Stainless Steel 304 Flanges
Stainless Steel 304 flanges are manufactured from UNS S30400, an austenitic 18-8 grade containing 18 to 20% chromium and 8 to 10.5% nickel. The composition gives these flanges the ability to resist corrosion in atmospheric, mildly acidic, and alkaline conditions. They have good mechanical strength from cryogenic temperatures to 870°C. SS 304 flanges are some of the most commonly specified flanges for process piping, used in chemical processing, food and beverage, water treatment, pharmaceuticals, and general engineering applications where cost-effective corrosion resistance and good weldability are required.
Approx Price Range
The approximate price of SS 304 flanges per kg, and the factors affecting their prices, are explained below.
Price Per kg
SS 304 flanges are priced at roughly ₹175 to ₹240/kg. The larger sizes and higher pressure class cost more per unit. Ask your supplier about the per-piece price on larger flanges.
Factors Affecting Price
Nickel and chromium market rates, flange type, pressure class, NPS size, surface finish, certification requirements, and order volume all affect the final cost of UNS S30400 flanges.
Types of Stainless Steel 304 Flanges
SS 304 flanges are available in a full range of types to suit different piping configurations, pressure ratings, and installation methods.
- Weld Neck Flanges (WNRF)
- Slip-On Flanges (SORF)
- Blind Flanges (BLRF)
- Socket Weld Flanges (SWRF)
- Threaded Flanges
- Lap Joint Flanges
- Orifice Flanges
- Reducing Flanges
- Long Weld Neck Flanges
- Spectacle Blind Flanges
- Ring Type Joint Flanges (RTJ)
- Flat Face Flanges (FF)
UNS S30400 Flanges Specifications
The table below covers the key specification parameters for Stainless Steel 304 flanges as per international standards.
|
Parameter |
Details |
|
Standard |
ASTM A182 / ASME SA182 |
|
Dimensions |
ASME B16.5, B16.47 Series A & B, B16.48, DIN, BS4504, EN-1092, JIS B2220 |
|
Pressure Classes |
150#, 300#, 400#, 600#, 900#, 1500#, 2500# / PN6 to PN250 |
|
Size Range |
NPS 1/2" to 48" / DN15 to DN1200 |
|
Facing |
Raised Face (RF), Ring Type Joint (RTJ), Flat Face (FF), Tongue & Groove |
|
Manufacture |
Forged, Cast, Rolled, Plate |
|
Finish |
Plain, Pickled & Passivated, Electro-polished |
Chemical Composition of ASTM A182 F304 Flanges
The composition below confirms the 18-8 chromium-nickel balance that gives SS 304 flanges their corrosion resistance and weldability across a wide range of environments.
|
Element |
Composition (%) |
|
Carbon (C) |
0.08 max |
|
Chromium (Cr) |
18.0 – 20.0 |
|
Nickel (Ni) |
8.0 – 10.5 |
|
Manganese (Mn) |
2.0 max |
|
Silicon (Si) |
0.75 max |
|
Phosphorus (P) |
0.045 max |
|
Sulphur (S) |
0.030 max |
|
Nitrogen (N) |
0.10 max |
|
Iron (Fe) |
Balance |
Mechanical Properties of SS 304 Flanges
The mechanical values below apply to ASTM A182 Grade F304 forged flange material.
|
Property |
Value |
|
Tensile Strength |
515 MPa (75,000 psi) min |
|
Yield Strength (0.2% offset) |
205 MPa (30,000 psi) min |
|
Elongation |
40% min |
|
Hardness |
Max 92 HRB |
Physical Properties of Stainless Steel 304 Flanges
The physical properties below help engineers assess thermal behaviour and suitability for elevated or cryogenic temperature service.
