Shell opening reinforcement area (100% replacement rule) and fitting neck credit (ANSI/AWWA D103-09, §5.10)
◉ ANSI/AWWA D103-09 §5.10 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Genuinely different reinforcement philosophy from the existing API 650 and EN 14015 nozzle reinforcement calculators — this is a simple "100% replacement" rule (area removed by the hole must be replaced in full), not the partial-credit area formulas those standards use. Verified directly against this edition's page images. §6 (Sizing of Tanks) was checked and confirmed to have no standard capacity/diameter table — sizes are manufacturer-published, not tabulated in the standard itself.
Identification
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Required Reinforcement Area — 100% Replacement (§5.10.1)
Areq = max hole dimension × required shell thickness. Except for flush-type cleanout fittings, all effective reinforcement must be within a distance equal to the maximum hole dimension. Excess shell plate thickness (beyond what's needed for hydrostatic/structural loads, exclusive of bolted-joint requirements) may count toward this area, in either direction from the opening centerline.
Result
Required reinforcement area Areq—
Fitting Neck Reinforcement Credit (§5.10.2)
Credit toward the required area above: the neck portion within the shell thickness itself, plus the portion extending outward (and inward, if applicable) for a distance of 4× the neck wall thickness — or to the point of transition if the neck thickness isn't uniform over that distance.
Result
Credit zone, outward from shell surface—
Credit zone, inward from shell surface—
Shell Manhole Standard Sizes (§7.1.1, reference)
One manhole required in the first shell ring unless otherwise specified. Standard sizes: circular 24in (610mm) diameter; square 24×24in (610×610mm); elliptical 18×22in (460×560mm) minimum. Flush rectangular manholes: 24in (610mm) minimum in the shortest direction, 48in (1220mm) maximum in the longest, with 6in (150mm) minimum corner radius. Manhole reinforcing per §5.10 (this tool). Covers over 50 lb (23 kg) require a hinge or davit.