1. PURPOSE: This method statement covers on site installation of pre-fabricated ductwork systems for kitchen exhaust.
2. SCOPE OF WORK: This procedure is to define the method to be used to ensure that prefabricated ducting, bracketing, in line equipment installation, final connections and workmanship are correct and acceptable, and conforms to the contract documents and specifications.
- Construction Manager
- Mechanical HVAC Engineer/Supervisor
- Quality Control Inspector
- All materials and documentation relevant to a particular section of works shall be checked by the construction department prior to the commence of work ensuring that these are of the correct type as reviewed by the client.
- Before commencement any construction works, pre-inspections will be carried out on all materials prior to them leaving the storage area.
- Prior to the commencement of any construction works, areas and access will be inspected to confirm that they are in a suitable condition for construction works to commence and cleared by other contractors.
5. METHOD STATEMENT FOR INSTALLATION
- Ductwork Supervisor will instruct tradesmen regarding the execution of the works and will distribute all necessary approved construction drawings of the latest revision.
- The supervisor will also check that tools and equipment available are in compliance with the contract requirements.
- Ensure horizontal ductwork is adequately supported at equal distances with all brackets fixed to the vertical face of the ribbed beams of the structure.
- Care will be taken during setting out, that ductwork runs between ceiling module lines so as to maintain maximum flexibility for any future relocation of lighting fixtures, and other services.
- Ductwork supports unless otherwise indicated will be installed to provide a minimum space of 15mm between finished covering and adjacent work, and 200mm clearance from suspended ceiling.
- Supports or hangers will be placed within 300mm of any 45° – 90° bend.
- Ducts shall be supported within 300mm of mating flanges or joints.
- As indicated on relevant approved construction drawings where more than one duct can be supported on one hanger – the size of the hanger will be assessed on the sum of the maximum widths.
- Each horizontal section of kitchen exhaust duct will slope towards drainage points located in accessible locations adjacent to access panels at a maximum of 18m centers. Drain points will be a minimum of 25mm diameter and shall be sealed water tight with a suitable screwed plug.
- Ductwork passing through non-fire rated walls and floors will be adequately supported on either side.
- Supervisor will ensure that there are no dents, distortion or buckling of ducting during installation.
- Supports will be fixed at correct levels. Checks will be made to ensure the bracket material is compatible with installation and correct method used for fire rated sections..
- Ducting will be installed allowing sufficient space for expansion/contraction.
- Care will be taken during the mating of flanges that a continuous gasket is used to effectively seal flanges and corners.
- After flanges are sealed and securely bolted additional clips will be securely attached.
- Supervisor to ensure that access points are installed at every 3 meters, and on both sides and every change of direction, in accordance with approved details on contractor’s drawings.
- Continuously check horizontal and vertical alignment of ductwork and compliance with contractor’s drawings and specification requirements.
- In line equipment will be independently supported from main structure and not from blockwork walls or sub-structure.
- Fire dampers will be installed as contractor’s drawings and supported adequately.
- Supervisor to check before end of working day that :
a) ductwork supports are adequate.
b) all lockouts are tightened.
c) at all open end’s check for debris, then cover with suitable material to prevent any ingress of debris vermin, or moisture.
- Ensure terminal equipment is installed as specified.
- It will be ensured that all completed installations look neat and tidy, and that there is adequate spacing between ductwork and in line equipment allowing access for operation and ease of maintenance.
- The supervisor in charge and the QC officer will continuously monitor the activities to ensure that all components indicated on the approved drawings have been installed and that the installation is in accordance with the contract requirements and manufacturer’s recommendation.
- All completed installation work will be protected to avoid damage until final completion.
6. HSE CONSIDERATIONS
Include the specific health & safety requirements for the site, refer to health and safety requirements for working on height.
- Approved sonstruction shop drawings
- Mechanical specifications
- SMACNA or ASHRAE Specifications