|
Property |
Value |
|
Density |
7.93 g/cm³ |
|
Melting Range |
1399 – 1454°C (2550 – 2650°F) |
|
Specific Heat |
500 J/kg·°C |
|
Thermal Conductivity |
16.2 W/m·K (at 100°C) |
|
Electrical Resistivity |
0.72 µΩ·m |
|
Modulus of Elasticity |
193 GPa |
|
Coefficient of Thermal Expansion |
17.2 µm/m°C (0–100°C) |
Dimension Chart of Stainless Steel 304 Flanges
The table below lists standard weld neck raised face (WNRF) flange dimensions for SS 304 per ASME B16.5 Class 150.
|
NPS (in) |
DN (mm) |
OD (mm) |
Bore (mm) |
PCD (mm) |
Thickness (mm) |
Bolt Holes |
|
1/2 |
15 |
88.9 |
34.9 |
60.3 |
35.1 |
4 x 1/2" |
|
3/4 |
20 |
98.6 |
42.9 |
69.9 |
38.1 |
4 x 1/2" |
|
1 |
25 |
108.0 |
50.8 |
79.4 |
42.9 |
4 x 1/2" |
|
1.1/2 |
40 |
127.0 |
73.0 |
98.4 |
52.3 |
4 x 1/2" |
|
2 |
50 |
152.4 |
92.1 |
120.7 |
58.7 |
4 x 5/8" |
|
3 |
80 |
190.5 |
127.0 |
152.4 |
68.3 |
4 x 5/8" |
|
4 |
100 |
228.6 |
157.2 |
190.5 |
73.0 |
8 x 5/8" |
|
6 |
150 |
279.4 |
215.9 |
241.3 |
82.6 |
8 x 3/4" |
|
8 |
200 |
342.9 |
269.9 |
298.5 |
95.3 |
8 x 3/4" |
|
10 |
250 |
406.4 |
323.8 |
362.0 |
101.6 |
12 x 7/8" |
|
12 |
300 |
482.6 |
381.0 |
431.8 |
114.3 |
12 x 7/8" |
|
14 |
350 |
533.4 |
412.8 |
476.3 |
123.8 |
12 x 1" |
|
16 |
400 |
596.9 |
469.9 |
539.8 |
130.2 |
16 x 1" |
|
18 |
450 |
635.0 |
533.4 |
577.9 |
139.7 |
16 x 1.1/8" |
|
20 |
500 |
698.5 |
584.2 |
635.0 |
149.2 |
20 x 1.1/8" |
|
24 |
600 |
812.8 |
692.2 |
749.3 |
165.1 |
20 x 1.1/4" |
Dimensions per ASME B16.5 Class 150. Other pressure classes and flange types are available on request.
Size Chart of ASTM A182 F304 Flanges
Stainless Steel 304 flanges are available across a wide size range to cover standard and large-bore piping systems.
|
Standard |
Size Range (NPS) |
Size Range (DN) |
Pressure Classes |
|
ASME B16.5 |
1/2" – 24" |
DN15 – DN600 |
150# to 2500# |
|
ASME B16.47 Series A |
26" – 60" |
DN650 – DN1500 |
150# to 900# |
|
ASME B16.47 Series B |
26" – 60" |
DN650 – DN1500 |
75# to 900# |
|
DIN / EN 1092-1 |
DN15 – DN1200 |
DN15 – DN1200 |
PN6 to PN250 |
|
BS 4504 |
1/2" – 48" |
DN15 – DN1200 |
PN6 to PN64 |
|
JIS B2220 |
10A – 1500A |
DN10 – DN1500 |
5K to 63K |
Pressure Rating Chart of UNS S30400 Flanges
The pressure-temperature ratings below apply to SS 304 (Group 2.2) flanges per ASME B16.5. Values are the maximum allowable working pressures in bar at the listed temperature.
