METHOD OF PART 2 STATEMENT FOR METAL DUCTWORK- LOW PRESSURE

 

METHOD OF PART 2 STATEMENT FOR METAL

 

DUCTWORK- LOW PRESSURE

Safety The Site Supervisor/Foreman The Safety Manager / Inspector The QC Inspector QC Supervisor Site Engineer Project Manager Responsibilities Hvacmep Standards Project Specification International Codes Purpose Scope of Work ABBREIONS PROCEDURES

METHOD OF PART 2 STATEMENT FOR METAL  DUCTWORK- LOW PRESSURE

METHOD OF PART 2 STATEMENT FOR METAL  DUCTWORK- LOW PRESSURE

G. Procedures:

        G.1 Handling and storage of duct:

 

Unload the duct by hand/ leader and store the duct inside the respective buildings or workshop area.

         Primary step:

 

§  Check approval of working drawings.

§  Check site clearance for work.

§  Check wall /slab opening as per approved drawings.

§  Notify to client representative for inspection of receiving factory made duct.

G.3 DUCT WORKS, HANGERS AND SUPPORT INSTALLATION:

 1.     Supports for Rectangular ducts when suspended from above shall be installed on two opposite side of each duct.

2.      The support system shall not cause corrosion by galvanic action at points of contact with the duct.

3. Concrete fasteners shall be installed after the concrete has been  poured andtheforms

            have been removed.                                                                                               

4. The support system shall not penetrate enclosures containing fluids or electrical wiringin such a manner to create a hazard.           

5. When ducts are supported from wall they shall be located against      the wall or maximum

            of 2” away from wall.                                                                                 

6.     The supports system shall not penetrate a bearing member in such a manner as to cause excessive loading on the member.

METHOD OF PART 2 STATEMENT FOR METAL  DUCTWORK- LOW PRESSURE

 

7.      Circular bands shall not be less than one inch wide not less than equivalent to the gauge

            of the duct material does it support.                                                                

8.      Ducts shall be equipped with tight circular bands extending around the entire perimeter

            of the duct at each specified support interval.                                                            

9. Rectangular duct risers from floor shall be supported by angles or channels secured  to

            the sides of duct with welds, bolts, sheet metal screws, or blind rivets. Fasteners shall be

            Located within 2” of the duct edges, locate others at evenly spaced interval.                       

10. Angles/Channels shall be at 12 feet intervals for rectangular and        round duct risers. All

            Duct hanger & supports details shall be according to the drawing.                                     

 11. Mark the routing of the ducts and install GI threaded rod and angle/channel supports.

 METHOD OF PART 2 STATEMENT FOR METAL  DUCTWORK- LOW PRESSURE

G.4 DUCT MATERIAL:

 

1.     Factory made Duct Work shall be installed in accordance with IFC/shop Drawings, Specifications, and Manufacturer's Installation.

2.     Rectangular elbows shall be provided with Turning Vanes. 

3.  Ducts shall be isolated from their Air Handling System (Fan, Fan Coil, AHU’s, etc.) by flexible Connections. 

4.     Splitter dampers shall not be used for duct branch take-offs

     5.     Installation of duct shall be done with proper alignment.

      6.     All duct work shall comply with SMACNA standards.

7.     All ducts shall be flash / blow with air to ensure of free from dust and foreign objects prior to installation.

     8.     Material Specifications: 

·   Material Confirms to: ASTM A653

 

·   Material: Galvanized Iron sheets.

 

·   Zinc Coating: G-90.

 

·   Thickness: As per General Construction Drawings.

 METHOD OF PART 2 STATEMENT FOR METAL  DUCTWORK- LOW PRESSURE

G.5 DUCT INSULATION:

1.     Duct joints shall be sealed with approved sealant prior to insulation.

 

2.  Apply the sealant outside of the duct between the gap and corner and also apply inside of the duct (wherever is possible).

3.     Stick self-adhesive aluminum alloy sticker pins (1 pin/ 0.16m²) to the bare duct firmly.

 

4.     Duct Surface to be cleaned properly before applying adhesive 

5.  In case of requirement, the Light test shall be performed with heavy duty halogen lamps (500 or 1000Watts lamps), which will located inside the ducting and the leakage in the ducts shall be traced and sealed properly with the sealant or Smoke tests shall be done by igniting smoke emitters inside the duct to produce white smoke and checking for any leakage from any joints. If the duct volume is more, then a blower will be used to spread the smoke. Any leakage will be traced and sealed properly. 

