MOS, Method of Statement of Weldinng, Biện pháp hàn ống, Cách hàn ống trong hệ thống của Tòa nhà cao tầng, nhà máy, văn phòng cao ốc có sử dụng đường ống vật liệu kim loại, bao gồm ống vật liệt bằng sắt, đồng, thép không rỉ
Purpose
This Method Statement consolidates the technical specifications and drawings into a single, accessible document for reference by drafters, factory personnel, site installers, QA/QC teams, and all stakeholders involved in the project It outlines the methodology for welding chilled water piping, condenser water piping, and fittings, addressing both high and low-level installations, along with the necessary inspection procedures.
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.
Exclusions
GENERAL
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).
Location - Address
Application for Basement 3 and all high floors.
Approvals
Materials of submission (Waiting for submission & approval).
Shop drawing (Waiting for submission & approval).
Labor resources
The pipe team will coordinate and carry out as below organization chart:
Communications
Office mobile phone or walkie-talkie will be used during working time.
Site Resources Required
Site electric panel should be needed as site condition.
Temporary material
Materials cover needs to be prepared on the floor and cover pipe when needed.
Protection
Materials cover needs to be prepared on the floor and cover pipe when needed.
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
Hot works
Hot works, including welding, will be conducted following the hanger and support weld instruction manual in a clean workshop environment to prevent dirt contamination Fire extinguishers will be readily available during exothermic welding operations, and workers will be equipped with welding gloves for safety The proposed location for these hot works is the basement floor.
Confined space works
Emergency & Safety Equipment
GI pipe & black steel pipe, fitting as elbow, tee, reducer, flang, bracket, welding rod.
1 Black steel (BS) pipe 2 GI pipe
Refer to shop drawing layout of floors as below:
Refer to ITP form as the attached file in below.
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.
All scaffolds must be erected under the supervision of a qualified and experienced individual, typically the construction superintendent This supervision extends to the relocation of scaffolds It is essential that each leg of the scaffold is supported by a stable and adequate footing, as loose boards, bricks, and other materials do not create a safe 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.
Workers must avoid climbing the metal tubular frame of the scaffold to access the working platform Instead, they should utilize safer alternatives such as a ladder or access from the building.
2.17.8 Safety working with Mobile Scaffold
Schedule of drawings
Refer to shop drawing layout of floors as below:
Schedule of inspection
Refer to ITP form as the attached file in below.
Attendees
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.
All scaffolds must be erected under the supervision of a qualified and experienced individual, typically the construction superintendent This supervision extends to the relocation of scaffolds It is essential that each leg of the scaffold is supported by a stable footing, as loose boards, bricks, and other materials do not create a safe and 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.
Workers must avoid climbing the metal tubular frame of the scaffold to access the working platform Instead, they should utilize safer alternatives such as a ladder or access from the building.
2.17.8 Safety working with Mobile Scaffold
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.
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.
Actual Works Method Statement
Delivery and Store
Upon arrival at the site, materials must be inspected and stored in accordance with the manufacturer's guidelines It is essential to keep materials in a covered and dry area When receiving pipes and fittings, labor should be utilized to assemble the piping system Additionally, pipes and accessories should be safeguarded and covered with polythene sheets prior to installation and welding.
Welding
All welding rods shall be dried by the equipment shown below:
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.
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.
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.
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.
3.2.5.1 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
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.
3.2.5.7 Pipe welding in vertical down (Downhill)
3.2.5.8 Pipe welding in vertical up (Uphill)
3.2.5.10 Metal inert gas welding (GTAW/GMAW)
3.2.5.10.1 Gas tungsten arc welding (GTAW)
3.2.5.10.2 Gas metal arc welding (GMAW)
Setting to work
Testing
T&C Register
Reports
Appendix
Certificate of calibration
Waiting for pressure gauge calibration The meantime, we may use brand new pressure gauge Calibration certificate will be submiited later.
Instrument catalogue and manual
BX1-180B Input Voltage (V): 230/400 Non-load Voltage (V): 48 Current range (A): 60-180 Rated Duty Cycle (%): 180A@10%, 75A@60%
Input Capacity (KW): 7 Class of insulation: H Applied Welding Rod (mm): 2.5-4.0 Fuse (A): 20
BX1-200B Input Voltage (V): 230/400 Non-load Voltage (V): 48 Current range (A): 60-200 Rated Duty Cycle (%): 200A@10%, 82A@60%
Input Capacity (KW): 7.5 Class of insulation: H Applied Welding Rod (mm): 2.5-4.0
Certificate of welders
The qualified welders listed possess certification for welding pipes ranging from DN65 to DN750 Prior to commencing actual welding work on-site, they will demonstrate their skills by welding a sample short pipe, which will be submitted to the main contractor and HKL engineer for inspection and approval.