FLANGE STANDARD LIBRARYAX FORGE · SPEC SHEET
SPEC SHEETNo. 461
ASME B16.5 · ASME B16.5-2025

B16.5 Class 2500 1″ Weld Neck

DN25Weld NeckDimensions mmWeight kg
ASME B16.5 · 1″ (DN25) · Class 2500 · Weld Neck FlangeASME B16.5 · 1″ (DN25) · Class 2500 · Weld Neck Flange O.D. D 158.8 Bolt circle K 108.0 4ר25.4 Raised face Ø 50.8 Thickness C 35.1 RF height f 6.4 Length H 88.9 Hub Ø A 57.2 Weld end Ø 33.5 Both views share one scale (1:5.1); schematic only Unit: mm

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

SymbolItemValue
DOutside diameter158.8mm
CFlange thickness / blind thickness35.1mm
D2Raised face diameter50.8mm
fRaised face height6.4mm
KBolt circle diameter108mm
nNumber of bolt holes4pcs
dBolt hole diameter25.4mm
AHub diameter57.2mm
HHub length / overall length88.9mm
BWelding-end diameter33.5mm
—Approximate weight5.4kg

Pressure–temperature ratings · Class 2500 · Group 1.1

≤ 38 °C425.1 bar50 °C414.9 bar100 °C389.1 bar150 °C375.4 bar200 °C365.1 bar250 °C349.7 bar300 °C332.6 bar325 °C322.3 bar350 °C313.7 bar375 °C303.4 bar400 °C288.6 bar425 °C239.4 bar450 °C191.4 bar475 °C145.7 bar500 °C96.0 bar538 °C48.4 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