The purpose of this HVAC mechanical method statement is to outline the methodology to be implemented for chilled water CHW piping system activities and to ensure that all works are carried out in accordance with the approved construction drawings, project specifications and manufacturer installation instructions.
Mechanical method statement covers above ground chilled water piping system that shall be installed in accordance with the contract scope of work.
The work will be carried out as per approved planning sequence of work and project schedule with adequate resources to meet the contract targets.
Construction methodology contains the construction procedures, the requirements of materials, manpower, equipment and management thereof.
This Method Statement covers all chilled water piping system installation activities that may include:
a) Chilled water piping (Supply/Return)
b) Valves, Fittings, Accessories
c) Pressure Testing
- Project Specifications
- Tender/ Contract documents
- Project IFC Drawings
- Approved Shop Drawing
- Project Quality Plan
- Project HSE Plan
Roles and Responsibilities
All personnel engaged in the installation of Chilled water Piping System activity shall be having adequate experience in their respective discipline.
Construction Manager is responsible for the overall works.
Site Engineer, Surveyor and Foreman is responsible for the installation activities in accordance with the scope of work, approved drawings, related specification and HSE requirements implementation.
QA/QC Engineer shall ensure that all works are carried out strictly in accordance with approved method statement, and inspection & testing plan.
Safety Engineer, Safety Officer, Safety Assistant shall ensure that works are carried out in accordance to approved method statement, Risk assessment and control measures.
Engineering department shall ensure that the shop drawings issued to site are approved and latest, the shop drawings shall follow the IFC drawings, project specification requirements and local authorities codes and regulations.
Material Storage and Handling
In this activity following materials shall be used/required:
Chilled water CHW pipes & fittings (pipes & fittings)
Valves, strainer, air vent and accessories
Support (Threaded rod, clamps, nuts/bolts, jutes, Teflon tapes etc.)
Material will be delivered at site in undamaged condition, in manufacturer’s packaging, with identifying labels intact and legible.
All related documents i.e. delivery notes, country of origin, bill of landing and test certificates shall be available along with materials.
Materials will be off loaded according to manufacturer’s recommendations.
Pipes or fittings will not be dropped or dragged.
Pipes and fittings will be offloaded in suitable lay down area prior to transport to site.
The storage area must be flat, ground must not be marshy or unstable and it must not contain any corrosive material.
Timber supports of suitable size shall be placed at equal distance below the Chilled water pipes.
Pipes shall be stacked on a flat surface free from any sharp objects and shall be given adequate supports at all times.
While stacking it shall be ensured that pipes of bigger sizes will be placed at the bottom and smaller sizes at the top.
Pipes shall be protected from direct sunlight as per manufacturer’s recommendation, where ever applicable.
While handling the pipes care shall be taken as per manufacturer recommendations to avoid damage to pipe coating.
End caps will not be removed from all pipes until taken out for installation.
Delivery of chilled water pipes and fittings will be checked / Inspected by QC engineer to ensure all items on the delivery note are correct prior to signing. Any shortage or damaged items should be recorded on the delivery note and damaged materials will be stored separate with identification tag or shall be removed from site.
Upon delivery of materials at contractor’s site stores, inspection will be offered for client approval.
Plant & Equipment’s
- Pipe Cutter
- Paint brush
- Measuring Tape, Plum bob, chalk line, Nylon string line.
- Ball peen hammer
- Spirit Level
- Pipe fitter standard tool box
- Socket spanner
- Screw driver
- Test Plugs, end caps
- Water level
- Square drive Ratchet spanner
- Box spanner
- Allen socket adaptor
- Calibrated torque wrenches
- Electric impact screw driver
General Requirements for Chilled Water Pipe Installation
a) Ensure that the chilled water pipes, fittings, valves and accessories are correct and as per project specification and approved material submittals before commencing the site installation works.
b) Prior to commencing any works, a risk assessment must be conducted, taking into account all possible risks and the appropriate precautions put in place, i.e. fire extinguishers, fire blankets, safety harnesses, etc. Refer to the risk assessment/risk management section of this method statement.
c) Ensure that shop drawing used on site are approved and latest prior to commencing works on site.
Manufacturer’s recommendations are to be obtained from one of the listed vendors in the project specifications/material submittal.
