Backup support counts for a landed floating roof during tank cleaning and entry (API RP 2016 §12.8)
◉ API RP 2016 §12.8 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Verified directly against the standard's own text. This recommended practice is largely procedural (permits, PPE, atmospheric testing) rather than formula-based — its own entry-safety thresholds (O₂, LEL, toxic substance limits) are explicitly deferred to API 2015 and applicable OSHA regulations, not stated here, so this tool doesn't include an atmospheric pass/fail check. What it does cover — temporary support counts for a floating roof landed for cleaning — is the one part of this document with genuine, self-contained numeric criteria.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.
Tank & Roof Basis
Floating roof leg designs typically carry roughly a 100% safety factor on dead load when properly pinned and not severely corroded (§12.8.3.1) — a qualified person's inspection (hammer test or UT) can establish whether a vertical load backup is even needed before relying on the counts below.
Not required at all if the guide pole (pipe) system is present, the seal is a shoe seal, and all components/attachments are in satisfactory condition.
Temporary Wood Leg Supports (§12.8.4)
Result
Legs nearest the shell manhole (fixed)3 (§12.8.4.1.1)
At each rim blocking point1 nearest leg per point (§12.8.4.1.2)
Additional supports by roof type—
Wood support specification (§12.8.4): 4×4 in. dry timber (green timber prohibited), strapped to the leg at both top and bottom so the support cannot move side to side. Temporary wood supports are never a substitute for the rim-seal blocking and anti-rotation system — they only back up the steel legs themselves (§12.8.4.3). All temporary supports must be removed once cleaning is complete (§12.8.4.4).