This comprehensive guide provides detailed weight charts for AISI 321 weld neck flanges.
Understanding Steel 321
Steel 321 (UNS S32100 / EN 1.4541) is a titanium-stabilized austenitic stainless steel designed for applications requiring resistance to intergranular corrosion after heating within the chromium carbide precipitation range of 800°F to 1500°F (427°C to 816°C) .
The titanium addition prevents chromium carbide precipitation during welding or elevated temperature service, making this grade particularly suitable for flanges that will be subjected to thermal cycling.
The density of Steel 321 is 8.0 g/cm³ (0.289 lb/in³) , a critical value that underpins all weight calculations.
Weld Neck Flange Introduction
Weld neck flange distinguishes itself through a long, tapered hub that provides a smooth transition from flange to pipe . This design has several benefits:
Stress distribution: The tapered hub gradually transmits mechanical loads from the flange ring into the pipe wall
Fatigue resistance: Reduced stress concentrations make these flanges ideal for cyclic loading conditions
Bore continuity: The flange bore matches the pipe bore, minimizing turbulence and erosion
Nondestructive testing access: The configuration facilitates radiographic inspection of the weld joint
These characteristics explain why weld neck flanges are specified for high-pressure, high-temperature, and critical service applications across oil and gas, petrochemical, power generation, and marine industries.
Steel 321 Weld Neck Flange Weight Charts
The following weight tables represent standard ASME B16.5 dimensions for ASTM A182 F321 weld neck flanges with raised faces. Weights are approximate and based on the density of 0.289 lb/in³.
Class 150 Steel 321 Weld Neck Flange Weights
|
NPS |
Pipe OD (in) |
Flange OD (in) |
Thickness (in) |
Hub Length (in) |
Weight (lbs) |
|
½" |
0.84 |
3.50 |
0.44 |
2.00 |
1.0 |
|
¾" |
1.05 |
3.88 |
0.50 |
2.06 |
1.5 |
|
1" |
1.32 |
4.25 |
0.56 |
2.19 |
2.0 |
|
1¼" |
1.66 |
4.62 |
0.62 |
2.25 |
2.5 |
|
1½" |
1.90 |
5.00 |
0.69 |
2.38 |
3.0 |
|
2" |
2.38 |
6.00 |
0.75 |
2.50 |
4.5 |
|
2½" |
2.88 |
7.00 |
0.88 |
2.75 |
6.5 |
|
3" |
3.50 |
7.50 |
0.94 |
2.75 |
8.0 |
|
4" |
4.50 |
9.00 |
0.94 |
3.00 |
13.0 |
|
6" |
6.63 |
11.00 |
1.00 |
3.50 |
23.0 |
|
8" |
8.63 |
13.50 |
1.12 |
4.00 |
37.0 |
|
10" |
10.75 |
16.00 |
1.19 |
4.19 |
52.0 |
|
12" |
12.75 |
19.00 |
1.25 |
4.50 |
77.0 |
|
14" |
14.00 |
21.00 |
1.38 |
4.75 |
95.0 |
|
16" |
16.00 |
23.50 |
1.44 |
5.00 |
125.0 |
|
18" |
18.00 |
25.00 |
1.56 |
5.25 |
150.0 |
|
20" |
20.00 |
27.50 |
1.69 |
5.56 |
185.0 |
|
24" |
24.00 |
32.00 |
1.88 |
6.00 |
260.0 |
Class 300 Steel 321 Weld Neck Flange Weights
|
NPS |
Flange OD (in) |
Thickness (in) |
Weight (lbs) |
|
½" |
3.75 |
0.56 |
1.4 |
|
¾" |
4.62 |
0.62 |
2.0 |
|
1" |
4.88 |
0.69 |
2.7 |
|
1¼" |
5.25 |
0.75 |
3.5 |
|
1½" |
6.12 |
0.81 |
5.0 |
|
2" |
6.50 |
0.88 |
6.5 |
|
2½" |
7.50 |
1.00 |
10.0 |
|
3" |
8.25 |
1.06 |
13.0 |
|
4" |
10.00 |
1.12 |
21.0 |
|
6" |
12.50 |
1.25 |
35.0 |
|
8" |
15.00 |
1.38 |
55.0 |
|
10" |
17.50 |
1.50 |
80.0 |
|
12" |
20.50 |
1.62 |
115.0 |
|
14" |
23.00 |
1.75 |
145.0 |
|
16" |
25.50 |
1.88 |
185.0 |
|
