

62

Table 4.16 Checklist for inspection fabricated steel structure (Continue)


2. Fabrication Practice

2.1 Does the fabricator have

procedures/records to ensure that

the following operations

complies with client’s

specification and/or requirements

of customer

2.1A Tolerances Production Quality Plan

2.1B Transition of thickness and width

for seismic members

Production Quality Plan

2.1C Holing Production Quality Plan

2.1D Straightening, curving and

cambering

Production Quality Plan

2.1E Tolerances Production Quality Plan

2.2 Have all stages of construction

(including welding) been

adequately reviewed by a person

who is competent to undertake

the review?

Record of review by

construction reviewer

2.3 Does the fabricator maintain

procedures to ensure work is

within fabrication tolerances?

Does the fabricator maintain

dimensional check lists and

reports as identified in the

Quality Plan?

Dimensional inspection

checklist reports

Ref. code: 25615922040299ZBX

63



3. Welding

3.1 Has welding been specified in

accordance with standard as

applicable?

Project documentation

3.2 Have matters for resolution been

resolved/addressed prior to

welding and evidence exist?

Technical review

checklist

3.3 Has fabricator qualified welding

procedures prior to welding?

Approval records

required or third-party

inspection reports

3.4 Have welders been suitably

qualified to carry out tasks

according to welding procedure?

Welder/welding operator

qualification certificate

3.5 Do all construction materials to

be welded comply with the

materials listed in the standard

and evidence exist?

Material test certificates

Record design engineer’s

approval

3.6 If the answer to the above is

“not”, has the weldability of

alternative steel grade been

established and evidence exist?

PQR/WPS Qualification

test reports

3.7 Have welding consumables been

selected in accordance with the

(seismic requirements of)

standard?

Welding consumables

test certificates

3.8 Have welding consumables been

used within the welding

parameter ranges specified by

the manufacturer and the

standard?

Welding inspection

reports confirming the

suitability of WPS or

records of review

3.9 Have welding procedures been

approved prior to welding by the

design Engineer and evidence

exist?

Records or review and

approval prior to

welding.

Ref. code: 25615922040299ZBX

64



3. Welding

3.1 Is there evidence (e.g. inspection

reports) that welding complied

with all the appropriate

requirements of standard such as

workmanship, quality of welds

and dimensional tolerances?

Welding coordination

personnel qualification

records

3.11 Is there evidence that fabricator

complied with a quality

management system such as ISO

9001?

Certified ISO 9001

4. Welding Inspection

4.1 Has the extent of non-

destructive examination been

nominated/approved by the

design engineer?


4.2 Has inspection been carried out

in accordance with the standard?

Inspection reports

4.3 Has welding inspection

personnel been properly

qualified and evidence exist?

Welding inspection

personnel qualification

records

4.4 Has non-destructive

examination personnel been

properly qualified and evidence

exist?

NDT personnel

qualification records

4.5 Do final inspection reports exist

stating that inspected welds

comply with the permissible

level of imperfections of weld as

applicable?

Final inspection report

Ref. code: 25615922040299ZBX

65



5. Coating

5.1 Has steel surfaces been prepared

in accordance with the

requirements of standard for

coating system?


5.2 Has the coating system been

applied in accordance with the

requirements of standard for

coating system?


5.3 Has inspection of protective

coatings been carried out in

accordance with the

recommendations?

Inspection reports

5.4 Has structural steel members been

adequately protected from coating

damage during handling and

transport?


5.5 Has the coating system damage

by welding, erection or other

causes been adequately repaired?


Ref. code: 25615922040299ZBX

66

Chapter 5

Conclusion

5.1 Conclusion

In this study, the defect or damage on the fabricated steelwork in Thailand. It

was found that, most of fabrication defects are found in welded. They are undercut,

overlap and porosity. Distortions due to fabrication process are also observed.

Thickness of coating is insufficient. Assembly defects are found such as improper bolts

installation, caused from poor workmanship in the construction process. These defects

can be fixed directly by redoing the construction process, such as re-weld, re-coat, and

re-install. The defect from poorly coated steel could cause a severe damage to the

structure, corrosion damage on the steel surface. In order to guarantee the safety and

serviceability of steel structures in Thailand, the Thai authorities or the third party

should strictly check the quality of steel structures.

Finally, the implementation of a fabricator accreditation in conjunction with

checklist for inspection the quality of fabricated steel structures. These two

countermeasures are essential to ensure high quality and establish standard for steel

construction in Thailand. Internationally there has been various structural steel quality

initiatives to reduce the compliance risk to all parties associated with fabrication of

structural steel. In addition, this paper aim of empowering Construction Reviewers to

more competent and fulfill their role in controlling quality, for projects featuring

structural steel.

