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SPECIFICATION · #403

B16.5 Class 600 1¼″ Weld Neck

ASME B16.5 · ASME B16.5-2025 · DN32

B16.5Class 600Weld NeckUnits mm / kg
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Dimension drawing

Schematic, drawn from the table values
ASME B16.5 · 1¼″ (DN32) · Class 600 · Weld Neck FlangeASME B16.5 · 1¼″ (DN32) · Class 600 · Weld Neck Flange O.D. D 133.4 Bolt circle K 98.6 4×Ø19.1 Raised face Ø 63.5 Thickness C 20.6 RF height f 6.4 Length H 66.5 Hub Ø A 63.5 Weld end Ø 42.2 Both views share one scale (1:2.4); schematic only Unit: mm

D outside diameter · K bolt circle · n×Ød bolt holes · C thickness · D2 raised face · f raised-face height · A hub diameter · H length

Dimensions

B16.5 · Class 600
DOutside diameter133.4mm
CFlange thickness / blind thickness20.6mm
D2Raised face diameter63.5mm
fRaised face height6.4mm
KBolt circle diameter98.6mm
nNumber of bolt holes4pcs
dBolt hole diameter19.1mm
AHub diameter63.5mm
HHub length / overall length66.5mm
BWelding-end diameter42.2mm
Approximate weight2.7kg
Data edition ASME B16.5-2025Verified 2026-11-04

Pressure–temperature ratings

≤ 38 °C102.0 bar50 °C99.6 bar100 °C93.4 bar150 °C90.1 bar200 °C87.6 bar250 °C83.9 bar300 °C79.8 bar325 °C77.3 bar350 °C75.3 bar375 °C72.8 bar400 °C69.3 bar425 °C57.5 bar450 °C45.9 bar475 °C35.0 bar500 °C23.0 bar538 °C11.6 bar

Current material group: Group 1.1

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

Maximum allowable working pressure in bar at the listed metal temperature. Values fall or stay level as temperature rises. Linear interpolation is allowed between the listed temperatures; interpolation between classes and any extrapolation are not.

Material & standard

B16.5
Standard
ASME B16.5 (ASME B16.5-2025)
Base material
ASTM A105
Material options
ASTM A105 / A105NASTM A350 LF2ASTM A182 F304/F316LASTM A182 F11/F22/F91ASTM A182 F51/F53
Region
North America, Middle East, South-East Asia

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, 2,220 psi (153.1 bar) at Class 900, 3,705 psi (255.1 bar) at Class 1500 and 6,170 psi (425.1 bar) at Class 2500 at 38 °C (100 °F), derating as temperature rises. The 2025 edition revised the rating tables (record 23-2509); these are the 2025 values and the full temperature tables are on the ASME B16.5 pressure-ratings page.

Dimension values on this page have been checked cell by cell against ASME B16.5-2025, using both the SI and U.S. Customary tables. The 2025 edition revised the bore (B) dimension figures and the minimum hub-height method, neither of which is a field published in these tables; outside diameter, thickness, hub, length, bolt circle and bolt-hole values match the 2025 edition. Raised-face height follows the 2025 rule: 1.5 mm for Classes 150 and 300, 6.4 mm for Classes 400 to 2500.

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RELATED

Related specifications

Same size · other pressure classes

Class 150D 117.3Class 300D 133.4Class 400D 133.4Class 900D 158.8Class 1500D 158.8Class 2500D 184.2

Same size and rating · other types

Slip-OnC 20.6BlindC 20.6

Adjacent sizes · Class 600

← 1″DN251¼″ · DN321½″ →DN40

Data note

Dimension values on this page have been checked cell by cell against ASME B16.5-2025, using both the SI and U.S. Customary tables. The 2025 edition revised the bore (B) dimension figures and the minimum hub-height method, neither of which is a field published in these tables; outside diameter, thickness, hub, length, bolt circle and bolt-hole values match the 2025 edition. Raised-face height follows the 2025 rule: 1.5 mm for Classes 150 and 300, 6.4 mm for Classes 400 to 2500.

Specification #403 · last updated 2026-11-05 08:05

Use limits

This library is a factual compilation of published standards tables. It does not replace the standard text. Verify against the edition in your purchase specification before quoting, manufacturing or inspecting a critical part.