All workers to attend safety induction training on the safe installation methods by the safety department.
Ensure that pipe & fittings materials received are inspected; found acceptable as per approved materials submittal.
Ensure that all related materials are of approved make and all accessories are available before carrying out any work.
Prior to commencement of work, inspect areas and access to confirm that the site is ready to commence the chilled water piping work.
All relevant documentation (drawings) and materials applicable to particular section of works will be checked by site engineer prior to commencement of work and ensure that shop drawings are as of latest revision approved.
The site engineer/ site supervisor will give necessary instructions to tradesmen (pipefitters/installers) and provide necessary construction shop drawings of latest revision.
Site supervisor/ foremen will also check that proper tools and equipment are available to carry out the work and are in compliance with contract specifications.
The Site supervisor and safety officer will explain to the tradesmen regarding safety precautions to be observed during the piping installation works.
Ensure that grid lines, reference levels etc. are marked by main contractor.
Site supervisor and foremen will carry out a site survey and mark the route of piping as per approved shop drawings.
In the event of any discrepancies or difficulties in executing the work, these shall be brought to notice of project engineer for corrective actions.
Coordination with other trades will be carried out while marking the route of piping.
Method of CHW Pipe Installation
Chilled water piping installation shall be as per manufacturers recommendations, and all the piping & fittings should be correctly used as per approved material submittals.
Install and connect the piping to allow adequate service space for equipment.
Make sure piping is free of sags or bends.
Diagonal runs are not permitted, unless expressly indicated on the drawings.
Horizontal run random lengths of pipe may be lifted into place using mechanical means or manual means, depending on the size of the pipe.
All pipes will be supported by hangers / supports at intervals as approved / recommended by the manufacturer/supplier and contract specifications.
Confirm that the installation of support hanger, bracket is securely fixed and is at the correct elevation.
Allow sufficient thread on threaded rods for pipe level adjustment. Upon satisfactory levelling cut back excess threaded rods and touch up with approved paints.
Install drains throughout systems to ensure that the entire system can be drained, this includes but is not limited to all low points, bases of all risers, and at each branch take off.
Install drains valves at low points in piping system mains and elsewhere as required.
Equipment condensate drains shall be trapped at equipment connection, drain lines shall run full size to nearest floor drain or as shown on drawings.
Do not install piping over electrical panel boards, switchgear, switchboards or motor control centres.
Install piping at right angle to slabs, beams, columns, walls, and other permanent elements of the building.
The Surface and internal pipes & fittings should be cleaned and free from grease and oil prior to threading.
Threading for the pipes should be done with appropriate threading machine.
Black steel size up to 50mm will be threaded and size 65mm and above will be welded.
Weld metal is to be thoroughly fused with base metal at all sections.
Welds shall be sound metal, free from laps, slag inclusion or other defects.
Teflon tape/cotton/jute should be wrapped prior to pipe joints.
For welded pipe and fittings the following shall apply:
a) Fit up the two ends to be welded as per the approved welding procedure.
b) Tack the two pieces together ensuring a uniform root gap and internal alignment.
c) Only welders holding a valid welders qualification certificate for the applicable welding procedure may weld any joints.
d) Each welder shall have a unique identification number. All welds shall bear this identification number of the welder.
e) Safety policy should be strictly followed in the place of welding.
Eccentric reducer fittings should be used in horizontal positions and concentric reducer fittings for vertical installations.
Welding of pipe in situation shall be minimized by the pre-fabrication of spools at ground level, or in the fabrication facility on site. Spools will be fabricated in manageable lengths, making allowance for the field weld location.
Site sketches will be prepared for all spools by the relevant engineer or supervisor.
Pipes shall be marked and cut square and cleanly by cutting disc or Oxy/Acetylene cutting torch as applicable.
Pipe ends will be prepared according to the type of joint, i.e. threaded, butt weld. Pipe ends for welded joints will be prepared by grinding as per the approved welding procedure.
On completion of pipe end preparation check to ensure the inside of the pipe is free of all dust and debris.
Where pipes penetrate through walls and floors sleeves of the appropriate size and type, according to the wall or floor type, shall be installed.
Pipes going through sleeves shall be independently supported of the sleeve as per an approved support detail.
All vibration isolators shall be installed as per approved shop drawings.
