Method Statement Title: Installation and testing of Chilled Water Piping

Method Statement Title: Installation and testing of Chilled Water Piping

1.0       Scope :

1. This method statement applies to installation, pressure testing, insulation and cladding of chilled water piping including valves and accessories, as per specification 15010, 15050, 15180, 151700.

2.0       Purpose :

• Purpose of this method statement is to outline the method of storage, handling, fabrication, installation, pressure testing, insulation and cladding of chilled water piping including valves and accessories.

3.0       Material :

• Pipes

ERW, black steel, SCH 40, Grade ‘B’ 

• Fittings

Upto 50mm dia. MI fittings, Black, threaded ends

65mm dia and above – Steel Butt welding type/Grooved coupling joint type.   

• Valves

Upto 50mm                 :           Threaded ends

65mm and above        :           Flanged ends

• Accessories

Pressure gauges, thermometer, test points, airvents, water meters, etc.

• Elastomeric Closed cell insulation, adhesives.

• Supporting Materials

Clevis hangers, MS angles / channels, threads rods, anchor fasteners etc. As per attached sketches.

4.0       Method :

• Storage :

• All material while unloading shall not be dropped, but slowly lowered to the ground. 

• For pipes, wooden supports shall be placed beneath at equal distance. 

•  Pipes shall be stacked on a flat surface with adequate supports.

•  End caps of pipes shall be in place until removed for installation.

• While stacking, it shall be ensured that pipes of bigger sizes are placed below and smaller sizes on top.

• All pipes shall be covered and shall not be exposed to direct sunlight.

• All other items such as valves, fittings, gauges, etc. shall be kept on racks within site stores and shall be segregated as per size, model, type etc. for easy retrieval.

• Elastomeric insulation shall be stored in manufacturer’s packing and shall not be exposed direct sun light.

• Insulation material shall be segregated as per size, thickness for easy retrieval.

• The adhesive material shall be stored in a covered and ventilated storage area.

• All supporting materials shall be stored in a covered storage area, segregated according to size, type, model, etc. for easy retrieval. 

• Manufacturers instructions for storage shall be followed for applicable items.

• Any items found damaged or not suitable as per project requirements shall be removed from site. If required to store temporarily, they shall be clearly marked and stored separately to prevent any advertent use. 

• Preparation :            

• Check and ensure all drawings used for installation are latest and approved for construction.

•  Mark the pipe routing and support locations in the trench as per approved drawings.

• Check the co-ordination of piping layout with other services and decide pipe route with minimum bends/offsets.

• Check and ensure sufficient clearance around pipe for applying insulation / cladding as applicable.

• Check the access and clear space around valves, vent points, drain points locations for maintenance and servicing.

• Fabricate the structural supports form MS angles/channels as per support schedule as required.

• Clean and apply primer / red oxide on all ERW black pipes. 

• Installation :

• Drill the holes in trench wall for fixing supports.

•  Fix the anchors and threaded rods with clevis hangers / structural supports as applicable. Threaded rod length shall be sufficient to allow for levelling of piping. Supports details as per attached sketches.

• Cut the pipes accurately to measurements determined at site.

• Prepare the pipe ends according to the type of joints ie. threaded joints, welded joints / grooved coupling joints.

• The end preparation shall be done at site work shop.

• For grooved joints pipe end should be square and cut with machine.

• Flow process of grooving the pipe will incorporate a 1 Mtr long sprit level at least two nos. of  pipe stands for 6 Mtr long pipe and a completion check for squareness.

• Threading and grooving as applicable shall be done as per fittings / coupling manufacturers recommendations.

• End preparations for welded joints shall be done as per approved welding procedure. Refer Method Statement MS-017 Rev. 02.

• After the end preparation clean the pipe ends and ensure no material and dust is left inside.

• Depending on site conditions, assemble the piping into manageable lengths on the floor. Using threaded, welded/groove coupled jointing as applicable.

• Qualified and approved welders with current certificates shall be engaged for welding works.

• Install the pipe sections at heights as per approved drawing in a neat and tidy manner.

• Insert the approved hard insulating material of suitable thickness between the pipe and support.

• Align and level the piping as per approved drawings.

• Sleeves of suitable sizes shall be provided at wall crossings.

• Expansion grooved couplings shall be installed at locations as designated by specialist (Victaulic)

• Hole saw cutter shall be used to cut the holes in the pipe work for fixing branch connections for Victualic fittings.

• Install the valves in locations as per approved drawings.

• Install the piping connections with valves and accessories wherever equipments are installed as per approved drawings.

