FLANGE STANDARD LIBRARYAX FORGE · SPEC SHEET
SPEC SHEETNo. 343
ASME B16.5 · ASME B16.5-2025

B16.5 Class 150 2½″ Weld Neck

DN65Weld NeckDimensions mmWeight kg
ASME B16.5 · 2½″ (DN65) · Class 150 · Weld Neck FlangeASME B16.5 · 2½″ (DN65) · Class 150 · Weld Neck Flange O.D. D 177.8 Bolt circle K 139.7 4ר19.1 Raised face Ø 104.6 Thickness C 20.6 RF height f 1.5 Length H 68.3 Hub Ø A 90.4 Weld end Ø 73.2 Both views share one scale (1:3.9); schematic only Unit: mm

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

SymbolItemValue
DOutside diameter177.8mm
CFlange thickness / blind thickness20.6mm
D2Raised face diameter104.6mm
fRaised face height1.5mm
KBolt circle diameter139.7mm
nNumber of bolt holes4pcs
dBolt hole diameter19.1mm
AHub diameter90.4mm
HHub length / overall length68.3mm
BWelding-end diameter73.2mm
—Approximate weight3.6kg

Pressure–temperature ratings · Class 150 · Group 1.1

≤ 38 °C19.6 bar50 °C19.1 bar100 °C17.7 bar150 °C15.8 bar200 °C13.8 bar250 °C12.1 bar300 °C10.2 bar325 °C9.3 bar350 °C8.4 bar375 °C7.4 bar400 °C6.5 bar425 °C5.5 bar450 °C4.6 bar475 °C3.7 bar500 °C2.8 bar538 °C1.4 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