FLANGE STANDARD LIBRARYAX FORGE · SPEC SHEET
SPEC SHEETNo. 434
ASME B16.5 · ASME B16.5-2025

B16.5 Class 900 12″ Weld Neck

DN300Weld NeckDimensions mmWeight kg
ASME B16.5 · 12″ (DN300) · Class 900 · Weld Neck FlangeASME B16.5 · 12″ (DN300) · Class 900 · Weld Neck Flange O.D. D 609.6 Bolt circle K 533.4 20ר38.1 Raised face Ø 381.0 Thickness C 79.2 RF height f 6.4 Length H 200.2 Hub Ø A 419.1 Weld end Ø 323.9 Both views share one scale (1:11); schematic only Unit: mm

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

SymbolItemValue
DOutside diameter609.6mm
CFlange thickness / blind thickness79.2mm
D2Raised face diameter381mm
fRaised face height6.4mm
KBolt circle diameter533.4mm
nNumber of bolt holes20pcs
dBolt hole diameter38.1mm
AHub diameter419.1mm
HHub length / overall length200.2mm
BWelding-end diameter323.9mm
—Approximate weight147kg

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