6.  Mechanical fasteners, adhesive, tapes, metal straps or any other means at the intervals specified in the construction drawings or specification shall be used in the installation of the duct insulation.

7.     Paste the bonding adhesive glue on the bare duct. 

8.     All joints to be insulated after completion of duct leak test (lighting test). 

9.     Insulation applied to the exterior surface of ducts located in buildings shall have a flame 

             Spread index of not more than 25 and a smoke density index not      exceeding 50 when\tested                 as  a   composite  installation including insulation, facing  material,tapes and adhesive as                         normally applied.

10. All  Supply  and  return  air  ducts  for conditioned  air,  concealed  above  the  false  ceilingshall  be  insulated  with  25mm  thick    blanket. Ducts  shall be  insulated  in mentioned below:                                                                   

11. Materials specifications: 

• Material: Fiberglass blanket Insulation

• Density: 48 kg /m3
• ThermalConductivity:  0.034   w/mºC at24ºC  mean temperature. 
• FlameSpread / Smoke developed rating: 25/50 or less.
• Thickness: 25 mm.                 
• Fiber glass roll mat wraps shall beoverlapped  by at least100mm and shall be fastened

 

With 65mm wide aluminum foil tape and tape shall be overlapped by 15mm.

 

13. Fix the four corner clips (thickness of the clips shall be the same as duct gauge) and tight the insulation with aluminum band. 

14. Ensure that duct shall be clean and all open ends shall be covered in a suitable manner to prevent from dust and debris,

G.6 FLEXIBLE DUCTS, GRILLS AND DIFFUSERS AND VOLUME DAMPER INSTALLATION: 

1.      Check the dimension and locationof the wall/slab/ceiling opening per  the IFC

Drawings when ever  necessary.                                                                                                         

2.      Flexible ducts shall be installed in accordance with SMACNA standard as per      IFC

Drawings                                                                                                

3.      The bends of the flexible ducts shall not exceed  45 Degrees. The length of the flexible duct shall not exceed 1.5 meters.                                                                                     

4. The flexible ducts shall be supported every 1.5 meters (Max.) to avoid it from sagging       And touching the false ceiling.                    

5. Connect both ends of flexible duct with stainless steel clamp                                                         

6. Install the grilles and diffusers properly and dampers with respect to the air flow Direction as per IFC drawings.                                                                                                                     

7. Grills and diffusers shall be installed to distribute the amount of air in every room. Refer to approved Standard detail drawing.                                                                                              

8. Grills and registers shall be installed with self-tapping screws to the wall or to the Ducts as per shop drawings.                                                         

            9. Supply grills or registers shall be installed with volume dampers easily adjustable from

The front.       

10. Return grills or registers shall be installed without deflectors and volume Dampers. The type of the diffusers shall be in accordance with the false ceiling.                                    

11. Supply ceiling diffusers shall be installed with deflectors and volume       Dampers.The type of the diffusers shall be in accordance with the false ceiling.                                                

12. Return ceiling diffusers shall be installed without volume dampers, and it shall be the same model with the supply diffusers. If the return diffusers is not the same with Supply, the size and model shall be as specified in the shop drawings.

     13. Air terminal devices shall not be installed directly on the main ducts

           14. Supply& Return linear bar grill, with plenum& opposite blade damper. 

      15. All volume dampers shall be installed in accordance with SMACNA standard and HVAC IFC drawings.

16. Multiplied dampers shall be used on ducts sizes more than 12" depth, the blades must be opposed type.

           17. All volume dampers operated manually shall have a handle which can be lock to a certain setting.

     18. Install dampers and access doors as per approved drawing.

 

G.7 ELECTRICAL DUCT HEATER:

 

1.     All duct heaters shall be installed in accordance with SMACNA standard or equivalent.

 

2.     The duct heater elements shall be free of any debris or other materials which will create combustion. 

3.     The duct heater elements shall be installed 100% along the air stream so that the air will flow to the elements.

4.     An access door of 12" x 12" (min.) opening shall be provided on each Duct heaters for maintenance. 

5.     The location of the duct heaters shall be as specified in the approved IFC drawings. 

6.         Install electrical and control wiring in accordance with unit wiring diagrams, NEC and local standards