• Fix the blind plugs / temporary valves on all drain, air vent, pressure gauge, thermometer and test points tappings approved drawings.

• Check and ensure proper supporting is provided as per approved drawings.

• Make temporary tapping provisions at multiple points for easy and quick filling and draining of pressure testing water.

• Ensure all joints are properly tightened in line with manufacturer recommendation. 

• While installation is going on of the pipe work, the insulation will be fitted to the pipe work prior to pressure testing as explained in 4.5 pipe insulation. But all fittings and joints will be left exposed until the pressure testing and inspection is completed.

• Raise the “WIR” for piping installation by NMX QA/QC and consultant. Obtain signoff  for hydraulic pressure testing.

Note :  For installation and testing of chilled water piping (Preinsulated)  Refer MS: M/002.A.

• Pressure Testing :

• The chilled water piping shall be tested according to the system working pressure and PN ratings of the pipes, pipe fitting and valves used in the piping. 

• The piping may be tested in sections or in total, depending on site requirements.

• Estimate the piping volume and make arrangement for required quality of clean water.

• Arrange for temporary piping / hose pipe connections for filling and draining the water.

• Fix the temporary valves at air vent / drain points and pressure gauges.

• Fill the piping system with clean water.

• During initial filling, employ sufficient man power to monitor the entire length of the piping system for possible leakages.

• If leakages are observed, arrest the leakage immediately. If leakages are major, isolate the leaking portion with nearest isolating valve and / or stop the water filling.

• Rectify the leakages and again fill wit water.

• Ensure no leakages throughout the entire piping system.

• Observe for the leakages and pressurise the system using hydraulic test pump.

• During pressurisation observe the joints and entire piping system for leakages.

• Pressurise the system till pressure on the pressure gauge at lowest part of the system indicates pressure.

• Observe the pressure gauges readings for 8 hours and ensure there is no drop in gauge pressure.

• Raise the “WIR” for witnessing the hydraulic pressure testing by NMX QA/QC and consultant.

• Obtain signoff with clearance for insulation only after satisfactory pressure testing.

• Pipe Insulation

• The pipe surface shall be thoroughly cleaned to remove dust, traces of oil, grease etc. All welded joints are painted with red oxide primer.

• For smaller pipe sizes, pre-formed insulation pipe section of suitable thickness, as per approved drawings/submittals to be used. For larger pipe sizes insulation sheet shall be used in thickness described in the materials submittal.

• Smaller pipe which are not exposed to direct sunlight and insulation is not susceptible for damage, insulation may be done by inserting the pipes in to insulation sections during pipe installation.

• When insulation is done after pressure testing following procedure shall be followed.

• Slit the pipe insulation section, longitudinally and apply adhesive on inner surface and longitudinal slit as recommended by manufacturer.

• Apply the adhesive on the surface of the pipe to be insulated, as recommended by manufacturer.

• Fix firmly the insulation on the pipe surface and hand press the insulation to remove any air locks. The longitudinal seam shall be joined properly by hand pressing.

• Fix the elastomeric self adhesive tape over the longitudinal seam.

• Continue the same procedure for successive lengths. Adhesive shall be applied on circumferential joint properly. Seal the circumferential joint by fixing self adhesive tape.

• For larger pipe sizes, cut the insulation sheet of suitable width to suit pipe size. The length shall be as manageable as per site conditions.

• Complete the insulation as explained earlier in point No. 4.5.6. to 4.5.9.

• Under no circumstances insulated pipes shall be exposed to direct sunlight.

• Vapour seal must be achieved 100%.

• Raise the “WIR” for NMX QA/QC and consultants and obtain the signoff for cladding wherever applicable.

5.0       Inspection

• “WIR” by NMX QA/QC and Consultant shall be raised for piping installation, pressure testing, joint insulation and signed by Consultant.

• Inspection shall be carried out as per installation checklist during installation, testing and insulation stages.

• The entire installation work shall be supervised by the supervisors/engineers.

• Safety

• All safety precautions shall be followed as per established project safety plan and procedure.

• Warning signs shall be displayed while carrying out pressure testing.

• Only experienced and skilled technicians shall be engaged for carrying out installation and testing work.

• The people involved in the installation shall used PPE such as safety helmets, safety shoes, helmets, gloves etc. as required.

6.5       Safety office shall check and ensure that all safety precautions are followed.

• Safety office shall check and ensure chat all scaffolding and ladders used at site are having duly signed tags.
  • Hot work permit to be obtained before welding.

• Records

7.1       “WIR” duly singed by ETA/NMX QA/QC and consultant for

1. Piping Installation
2. Pressure Testing
3. Insulation