18" |
28.00 |
2.00 |
235.0 |
|
20" |
30.50 |
2.12 |
290.0 |
|
24" |
36.00 |
2.38 |
405.0 |
EN 1092-1 PN 10 Steel 321 Weld Neck Flange Weights
|
DN |
Pipe OD (mm) |
Flange OD (mm) |
Thickness (mm) |
Weight (kg) |
|
15 |
21.3 |
80 |
14 |
0.7 |
|
20 |
26.9 |
90 |
16 |
0.9 |
|
25 |
33.7 |
100 |
16 |
1.2 |
|
32 |
42.4 |
120 |
16 |
1.8 |
|
40 |
48.3 |
130 |
16 |
2.2 |
|
50 |
60.3 |
140 |
16 |
2.6 |
|
65 |
76.1 |
160 |
16 |
3.5 |
|
80 |
88.9 |
190 |
18 |
5.0 |
|
100 |
114.3 |
210 |
18 |
6.5 |
|
125 |
139.7 |
240 |
20 |
8.5 |
|
150 |
168.3 |
265 |
20 |
11.0 |
|
200 |
219.1 |
320 |
22 |
16.5 |
|
250 |
273.0 |
375 |
24 |
15.6 |
|
300 |
323.9 |
440 |
24 |
24.0 |
|
350 |
355.6 |
490 |
26 |
30.0 |
|
400 |
406.4 |
540 |
28 |
38.0 |
Note: The DN250 PN10 weight of 15.6 kg is verified from multiple supplier sources, demonstrating consistency across manufacturers.
In the demanding landscape of high-temperature industrial processing, material integrity is non-negotiable. As a senior product manager specializing in stainless steel and nickel alloys, I have seen firsthand how the choice of a flange can dictate the lifespan of a piping system. Among the various grades and configurations, the Steel 321 Weld Neck Flange (WNF) stands out as a critical component for applications where thermal cycling and intergranular corrosion are primary concerns.
This guide provides a comprehensive weight chart and technical analysis of Steel 321 Weld Neck Flanges, designed to assist engineers, procurement specialists, and project managers in precise system design and logistics planning.
Steel 321 Properties
Before diving into the weight specifications, it is vital to understand the material composition that justifies the use of Grade 321. Steel 321 is a titanium-stabilized austenitic stainless steel. While it shares many characteristics with Grade 304, the addition of titanium (at least five times the carbon content) serves a specific purpose: it eliminates chromium carbide precipitation during welding or exposure to high temperatures.
Chemical Composition of Steel 321
The stability of this alloy is what makes it the preferred choice for exhaust manifolds, heat exchangers, and pressure vessel components.
|
Element |
Content (%) |
|
Carbon (C) |
0.08 max |
|
Manganese (Mn) |
2.00 max |
|
Silicon (Si) |
0.75 max |
|
Phosphorus (P) |
0.045 max |
|
Sulfur (S) |
0.030 max |
|
Chromium (Cr) |
17.0 – 19.0 |
|
Nickel (Ni) |
9.0 – 12.0 |
|
Titanium (Ti) |
5×(C+N) min,0.70 max |
Physical and Mechanical Properties
From a mechanical perspective, Steel 321 offers superior creep and stress rupture properties compared to 304 or 304L.
Tensile Strength: ≥515 MPa
Yield Strength (0.2% Offset): ≥205 MPa
Elongation: ≥40%
Density: 7.92 g/cm3 (approx. 0.286 lb/in³)
Understanding the Weld Neck Flange Design
The Weld Neck Flange is distinguished by its long tapered hub, which provides an important reinforcement for applications involving high pressure, sub-zero temperatures, or elevated heat. The transition from the flange thickness to the pipe wall thickness provided by the taper is extremely beneficial under conditions of repeated bending, caused by line expansion or other variable forces.
