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Valve Standard Reference

ASME B16.25

American

Buttwelding Ends

ASME B16.

Overview — ASME B16.25

ASME B16.25 defines the dimensional requirements for butt-welding ends on pipes, fittings, valves, and other components. It specifies bore diameters, wall thickness schedules, end bevel angles, and transition contours at butt-weld joints to ensure that two different components can be welded together without creating stress concentrations or misaligned bores. Compliance with B16.25 is essential for any valve that will be welded into a piping system.

Scope

Covers butt-welding ends for pipes, flanges, fittings, valves, and other components in carbon steel, stainless steel, and alloy steel. Addresses Schedule 10 through Schedule 160 and XXS wall thicknesses. Includes both standard and heavy-wall transition contours.

Applicable Valve Types

All valve types with butt-weld end connections

Ball Valves, Gate Valves, Globe Valves, Check Valves (BW ends)

Applicable Pressure Classes

All pressure classes with BW ends

Key Requirements — ASME B16.25

01.

Bore diameter must match pipe schedule bore within ±1/32 inch (±0.8 mm)

02.

End bevel angle: 37.5° ± 2.5° for standard wall; compound bevel for heavy-wall

03.

Transition taper: 1:3 taper ratio (18°) for wall thickness mismatch ≤1/8 inch

04.

Root face: 1/16 inch ± 1/32 inch for standard bevel

05.

Heavy-wall transition: three-zone compound bevel for schedules 120, 160, XXS

06.

Material identification marks must be visible after end preparation

Testing Requirements — ASME B16.25

Dimensional verification of bore diameter and bevel angle

Visual inspection of end preparation

Documentation Required for ASME B16.25 Compliance

Dimensional inspection report confirming B16.25 compliance

Material Test Reports (MTR)

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