FLANGE STANDARD LIBRARYAX FORGE · SPEC SHEET
SPEC SHEETNo. 397
ASME B16.5 · ASME B16.5-2025

B16.5 Class 400 20″ Weld Neck

DN500Weld NeckDimensions mmWeight kg
ASME B16.5 · 20″ (DN500) · Class 400 · Weld Neck FlangeASME B16.5 · 20″ (DN500) · Class 400 · Weld Neck Flange O.D. D 774.7 Bolt circle K 685.8 24ר41.3 Raised face Ø 584.2 Thickness C 69.9 RF height f 6.4 Length H 168.1 Hub Ø A 587.2 Weld end Ø 508.0 Both views share one scale (1:12); schematic only Unit: mm

Schematic — drawn from the table, not to scale for inspection.

SymbolItemValue
DOutside diameter774.7mm
CFlange thickness / blind thickness69.9mm
D2Raised face diameter584.2mm
fRaised face height6.4mm
KBolt circle diameter685.8mm
nNumber of bolt holes24pcs
dBolt hole diameter41.3mm
AHub diameter587.2mm
HHub length / overall length168.1mm
BWelding-end diameter508mm
—Approximate weight193kg

Pressure–temperature ratings · Class 400 · Group 1.1

≤ 38 °C68.0 bar50 °C66.4 bar100 °C62.3 bar150 °C60.1 bar200 °C58.4 bar250 °C56.0 bar300 °C53.2 bar325 °C51.6 bar350 °C50.2 bar375 °C48.5 bar400 °C46.2 bar425 °C38.3 bar450 °C30.6 bar475 °C23.3 bar500 °C15.4 bar538 °C7.7 bar

Source: Table 2-1.1 (printed p. 25) — pressure–temperature ratings for Group 1.1 materials, SI units; Group 1.1.

Material and notes

Base material: ASTM A105 (North America, Middle East, South-East Asia)

Rating: ASME classes are not fixed pressures. For ASTM A105 (material group 1.1) the ASME B16.5-2025 ambient rating is 285 psi (19.6 bar) at Class 150, 740 psi (51.0 bar) at Class 300, 985 psi (68.0 bar) at Class 400, 1,480 psi (102.0 bar) at Class 600, 2,2…

Tolerances / marking: Tolerances, facing finish, material and marking requirements: ASME B16.5-2025 Sections 6 and 7.

Notes / special requirements

Work order Inspector Date Travels with the part; file after inspection