Pipes going through risers shall be supported from the building structure as per approved support details.
Proper clean out, Tees with dummy caps and drain valve should be installed as per site requirements.
Proper safety precautions should be taken for pipe installation in Shaft/risers with proper lifting tools.
Branch connections shall be made using standard fittings of the appropriate wall thickness or “Weld-o-lets”.
All high points shall have vents installed and all low points shall have drain points installed as indicated on the approved drawings or as identified on site.
All valves shall be installed as indicated on the approved drawings & manufacturers recommendations.
Valve orientation and flow direction shall be carefully checked, it should be in positions of maintenance.
Piping connection to Valves and Equipment:
a. DN50 and smaller: 2070 kPa brass seat unions for steel piping and with heavy semi-flushed brass unions on copper piping.
b. DN65 and larger: Flat face welding neck flanges for pressure 860kPa and less; raised face welding neck flanges for pressure above 860kPa.
Install strainers as indicated on the approved drawing.
Where piping crosses a building expansion joint approved expansion bellows or couplings shall be installed as per the manufacturer’s instructions.
Check to ensure that the correct type and size of gaskets have been installed at all flanged joints and that the bolt type, size and length are correct.
On completion of the works all elements of the installation shall be checked to ensure the installation is in compliance with the specifications.
Ensure all field engineering changes are approved and noted on the drawings as “Red Lined”.
All additional vents and drains shall be red Lined on the drawings.
Red Lined drawings shall be returned to the engineering department for the production of “As Built” drawings.
Prior to Pressure testing the system shall be inspected and as necessary a snag/punch list shall be issued by the QA/QC department.
On satisfactory completion of the punch list, the client will be requested to inspect the works.
Only when the client has inspected and such punch items as raised by the client cleared and approval given for leak testing, can such testing proceed.
An in-house test of the system will be performed prior to inviting the client to inspect the test for record purposes.
On satisfactory testing of the system, it shall be released for insulation.
Insulation should not be compressed with support and installation procedure for insulations should be as per manufacturer’s recommendations.
Provide space to permit insulation applications as per approved material submittal and Approved Shop drawings insulation detail.
Locate groups of pipes parallel to each other, spaced to permit applying full insulation and servicing of valves.
Ensure all the piping installation should follow the clearance from pipe to pipe and service to services as per approved shop drawings.
Identifications/Labels for Chilled water pipe works shall be as follows:
a. Identifications Labels for Chilled water pipe works services should be as per Approved Material submittal/Shop Drawings, Project Specifications and Manufacturers recommendations.
b. Identifications labels shall with stand climatic conditions. The Size, Font and Colors should be as per Approved Material Submittal, Project Specifications and Manufacturers recommendations.
c. Chilled water (Supply/Return) should have their own identifications with flow direction mark for future maintenance
d. Installations of Identifications labels should be as per Manufacturers recommendations.
HSE and Welfare Arrangements
All safety rules & regulation for the project shall be adhered to at all times.
Third party certified equipment’s and competent personnel to be deployed.
Required permit to be secured.
Risk assessment and risk control measures are to be in place.
All site personnel shall be properly equipped with protective clothing and tools appropriate for their duties and shall ensure that work area facilities are safe prior to the commencement of work activities.
All individual tasks mentioned in this method statement will be subject to individual, risk assessments and toolbox talks by safety officer in situ before work commences on daily basis.
No refueling is allowed whilst equipment is running, to be done only at designated area on the field.
Provide banks man or spotter during equipment maneuvering and during hauling of excavated materials.
All lifting tackle will be inspected before use.
All personnel will have undergone the applicable safety training and wear PPE i.e., Safety Helmet, Steel-Toed Safety Boots or Shoes, Safety Glasses and coveralls as the minimum requirement and gloves and High Vests where necessary.
For dusty working environment dust masks shall be used.
Works will proceed under controlled environment.
Control measures identified in the risk assessment to be in place.
Significant aspects related to dust and any other air contamination shall be controlled by dewatering.
Dust suppression shall be done by means of water sprinkling and dewatering.
After approval of this method statement, a pre-construction meeting to be held among the supervisory staff involved.
Trainings mentioned in the risk assessment to be followed.
- Inspection and Test Plan ITP
- Pipe Installation Checklist
- HSE Risk Assessment