Toolbox / Flange BOM
Flange Weight & BOM Calculator: Flanges, Gaskets, Studs and Nuts
Flanges, gasket, stud bolts and heavy hex nuts for a joint, with dimensions from the standards tables and weights computed from geometry. Pick a standard, material and construction; studs, nuts and gasket metals are preselected from the material.
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Bill of materials
| Item | Specification | Qty | Unit kg | Unit lb | Total kg | Total lb |
|---|
Material and construction
Flange
Gasket
Fasteners (per joint)
How this is calculated
- Flange: weight from solid geometry (disc, hub, raised face, less bore and bolt holes) using B16.5-2020 dimensions and nominal steel densities. Thickness and hub length exclude the raised face, as in the 2017+ editions. RTJ flanges are weighed as raised-face flanges (groove metal not deducted).
- Studs: diameter, count and length read from the selected standard's drilling table (EN 1092-1 gives no bolt length: an estimate is used, with ISO 261 threads and ISO 4032 nuts). Weight is a threaded rod at the ASME B1.1 tensile-stress-area diameter over the full length; chamfered ends are ignored.
- Nuts: ASME B18.2.2 heavy hex, across flats = 1.5d + 1/8 in, thickness = d - 1/64 in, hexagonal prism less a bore at the thread minor diameter; chamfers ignored. Two nuts per stud.
- Gaskets: ASME B16.20 (spiral wound, ring joint) and B16.21 (flat ring, full face). Spiral wound: 4.5 mm wound element (30 % 304 strip, 70 % graphite by volume, 3.08 g/cm³) plus a 304 inner ring and a carbon-steel outer ring, each 3.2 mm thick (nominal 1/8 in). CAF 1.7 g/cm³, PTFE 2.15 g/cm³, ring joint soft iron 7.85 g/cm³.
- Material and pairing: density from the material catalogue (unverified densities are flagged); studs, nuts and gasket metals are recommended from the material and can be overridden. Clad, lined and galvanized weights follow the stated geometric assumptions.
- Quantity: a joint is 2 flanges + 1 gasket + 1 bolt set. In "flanges" mode an odd count rounds the gaskets and bolt sets up to whole joints.
- Estimating tool: confirm against the manufacturer's drawing before ordering.
Frequently asked questions
How is flange weight calculated?
From the flange geometry in the standard: outside diameter, thickness, hub and bore, minus the bolt holes, multiplied by the material density. Published catalogue weights vary between makers, so the calculator computes from the dimensions and states the convention it uses.
What is in a flanged joint bill of materials?
Two flanges, one gasket and one set of stud bolts with two nuts each. The calculator lists each item with its specification, quantity and weight, so the joint can be ordered and shipped as one package.
What is the difference between ASME B16.5 and B16.47?
ASME B16.5 covers flanges from NPS ½ to 24. B16.47 covers NPS 26 to 60 in two series that do not interchange: Series A (based on MSS SP-44) and Series B (based on API 605), which is lighter with more, smaller bolts.
Which studs and nuts go with carbon steel flanges?
The common pairing for carbon steel flanges is ASTM A193 B7 studs with A194 2H heavy hex nuts. Low-temperature, stainless and alloy flanges use other grades; the calculator pre-selects the bolting for the flange material you choose.
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