BIỆN PHÁP HÀN ỐNG KIM LOẠI

PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
-----------------------------------------------------------------------------------------------------------------------------------

METHOD STATEMENT
FOR MVAC WELDING

Prepare by :

SUB CONTRACTOR
NAME: Hong Soon
Min
DATE : 08-April-2015

Submission Ref. :PSC-HK-MS-M-0004
Checked by :
Approved by :

POSCO
NAME:

POSCO
NAME:

NAME:

DATE :

DATE :

DATE :

Date: 08-April-15
Revision: Rev00

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Consulted by:

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HKL


PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------Table of Contents

1.INTRODUCTION.......................................................................................................................................3
1.1 Purpose ...................................................................................................................................................3
1.2 Scope ......................................................................................................................................................3
1.3 Exclusions ...............................................................................................................................................3
2.

GENERAL
.................................................................................................................................................3
2.1

Program....................................................................................................................................................3
2.2 Location Address..................................................................................................................................3
2.3
Approvals................................................................................................................................................3
2.4 Labor resources......................................................................................................................................4
2.5 Communications ...................................................................................................................................4
2.6 Site Resources Required........................................................................................................................4
2.7 Temporary material.................................................................................................................................4
2.8
Protection................................................................................................................................................4
2.9
Equipment/Tools....................................................................................................................................5
2.10 Hot works.............................................................................................................................................6
2.11 Confined space works.........................................................................................................................6
2.12 Emergency & Safety Equipment.........................................................................................................6
2.13 Materials required for installation..........................................................................................................8
2.14 Schedule of drawings..........................................................................................................................9
2.15 Schedule of inspection........................................................................................................................9
2.16
Attendees............................................................................................................................................9
2.17 Safety Briefing.....................................................................................................................................9
2.18 Mitigation of Risk.................................................................................................................................10

3. Actual Works Method Statement..........................................................................................................................10
3.1 Delivery and Store.................................................................................................................................10
3.2
Welding
...............................................................................................................................10
3.2.1
Drying welding rods.........................................................................................................................10

3.2.2
Marking pipes...................................................................................................................................11
3.2.3 Ventilation ......................................................................................................................................................11
3.2.4
Methodology...................................................................................................................................12
3.2.5
Welding guide...................................................................................................................................13
3.3 Setting to work.......................................................................................................................................61
3.4 Testing..................................................................................................................................................61
3.5 T&C Register........................................................................................................................................62
3.6 Reports................................................................................................................................................62
4.

Appendix..................................................................................................................................................64

4.1

Certificate of calibration ........................................................................................................................64
4.2 Instrument catalogue and manual.................................................................................................70
4.3 Certificate of welders. …………………..............................................................................................................71

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015

----------------------------------------------------------------------------------------------------------------------------------1. INTRODUCTION
1.1 Purpose
The purpose of this Method statement is to bring the requirements from the technical specifications, drawings
together in one convenient document for reference by the drafters, factory, site installers, QA/QC and all parties who
are concerned with the project. And this methodology to be followed for the welding of the chilled water piping,
condenser water piping and fitting into the high or low level and the inspection.

1.2 Scope
This is applicable to the welding of all chilled water pipes, condener water pipes as set out in the project technical
brief and the approved drawing.

1.3 Exclusions
Not application.

2. GENERAL
2.1 Program
2.1.1 Ensure that the shop drawing used for the references at site is approved for construction.
2.1.2 Ensure that designated manpower to conduct works at site must be properly trained and well oriented by the
safety engineer.
2.1.3 All equipments, tools and mobile scaffolding to be used must be inspected and approved by authorized safety
engineer at site.
2.1.4 All staffs associated with the works shall be sufficiently experienced.
2.1.5 When the workers climb up the working platform, ladder, his hands must be free.
2.1.6 All materials to be used at site must be properly secured and clean.
2.1.7 Working period to base on civil work and piping installation schedule which will be attached after getting
approval (Waiting for approval).

2.2 LOCATION – ADDRESS
Application for Basement 3 and all high floors.

2.3 APPROVALS
Materials of submission (Waiting for submission & approval).
Shop drawing (Waiting for submission & approval).

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------2.4 LABOR RESOURCES

The pipe team will coordinate and carry out as below organization chart:

2.5 Communications
Office mobile phone or walkie-talkie will be used during working time.
2.6 SITE RESOURCES REQUIRED
Temporary fire protection equipment.
Site electric panel should be needed as site condition.
2.7 TEMPORARY MATERIALS
Materials cover needs to be prepared on the floor and cover pipe when needed.

