Spiral Round Ducting Installation Methods: Complete HVAC Guide for Efficient Air Distribution
In this article, we’ll explore the installation and insulation process for spiral round ducting and its accessories.
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Spiral round ducting is one of the most reliable and efficient solutions in modern HVAC (heating, ventilation, and air conditioning) systems. Its spiral seam enhances strength, reduces leakage, and improves airflow efficiency.
In this guide, we’ll walk you through the step-by-step installation and insulation methods for spiral round ducting, including tools, safety measures, and quality control checks. Whether you’re an HVAC professional, engineer, or student, this article provides practical insights and industry-standard techniques.
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| Spiral Round Ducting Installation Methods for HVAC Systems |
Basic Features of Spiral Round Ducting
Construction:
- Made from galvanized steel, stainless steel, Aluminium, or PVC.
- Manufactured by forming metal strips into a continuous spiral seam.
Advantages:
✔️ Higher Strength: The spiral seam adds rigidity, reducing the need for additional reinforcements.
✔️ Leakage Resistance: Minimizes air leakage compared to traditional rectangular ducts.
✔️ Cost-Effective: Requires less material and labor for installation.
✔️ Smooth Airflow: The round shape reduces turbulence and enhances efficiency.
✔️ Aesthetic Appeal: Often used in exposed duct work designs for industrial or modern interiors.
Common Applications:
✔️ HVAC systems in commercial and industrial buildings.
✔️ Ventilation and exhaust systems in factories and kitchens.
✔️ Underground duct systems for air distribution.
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| Applications |
Sizes & Fittings:
- Available in various diameters, typically ranging from 4 inches to 60" inches.
- Can be connected using fittings like elbows, reducers, and couplings.
INSTALLATION🔧
Scope and Purpose:
This Method Statement covers the on site installation of Spiral round ducting and duct accessories and the requirement of checks to be carried out.
Reference Documents📝
- Project Specifications,
- Approved shop drawings (latest revision),
- Approved material submittals,
- Duct work standard OW 144,
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General Materials🔍GI Spiral round ducting generally installed in for Fan Coil unit (FCU) return air, and supply air as shown in approved shop drawing includes:
- Spiral round ducting,
- Fittings such as Elbows,
- Tees,
- Couplings,
- Reducers,
- Collars etc,
- Volume control dampers,
- Flexible ducting insulation,
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| General Materials |
General Equipment📏
- Portable grinding Machine,
- Drilling Machine,
- Sheet metal cutting tools and bender,
- Spirit level,
- Scaffolding,
- Duct erector hand tools,
- Testing instruments,
- Air Compressor,
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| General Equipment |
Responsible Persons:
- Project Engineers,
- Construction In-Charge,
- Site Engineer and Site supervisor,
- QA and QC Inspectors,
- Safety officer,
- Site Foremen,
- Pipe fitters and Welders,
- Helpers.
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| Responsible Persons |
Method of per Installation💡
- Ensure that approved material required to carryout work will be available.
- Prior to commencement of work, area and access will be inspected to confirm that the site is ready to commence the work.
- Ensure all GI spiral ducting is pre-fabricated, labelled with tag numbers, and matches the specifications and dimensions in the approved drawings.
- All relevant documentation and material applicable to particular section of works will be checked by site engineer before commencement.
- Physical verification of material will be carried out for any damages prior to taking from stores.
- The site engineer or supervisor will give necessary instruction to tradesman and provide necessary construction shop drawings.
- The site engineer or supervisor will also check that tools and equipment available are in compliance to contract requirements.
- The site supervisor also explains tradesman regarding safety pre-cautions to be observed.
Method of Installation🛠️
- Prior to commencement of work coordination will be done with other services.
- Determine the position of duct supports as per approved Shop drawings and coordinated layouts and specification.
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| approved Shop drawings |
- Prepare and fix the duct supports as per approved construction drawing and specification.
- Any cut edges of angles, channels or threaded rods will be touch up with Zinc rich paint.
- Transport the Duct pieces and fittings to final location.
- Before assembly ensure that all ducts are free from dirt.
- Check that ducts and fittings are undamaged. This is specially important with regard to the rubber gaskets.
- Assemble the Duct pieces and fittings as per approved shop drawing ensuring the alignment.
- Push the fittings into the duct right to the stop, Turning the fitting a little makes insertion easier.
- Fasten fittings to the duct with self tapping screws or centered pop rivets.
- Distribute the screws or pop rivets evenly around the circumference, ensuring the rubber gaskets are not damaged i.e. placing them approximate 10mm from stop and end of the duct. In the event of incorrect assembly, holes caused by screws or pop rivets must be sealed.
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| pop rivets |
- Raise the duct work on to the supports ensuring that each length is aligned and leveled with preceding length as per dimensions shown on approved shop drawings.
- Ensure that duct work is clean and no tools/ construction debris exists within duct work before proceeding to next length.
- All open ends of the duct works shall be temporarily sealed with polythene Sheets/ply wood before leaving the job site to prevent moisture and dirt.
- Ensure that all accessories like Volume control dampers, Test points, Sensors are installed in accordance with approved shop drawings.
- Installation of duct work (complete with accessories) shall be checked before applying insulation at joints.
- Insulation of duct work will be completed as per manufacturer's recommendations (copy enclosed).
- Ensure the duct surface is clean and dry before re-applying any insulation material, Apply thinner /cleaner where necessary to make the area grease free.
- Apply glue recommended by manufacturer with an even spread on complete surface of insulation sheet.
- Once the glue on the sheet gets dry, apply glue on the GI duct and let it dry, then stick the sheet on one end and slowly press the sheet on the duct from one end to the other so as to ensure that the sheet sticks on the GI duct completely avoiding air bubbles between the insulation sheet and GI duct.
- In the areas where the GI duct comes into contact with the duct hangers, rigid support is recommended such as wood.
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| duct hanger and layer |
- The wood piece should be glued onto the duct hanger and layer of rubber to be glued on the wood, so that there is no direct contact between the duct insulation and the wooden piece thus preventing tearing of the duct insulation.
- In case the positioning of the support is available in advance, wood by itself can be used.
- In this case it has to be made sure that insulation will be glued to the wood from both sides accordingly.
- Where insulated duct work passes through fire rated wall/partitions the gap between sleeve and duct work shall be filled with approved fire barrier.
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| fire barrier |
Quality Control:
- QCE along with Project Engineer and site Supervisor will monitor that all components are installed as per the contract specifications and approved submittals.
- Inspection Request (IR) shall be submitted to the Main Contractor/Consultant during the following stages.
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| Quality Control |
- Mock up installation of GI spiral round ducting before and after insulation.
- After complete insulation.
Safety:
- Work will commence as per safety regulations laid down in the contract specification and project safety plan.
- Proper safety harness to be used and secured, if required.
- All personal protective equipment shall be used as appropriate according to the nature of job.
- Housekeeping shall be of good standard and all cut lengths and debris shall be removed.
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| safety regulations |
Conclusion🎯
Proper installation of spiral round ducting ensures long-lasting performance, energy efficiency, and optimal airflow in HVAC systems. By following the methods outlined here, you can reduce air leakage, enhance durability, and meet project standards with confidence.
Looking for more HVAC guides? Explore our detailed posts on fan coil unit installation, chilled water systems, and duct work best practices.
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