316 stainless coastal outside air duct
Exterior marine/corrosive exposure
Before you start
- Confirm 316 stainless is required and verify all exposed fasteners, supports, anchors, isolation pads, sealants, and weather components are compatible with coastal service.
- Review wind, drainage, expansion, insulation, weatherproofing, and exterior support details.
- Inspect surfaces for carbon-steel contamination and protect the duct from salt-laden dirt during staging.
- Check that support coatings and attachments will not create crevice traps or galvanic contact.
Tools and materials
316 stainless duct and compatible fasteners, 316 or approved isolated supports, exterior-rated gaskets and sealants, drainage and weather-shedding components, expansion hardware where shown, soft slings, dedicated stainless tools, clean water and approved cleaner.
Lay it out
- Plan joints to shed water rather than hold it.
- Locate low points, drains, expansion points, and support attachments before lifting.
- Keep exterior joints and supports accessible for inspection and future cleaning.
Set and support it
- Use 316 stainless or approved isolated exterior supports and compatible anchors.
- Provide drainage paths under saddles, insulation jackets, and connection details.
- Support runs so thermal movement does not overload a joint or equipment connection.
Make the connection
- 1
Clean mating surfaces and remove any carbon-steel contamination.
- 2
Set the duct on compatible supports and verify drainage direction.
- 3
Complete the specified welded or gasketed exterior joint.
- 4
Install compatible fasteners and isolation materials.
- 5
Complete weather-shedding seals, flashing, and drainage details.
- 6
Provide expansion allowance where shown.
- 7
Wash and clean the installed surface after nearby metal work is complete.
Check the install
- No dissimilar-metal contact or rust contamination is present.
- Joints shed water and have no crevice or low pocket that traps saltwater.
- Drainage and expansion details remain functional.
- Support coatings, anchors, and fasteners are compatible.
- The installed surface is clean and the finish remains intact.
Common mistakes
- Using 304 or ordinary plated hardware in a 316 coastal system.
- Creating water traps under supports or insulation jackets.
- Leaving carbon-steel grinding dust on the stainless surface.
- Locking a long exterior run with no movement allowance.
Stop and ask
Stop if the support coating, anchor, fastener alloy, sealant, isolation method, drainage detail, or expansion requirement is incompatible or unverified.