2.8 PROTECTION
Materials cover needs to be prepared on the floor and cover pipe when needed.

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------2.9 EQUIPMENT/TOOLS

Ensure the availability of equipment and tools provision for AC Piping welding works as follows:

1. Welding
clothes/gloves

2. Wire Brush

3. Silver ink marker pen

4. Welding dryer

5. Grinder

6. Clean rug and
cloth

7. Protective Glasses

8. Electric Arc
machine

9. Hammer

10. Lighting

11. Fire Extinguiser

12. Caution Tape

13. Welding rod

14. Scaffolding

15. Fire blanket

16. Level measure

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------2.10 HOT WORKS
Hot works comprise of the welding and will be carried in accordance with hanger, support weld instruction manual.
The hot welding will be under tolerance clean workshop environment to ensure no risk of dirt contamination .
Where such exothermic wielding works are in progress, fire extinguishers shall be provided at full times. When
such exothermic welding is carried out, the workers shall be provided with welding gloves. Hot works proposed for

on site. The place to be proposed at basement floor.

2.11 CONFINED SPACE WORKS
Not application.

2.12 EMERGENCY & SAFETY EQUIPMENT
1) Safety helmet

2) Safety shoes

3) Safety uniform

4) Hand gloves

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
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5) Safety goggles

6) Fire extinguisher

7) Welding mask

2.13 MATERIALS REQUIRED FOR WELDING
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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------GI pipe & black steel pipe, fitting as elbow, tee, reducer, flang, bracket, welding rod.

1. Black steel (BS)
pipe

2. GI pipe

3. BS fitting

4. GI fitting

5. Flange

6. C-channel

7. Welding rod

2.14 SCHEDULE OF DRAWINGS
Refer to shop drawing layout of floors as below:

2.15 SCHEDULE OF INSPECTION
Refer to ITP form as the attached file in below.
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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------2.16 ATTENDEES

2.16.1 Sub-contractor manager.
2.16.2 Sub-contractor site manager.
2.16.3 Main contractor MEP coordinator.
2.16.4 Main contractor mechanical engineer.
2.16.5 HKL M&E manager.

2.17 SAFETY BRIEFING
2.17.1 Safety shall be in first priority during construction, safety staff shall be present on site all the time to
supervise and to remind workers to observe safety requirement. Stop work order shall enforce once its dose not
meet the safety requirements.
2.17.2 Safety shall conform strictly observed. All workers and staff on site shall be oriented of safety requirements.
All safety equipment such as cloths , shoes, helmet , gloves , safety belt should provide and regularly checked
during construction.
2.17.3 The engineer shall inspect all subcontractor tools prior to be used on site.
2.17.4 Safety Supervisor shall be present for all the safety site inspection.
2.17.5 For the safety of worker, grounding wire for the electric ARC process must be provided and wet cloths,

protective glasses, long sleeve cloth must be imposed to worker.
2.17.6 Fire extinguisher shall be provided at welding area and safety provision must done to ensure usage
workability.

2.17.7 Safety working with Scaffolding
2.17.7-1 All scaffolds must be erected under the supervision of a competent and experienced person- usually the
construction superintendent. This includes moving scaffolds from one position to another. Each leg of a scaffold
must be supported by and adequate footing. Loose bards, bricks and other material do not provide a safe, adequate
base.
2.17.7-2 Where the working platform in more than 10 feet off the ground, the scaffold shall have guardrails
installed.
2.17.7-3 If people are working under the scaffold, toe boards must be used to prevent tools and materials from
falling on them.
2.17.7-4 Workers are not to climb the metal tubular frame of the scaffold to get the working platform. Other, safer
means of access must be used – a ladder or access from the building.
2.17.8 Safety working with Mobile Scaffold

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
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2.17.9 Mobile scaffolds have restricted reach unless a guy wire secures them. They are more susceptible to

overturning and require a smooth, level working surface. A complete guardrail system must be used at elevations
above 10 feet and shall be used at all working levels. Scaffold should be moved when unoccupied and only by
pushing from the base. Wheel brakes must be set when scaffold is in use.

2.18 MITIGATION OF RISK
Impact damage during pouring of concrete installation to be monitored constancy white concrete is poured.
Correct connections or materials, ensure the final installation and connections are inspected and signed off with
photographic records by MEP coordinator on site M&E staff from contractor, architect and client.

3. ACTUAL WORKS METHOD STATEMENT
3.1 DELIVERY AND STORE
Materials arrived to site shall be inspected and stored according to manufacturer recommendations. Materials shall
be stored in the covered and dry space. During the receiving materials of pipe & fitting, manpower shall be used to
make piping system. The pipe and accessories shall be protected and covered with polythene sheets before
installation and welding.

