Weld Neck Flanges

Weld-Neck flanges or welding-neck flanges can be differentiated from all other types of flange by their long tapered hub. In addition, there is also a gentle transition of thickness in the region of the butt weld that joins them to pipe or a fitting. Weld-Neck flanges or welding-neck flanges are best suited for severe service conditions, whether loading conditions are substantially constant or fluctuate between wide limits.

Weld Neck Flanges

Weld Neck Flanges

Weld Neck Flanges are flanges with the wall thickness of the flange having the same dimensions of the matching pipe, the lighter the pipe is, the larger the bore, conversely, the heavier the pipe, the smaller the bore, they are normally used for high pressure, cold or hot temperature.

The various types of steel weld neck flanges are:

Standards, Dimensions & Weight

Meterial & Standard for flanges:

CARBON STEEL

ASTM A 105, ASTM A 181

Alloy Steel

ASTM A 182, GR F1, F11, F22, F5, F9, F91

Nickel Alloys
Monel 400 & 500, Inconel 600 & 625, Incolloy 800, 825, Hastelloy C22,C276

Copper Alloys
Copper, Brass & Gunmetal

Size
1/8″ NB TO 48″NB.

Class
150#, 300#,400 #,600#,900#, 1500# & 2500 #.

Standard ANSI
ANSI B16.5, ANSI B16.47, MSS SP44, ANSI B16.36, ANSI B16.48

DIN
DIN2527, DIN2566, DIN2573, DIN2576, DIN2641, DIN2642, DIN2655, DIN2656, DIN2627, DIN2628, DIN2629, DIN 2631, DIN2632, DIN2633, DIN2634, DIN2635, DIN2636, DIN2637, DIN2638, DIN2673

B.S
BS4504 , BS4504, BS1560, BS10

ANSI Series A Weld Neck Flange
Series A 150,300 Weld Neck Flange
Series A 400, 600 & 900 Weld Neck Flange
400, 600 & 900 Weld Neck Flange

Dimensional Tolerances of Weld Neck Flanges ASME B16.5

Dimensions are in millimeters unless otherwise indicated.

OUTSIDE DIAMETER

≤ 24 = 1.6 mm
> 24 = ± 3.2 mm

INSIDE DIAMETER

≤ 10 = ± 0.8 mm
≥ 12 = + 1.6 mm / – 0 mm

DIAMETER OF CONTACT FACE

1.6 mm Raised Face = ± 0.8 mm
6.35 mm Raised Face
Tongue & Groove / Male-Female = ± 0.4 mm

DRILLING

Bolt Circle = 1.6 mm
Bolt Hole Spacing = ± 0.8 mm
Eccentricity of Bolt Circle with Respect to Facing
≤ 2½ = 0.8 mm max.
≥ 3 = 1.6 mm max.

DIAMETER OF COUNTERBORE

Same as for Inside Diameter

OUTSIDE DIAMETER OF HUB

≤ 12 = + 2.4 mm / – 1.6 mm
≥ 14 = ± 3.2 mm

THICKNESS

≤ 18 = + 3.2 mm / – 0
≥ 20 = + 4.8 mm / – 0

LENGTH THRU HUB

≤ 18 = + 3.2 mm / – 0.8 mm
≥ 20 = + 4.8 mm / – 1.6 mm

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