The bore of the flange is machined to match the inside diameter of the pipe. This ensures there is no restriction in product flow, preventing turbulence and reducing erosion-corrosion at the joint.
Steel 321 Weld Neck Flange Weight Chart (ASME B16.5)
The following tables outline the estimated weights for Steel 321 Weld Neck Flanges across various pressure classes. Please note that weights are approximate and can vary slightly based on the specific manufacturer's tolerances and the "Schedule" (wall thickness) of the bore.
Class 150 Weld Neck Flanges
|
Nominal Pipe Size (NPS) |
Outside Diameter (in) |
Weight (lb) |
Weight (kg) |
|
1/2" |
3.50 |
2.0 |
0.9 |
|
1" |
4.25 |
3.0 |
1.4 |
|
2" |
6.00 |
7.0 |
3.2 |
|
4" |
9.00 |
17.0 |
7.7 |
|
6" |
11.00 |
26.0 |
11.8 |
|
8" |
13.50 |
45.0 |
20.4 |
|
12" |
19.00 |
88.0 |
39.9 |
Class 300 Weld Neck Flanges
|
Nominal Pipe Size (NPS) |
Outside Diameter (in) |
Weight (lb) |
Weight (kg) |
|
1/2" |
3.75 |
3.0 |
1.4 |
|
1" |
4.88 |
4.0 |
1.8 |
|
2" |
6.50 |
10.0 |
4.5 |
|
4" |
10.00 |
30.0 |
13.6 |
|
6" |
12.50 |
54.0 |
24.5 |
|
8" |
15.00 |
85.0 |
38.6 |
|
12" |
20.50 |
165.0 |
74.8 |
Class 600 Weld Neck Flanges
|
Nominal Pipe Size (NPS) |
Outside Diameter (in) |
Weight (lb) |
Weight (kg) |
|
1/2" |
3.75 |
4.0 |
1.8 |
|
1" |
4.88 |
8.0 |
3.6 |
|
2" |
6.50 |
15.0 |
6.8 |
|
4" |
10.75 |
49.0 |
22.2 |
|
6" |
14.00 |
105.0 |
47.6 |
|
8" |
16.50 |
165.0 |
74.8 |
|
12" |
22.00 |
325.0 |
147.4 |
Note: The weights provided are for standard Schedule 40 bores for Class 150/300 and Schedule 80 for Class 600. For heavier schedules (e.g., Sch 160 or XXS), the weight will increase due to the added mass in the hub and neck.
How to Calculate Steel 321 Flange Weight?
While charts are convenient, custom requirements often necessitate manual calculations. The weight of a Weld Neck Flange can be estimated by breaking it down into two geometric volumes: the disc (flange body) and the hub (tapered neck).
The general formula for the volume of the disc is:
Where:
D = Outside diameter
d = Inside diameter (bore)
T = Thickness
When calculating for Steel 321, we apply the density of 7,920 kg/m³. However, due to the complex geometry of the tapered hub, we recommend using our factory's proprietary calculators for exact structural engineering requirements.
How to Use the Weight Chart
Add flange weight to pipe, valves, and supports for accurate dead-load calculations. In transportation, multiply by quantity plus packaging to determine container payload. For cost estimation, our weights allow precise material and freight budgeting. Always verify the exact raised-face height and bore schedule (STD, XS, etc.) when ordering.
Why Choose Our Factory's Steel 321 Weld Neck Flanges
Customers return to us because every flange carries full material certification, dimensional reports, and hydrostatic test records (when specified).
Our production team averages over 15 years' experience with titanium-stabilized grades.
We maintain in-house spectrographic analysis and positive material identification (PMI) to guarantee chemistry.
Lead times are reliable, packaging is export-ready, and technical support is available 24/7 for flange selection or welding procedure qualification.
