Common parts on fixed, external floating and internal floating roofs, with the other names you'll hear on site. The drawings are sketches, not to scale. The blue part is the one named on the card. Tap Photos to see real ones.
the named partroof, shell, floor
Built by TankForge — API 653 inspection software
The Annex C checklist, tank drawings, UT readings and the finished report, on one iPad, from the tank deck — even with no signal.
Large bolted or hinged cover for getting into the tank or onto the floating deck. API 650 lists 20 in. and 24 in. roof manholes; internal floating roof deck manholes are 24 in. or larger.
FixedExternal floatingInternal floatingAPI 653 Annex C · C.1.5.1
A deliberately light roof-to-top-angle weld. In an internal explosion the roof tears off here so the shell and bottom stay intact. A roof welded to its rafters does not count as frangible (API 650 5.10.2.3).
Non-contact level instrument on a roof nozzle. The horn or cone points at the product surface. A servo gauge sits in the same kind of spot but hangs a displacer.
Roof carries itself on the shell with no internal columns. Common on smaller tanks. Plate thickness comes from a span and load formula (API 650 5.10.5), not a fixed minimum.
Carries rainwater from the deck out through the shell near the bottom. Either jointed pipe (articulated) or a flexible hose. Its valve at grade is normally open.
On the common mechanical type, a stem hangs below the deck. When the roof lands on its legs the stem hits the floor and pushes the cover open, so the roof doesn't pull a vacuum.
External floatingInternal floatingAPI 653 Annex C · C.1.5.11
Top rail about 42 in. high, a mid-rail halfway, and a toe board at the deck edge so tools can't roll off. These heights are OSHA (29 CFR 1910.29), not API.
FixedExternal floatingInternal floatingAPI 653 Annex C · C.1.6.1
Fixed ladder with hoops around the climber. OSHA now requires a ladder safety or fall-arrest system on new fixed ladders over 24 ft and is phasing cages out, so note what is fitted.