5.2 Suggestion of Solutions

5.2.1 Fabricators Accreditation

The structural steel fabricators accreditation scheme is also important. The

Structural Steel Fabricators Accreditation Scheme will grade steel fabricators for

consist of track records, financial status, Skilled technical, human resource and the

standard of the fabrication plants. There will be three categories of fabricators

accreditation by Table 4.14 to 4.16 are Guidelines of Classification of Thai steel

constructors.as follows:

1. Category S1: Large Company

2. Category S2: Medium Company

3. Category S3: Small Company

Ref. code: 25615922040299ZBX

67

5.2.2 Checklist for Inspection the Quality of Fabricated Steel Structures

Thailand needs to have a system in place to ensure quality of steel structures for

inspect the steel structure practically by using this system. So, we should have proposed

guideline to provides official with a tool to ensure quality and public safety involved

steel structures.

The checklist will include six main items as follows:

1. Material selection

2. Fabrication

3. Welding

4. Welding Inspection

5. Coating

6. Erection

Ref. code: 25615922040299ZBX

68

References

AWS D1.1/D1.1M. Structural Welding Code – Steel. American Welding Society,

Miami, FL 33126, 2010.

Baughurst, L., Voznaks, G. (2009). Welding defects, causes and corrosion. Australian

Bulk Handling Review: July/August 2009, 26-28.

DPT 1561 – 51. Structural Steel welding inspection standard. Department of Public

Works and Town & Country Palnning, Thailand, 2008.

ISO 4628 – 1. Paints and Varnishes – Evaluation of degree of coatings –designation of

quantity and size of defect, and of intensity of uniform changes in appearance –

Part 1: General introduction and designation system. International Standard

Organization, Switzerland, 2003.



Part 2: Assessment of degree of blistering. International Standard Organization,

Switzerland, 2003.



Part 3: Assessment of degree of rusting. International Standard Organization,

Switzerland, 2003.



Part 4: Assessment of degree of cracking. International Standard Organization,

Switzerland, 2003.



Part 5: Assessment of degree of flaking. International Standard Organization,

Switzerland, 2003.

JASS 6. Japanese Architectural Standard Specification JASS 6 (1993) Structural

Steelwork Specification for Building Construction. Architectural Institute of

Japan, Japan, 1993.

Ref. code: 25615922040299ZBX

69

JIS B 1186. Set of high strength hexagon bolt, hexagon nut and plain washers for

friction grip joints. Japanese Industrial Standard, Japan, 1995.

RCSC. Specification for Structural Joints Using High – Strength Bolts. Research

Council in Structural Connections, Chicago, Illinois, 2009.

Structural Steel Fabricators Accreditation Scheme. Singapore Structural Steel Society

(SSSS), Singapore, 13 Mar, 2016.

ISO 19840 Paints and varnishes -- Corrosion protection of steel structures by protective

paint systems -- Measurement of, and acceptance criteria for, the thickness of

dry films on rough surfaces, 2012.

International Standard Organization. ISO 8501-1 – Rust grades and preparation of

uncoated steel substrates and steel substrates after overall removal of previous

coatings, 2007.

MBMA: Metal Building Manufacturers Association, Metal Building Systems Manual,

2016.

ASTM E797 Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse

Echo Contact Method, 2015.

Fussell, A., Cowie, K., Hicks S., Karpenko, M.,. Ensuring Compliance of Structural

Steelwork - Regardless of Origin. Steel Advisor QLT1001, Steel Construction

New Zealand, 2016.

Fontana, M. (Ed). (1986). Corrosion Engineering. New York: McGraw-Hill.

Ref. code: 25615922040299ZBX

70

Appendices

Ref. code: 25615922040299ZBX

71

Appendix A

Reference Photo for Paint Inspection

Fig. A-1 Blistering of size no.2

(Reference: ISO 4628-2:2003, Page 3. Figure 1)

Ref. code: 25615922040299ZBX

72

Fig. A-2 Blisters of size no. 3


Ref. code: 25615922040299ZBX

73

Fig. A-3 Blisters of size no. 4


Ref. code: 25615922040299ZBX

74

Fig. A-4 Blisters of size no.5


Ref. code: 25615922040299ZBX

75

Fig. A-5 Degree of rusting Ri 1

(Reference: ISO 4628-3:2003, Page 4, Figure 1)

Fig. A-6 Degree of rusting Ri grade 2


Ref. code: 25615922040299ZBX

76





Ref. code: 25615922040299ZBX

77



Ref. code: 25615922040299ZBX

78

Fig. A-10 Cracking without preferential direction


Ref. code: 25615922040299ZBX

79

Fig. A-11 Cracking with preferential direction


Ref. code: 25615922040299ZBX

80

Fig. A-12 Flaking without preferential direction


Ref. code: 25615922040299ZBX

81

Fig. A-13 Flaking with preferential direction


Ref. code: 25615922040299ZBX

problems and countermeasures of the quality of …

Documents