FLANGE STANDARD LIBRARYAX FORGE · SPEC SHEET
SPEC SHEETNo. 437
ASME B16.5 · ASME B16.5-2025

B16.5 Class 900 18″ Weld Neck

DN450Weld NeckDimensions mmWeight kg
ASME B16.5 · 18″ (DN450) · Class 900 · Weld Neck FlangeASME B16.5 · 18″ (DN450) · Class 900 · Weld Neck Flange O.D. D 787.4 Bolt circle K 685.8 20ר50.8 Raised face Ø 533.4 Thickness C 101.6 RF height f 6.4 Length H 228.6 Hub Ø A 565.2 Weld end Ø 457.2 Both views share one scale (1:15); schematic only Unit: mm

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

SymbolItemValue
DOutside diameter787.4mm
CFlange thickness / blind thickness101.6mm
D2Raised face diameter533.4mm
fRaised face height6.4mm
KBolt circle diameter685.8mm
nNumber of bolt holes20pcs
dBolt hole diameter50.8mm
AHub diameter565.2mm
HHub length / overall length228.6mm
BWelding-end diameter457.2mm
—Approximate weight308kg

Pressure–temperature ratings · Class 900 · Group 1.1

≤ 38 °C153.1 bar50 °C149.3 bar100 °C140.1 bar150 °C135.2 bar200 °C131.5 bar250 °C125.9 bar300 °C119.7 bar325 °C116.0 bar350 °C112.9 bar375 °C109.2 bar400 °C103.9 bar425 °C86.2 bar450 °C68.9 bar475 °C52.5 bar500 °C34.6 bar538 °C17.4 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