This mechanical method statement covers the nature and type of work for the installation of chilled water CHW piping and Accessories in the project building and the frequency on which the inspections are to be carried out. The method also covers the installation and inspection of Chilled Water Piping including Accessories.
All the materials delivered to site are inspected properly and stored as per the manufacturer recommendations.
Request for inspection RFI shall be issued for the consultant’s approval.
All the piping installation work shall be carried out by the site staff under the strict supervision and guidance of the relevant and concerned site supervisors and engineers.
Site Engineer shall check as per the checklist, shall further checked by the Consultant. Request for Inspection shall be prepared by site quality engineer for inspection from the consultant.
Tools & Equipment
Below is an indicative hand tools list that shall be used for the installation of chilled water piping works.
Drilling Machine
Hammer
Sprit Level
Pipe Wrench
Grooving Machine
Thread Cutting Machine
Piping Tools Box
HSE Requirements
Only trained persons shall operate the power tools.
Ensure all concerned personals shall use PPE and all other items as required.
Make sure that adequate lighting is provided in the working area.
Ensure deep manhole excavations / shaft openings are protected with barricade, tape, safety nets.
Implement all the requirements in the approved job safety / risk assessment documents.
General Installation Requirements
All the piping, insulation and accessories materials delivered to site shall be inspected and stored properly as per the manufacturer recommendations.
Site engineer shall be fully responsible for making sure that work is carried out by the site staff as per quality requirements and good workmanship is always prioritized.
All chilled water pipes shall be painted with two coats of red oxide primer prior to application of insulation.
Open ends of the pipes shall be protected properly at the end of each day’s work.
Quality inspector and site engineer shall check the installations as per the approved inspection and testing plan ITP.
Request for inspection shall be prepared by site/quality engineer and shall be issued to consultant for inspection and approval.
Method of Installation of Chilled Water Pipes
Make sure and check the availability of sleeves as per approved shop drawings and specification, which is already completed during the construction of structural elements.
Piping connection 2” (inch) and below shall be made by threaded joints and piping connection 2-1/2 inch and above are made by using the grooved joints.
The piping grooves shall be done by using grooving machine and depth and width of a groove shall be maintained as per groove fitting manufacturer recommendations.
Mark the location of piping as per specification and approved shop drawing.
Install approved supports, brackets for piping as per specification, approved shop drawings and site requirements for each individual case (i.e.. Slab, soffit Wall etc.).
Supports shall be installed as per pipe manufacturer’s recommendations.
Readymade hardwood shall be used for supporting the vertical chilled water piping, which is placed on galvanized L angle or U channels and fastened with GI threaded rods.
Roller supports shall be installed for the pipes 200mm and above and in the expansion joints.
Install flexible pipe connectors in all building expansion joints and equipment piping connections.
Pipes shall be laid with gradient as per approved shop drawings and site conditions.
Drains shall be installed at low points in mains and branch lines consisting of gate valve and short threaded nipple and cap so that the system shall be drained completely.
Valves, Piping specialties and accessories shall be installed as per manufacturer recommendation and approved shop drawings.
Unions shall be provided in direction of flow after valves for sizes 2” and below & 2-1/2” and above flange connection shall also be provided.
All valves shall be installed suitably to permit easy access for future maintenance works.
Eccentric reducers shall be installed in Horizontal chilled water system & concentric reducers shall be installed in vertical chilled water system.
Automatic Air vents shall be installed at high points and wherever required in order to trap air from the chilled water system.
Condensate drain piping shall be connected to the equipment drain pan connections as per approved shop drawings.
Extend and connect the condensate drain piping to the nearest floor drain and connect to the main drain system.
Plug all open ends of pipes at the end of each day’s work using end caps.
Raise Request for Inspection of Installation of Chilled Water Piping and fittings including supports / brackets, valves, piping specialties and accessories as per the approved shop drawing.
After approval of installation of CHW pipes and fittings, flushing shall be done for chilled water pipes with clean water to remove dust and debris that might have been present during construction work.
Plug all connections / branches / drains and fill with clean water for hydro pressure testing of pipes.
Pressure Testing of Chilled Water Piping System
Care shall be taken to all the equipment’s, apparatus, devices to avoid pressure exceeding its prescribed test pressure as obtained from its name plate data or product catalogues.
Any equipment, apparatus and device that might be damaged by the test pressure shall be removed or blanked off.
Ensure All Valves are in open condition before starting pressure test, NO pressure shall be applied against closed valves.
Ensure Temporary blank flanges are anchored firmly in a way to accommodate all developed end trust.
The Piping system shall be tested by plugging and closing all openings in the system in proper way and filled slowly with water.
Ensure all system is free from air lock, if not release all the vent all entrapped air from the system.
Make sure that water is reaching to the entire system by releasing/opening the plugs temporarily.
Pressure shall be applied to the system by means of hand pump drawing the water from a water container.
The pump discharge shall be connected to the system through a globe valve, check valve and calibrated pressure gauge of suitable range to have the test pressure range in the middle of the range.
Perform cold water piping hydro test at 10 Bar Pressure for 24 hours.
Ensure that the test pressure is same at highest point of the system.
Repair the leaks and defects if any until satisfactory results are obtained i.e. piping system is leak proof.
Raise Request for Inspection of hydro testing to witness the same, by Consultant.
After approval of inspection of hydro testing, release the water gradually and protect the piping installation, and place end caps for pipes as required.
Insulation Method for Chilled Water Piping
Check all required approved chilled water pipe insulations materials are readily available on project site.
Approved 25mm thick closed cell rubber insulation pipe sections shall be used for up to 40mm diameter chilled water piping and 32mm thick for 50mm and above diameter chilled water pipes inside the building.
Mock-up for pipe insulation shall be provided for consultant review and approval before starting the main work.
Apply the approved insulation materials and accessories according to specification and manufacturer instructions.
Ensure all insulation materials are in dry condition during the application.
Pipe surface shall be cleaned properly and painted as per specification.
Apply insulation with longitudinal seams at top and horizontal pipe runs.
Pipe insulation shall be applied with least number of joints.
Apply only the approved adhesive in longitudinal seam and end faces of the insulation and entire pipe surfaces.
For flanges, elbows, fittings and valves mitered section of pipe insulation of same material shall be used.
Permissible access shall be maintained to the valves to operate without disturbing the insulation.
Removable type insulation sections shall be prepared and provided to valves including check valves and strainer basket and other valves.
In case of rising steam valves used in chilled water system, insulation shall be extended and insulation joints and valve specialties seams shall be sealed properly in order to prevent passage of air to pipe surface.
Aluminium tape of 75mm width shall be applied on the joints of insulation segments properly.
Pipe penetrations through roof, exterior wall, interior wall, fire rated wall, floor etc., through sleeves shall be closed by ram packed with loose fiber glass insulation and sealed with approved mastic and for fire rated walls approved fire proof sealant shall be used.
Use thermofoil recommended Tape to seal the joints in a way no air can penetrate through the joints.
Identification for Chilled Water Supply and return line and valves and specialties shall be done as per specification with approved identification materials.
Raise request for inspection RFI of insulation and identification of Chilled Water Piping and Accessories for consultant approval.
All inspection to be done as per approved quality control procedures and plans etc.