3.2. Welding
3.2.1 Drying welding rods
All welding rods shall be dried by the equipment shown below:

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.2 Marking pipes

All butt welds shall be marked as shown below:

All butt welds marked shall be registered onto a from sowing welder’s name, pipe diameter,
welding date ,welder name, inspection pass/fail.
The form shall be submitted for approval separately under ITP for Welding.
3.2.3 Ventilation

In tight areas especially in Basements, fans shall be installed with flexible houses for
extracting welding fumes to the outside area to improve health and safety.

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.4 Methodology
1.

Get the desired approved pipe size and materials to be used and make making based on approved
plans.

2.

No welding will be permitted on any galvanized after manufacture.

3.

Pipe surface. (100mm from welding point) shall be free from oils, dirt and dust and dried well pried
well prior to welding connection.

4.

When cutting pipe ,make sure to use circular edge for making and cut squarely accordingly.

5.

Bevel all circular surface of pipe prior to weld connection by grinder – Refer to Table 2 for bevel
angles.

6.

Fit-up with three side spot welding and check allowable gap (Refer to enclosed sheet), check pipe
alignment and bevel prior to full welding.

7.

After welding (First passed) removed all welding flux by wire brush and grinder.

8.

Full welded (Second passed) pipe connection shall be cleaned with steel brush and touch paint with
upon completion, all welded joints shall be thoroughly cleaned off with a stiff wire brush and , after
inspection, painted with a coat of zinc phosphate anti-corrosion paint.

9.

Welders identification must be inspected by visibly mark adjacent to welded connection prior to
inspection and painting.

10. All welded pipe must be inspected by visual check and approved by their company’s respective
QA/QC engineer.
11. Where welding is carried out in the proximity of inflammable material, the contractor shall take
special precautions to protect the building fabric from the risk of fire.
12. All welds shall be reinforced on the external surfaces run off smoothly at ends with no undercutting.
13. Where an oxy-acetylene flame is used for cutting, the flame shall be used by a qualified operative,
care being taken to avoid damage to the metallic structure of the tube.
14. All welded branches shall be formed by burning into the main run welding on specially prepared
prepared branch shoes which must be the correct size for the diameter of the pipe. In each case, the
position of the hole must be carefully marked out with a scriber using the appropriate branch shoe,
and the edges at floor level in the “hand down” position .
15. The following table shows the largest permitted.
Branch
40 mm
50
65
80
100
125

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Main
65mm
80
100

125
150
200

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
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16. The distance between the centers of two adjacent welds shall not be less than twice the diameter of
the largest branch.
17. Reinforce piping at all anchor points as shown on the drawing details.
18. Cap openings in pipes during progress of the work to prevent ingress of dirt and foreign bodies in to
the installation.
19. For pipe leakage test, standard, resting procedure and document shall be done accordingly.

3.2.5 Welding guide
3.2.5.1 Welding with coated electrodes (SMAW)
The main welding process used to install the pipelines is manual welding with coated electrode. It will be
completed at workshop located at basement floor for main welding work.

Details of proposed welders and certificate of them is shown as below.

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.2 Welding joint details

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.3 Welding joint process

1.

Measure the size of pipe and clean the surface of pipe, Surface shall be free from oils, dirt and
dust and dry well (100mm from welding point).

2.

Check the bevel in accordance with pipe thickness. If bevel is not correct, it shall be revised by grinder.

3.

Adjust pipe so that centre is on line.

4.

All welding of pipe shall be made by the electric arc process. Electrodes shall be selected in
accordance with approval by the Mechanical Engineer.

5.

Spot welding for pipe size 300A and below shall be done at 3 points, for pipe size 350A-500A shall be
done at 6 points ant for pipe size 550A and above shall be done at 8 points.

6.

For flange welding, sport welding shall be at 1 point and flange surface shall be right angle to pipe
axis. Then spot welding shall be done at 3-4 points prior to weld officially. Seam of welding in outside
face shall not be out flange face.

7.

Roll pipe to continue from up and down. For fixed pipe, weld well be carried out from down to up.

8.

After welding, all welded areas shall be cleaned by wire brush and grinder.

9.

Welding point must be free from rust.

10. All pipe welded must be inspected by visual check. The width of the completed weld shall extend no
more than 3.2 mm wider that the original grove. Any defects found shall be reported to the respective
Engineer for his inspection and instruction. No repairs to the weld shall be allowed and the pipe
extending 250mm either site of the detective weld shall be cut square and true and the welding process
above shall be implemented for jointing the pipe again.

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.4 Electrode positioning angles

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.5 Pipe classification

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.6 ASME/EN position

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
----------------------------------------------------------------------------------------------------------------------------------3.2.5.7 Pipe welding in vertical down (Downhill)

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PROJECT: EXCHANGE SQUARE (STREET 106 SITE)
TITLE OF WORK: METHOD STATEMENT MVAC
FOR WELDING
08. APRIL. 2015
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