|
Temp (°C) |
Class 150 (bar) |
Class 300 (bar) |
Class 400 (bar) |
Class 600 (bar) |
Class 900 (bar) |
Class 1500 (bar) |
|
-29 to 38 |
19.6 |
51.1 |
68.1 |
102.1 |
153.2 |
204.2 |
|
50 |
19.2 |
50.1 |
66.7 |
100.1 |
150.1 |
200.1 |
|
100 |
17.7 |
46.6 |
62.1 |
93.2 |
139.8 |
186.3 |
|
150 |
16.1 |
42.6 |
56.8 |
85.3 |
127.9 |
170.5 |
|
200 |
14.8 |
38.6 |
51.5 |
77.3 |
115.9 |
154.6 |
|
250 |
13.4 |
35.4 |
47.2 |
70.8 |
106.2 |
141.6 |
|
300 |
12.1 |
32.4 |
43.2 |
64.8 |
97.2 |
129.6 |
|
375 |
10.2 |
27.4 |
36.6 |
54.8 |
82.2 |
109.6 |
|
425 |
8.6 |
22.8 |
30.4 |
45.6 |
68.3 |
91.1 |
|
450 |
7.4 |
19.3 |
25.8 |
38.6 |
57.9 |
77.2 |
Key Features of Stainless Steel 304 Flanges
SS 304 flanges are a dependable standard choice for general process piping. Here are the properties that make them widely specified.
- Reliable corrosion resistance in atmospheric, mildly acidic, and oxidising environments
- Good weldability with standard austenitic filler metals
- No post-weld heat treatment required in most cases
- Wide temperature service range
- Non-magnetic in the annealed condition
- Easy to clean and maintain
Applications of ASTM A182 F304 Flanges
SS 304 flanges are a standard choice in many industries due to their corrosion resistance, strength, and ready availability.
- Chemical processing
- Food and beverage
- Pharmaceutical manufacturing
- Water and wastewater treatment
- Power generation
- Oil and gas
- Pulp and paper
- Architectural and construction
How to Choose the Right Stainless Steel 304 Flanges Supplier?
Keep the following things in mind while choosing the right SS 304 flanges supplier.
Supplier Selection Criteria
Begin with inventory availability of multiple flange types, sizes, and pressure classes. A dependable supplier carries WNRF, SORF, and blind flanges in Class 150 and Class 300 as stock for standard NPS sizes. For large bore or high-pressure classes, check that the supplier can source or manufacture to order within your project lead time. If your project requires international specifications, it’s worth verifying experience with both ASME and DIN standards.
Technical Considerations
Ask for material test certificates for chemical composition and mechanical properties as per ASTM A182 and ASME SA182. Verify carbon content is within 304 limits (max 0.08%) for welded assemblies vs. supplied as 304L without documentation. Check your pressure class and NPS against the flange dimensions. For process flanges, check facing type (RF, FF, or RTJ) matches your gasket and bolting specification.
Quality and Certification Check
EN 10204 / 3.1 mill test certificates with heat number traceability are the baseline. For critical process flanges, it is advisable to ask for PMI (positive material identification) test reports on finished flanges to verify material identity. ISO 9001 certification is the minimum standard for suppliers. Check the CE marking and the compliance with EN 1092-1 in case of PED applications. Material shall be tested in accordance with ASME Section II Part A material specifications for ASME code applications.
Procurement Tips for Bulk Orders
SS 304 prices are closely linked to LME nickel. Schedule your procurement and lock-in rates for long-term projects in times of market stability. Bulk purchase of standard sizes can be done to ensure supply continuity and cost reduction. Request samples and dimensional inspection reports before approving a full production run. Confirm delivery timelines in writing. Allow extra lead time for machining, plus standard forging lead times for flanges with special facing or custom bore.
Stainless Steel 304 flanges are manufactured from UNS S30400, an austenitic 18-8 grade containing 18 to 20% chromium and 8 to 10.5% nickel. The composition gives these flanges the ability to resist corrosion in atmospheric, mildly acidic, and alkaline conditions. They have good mechanical strength from cryogenic temperatures to 870°C. SS 304 flanges are some of the most commonly specified flanges for process piping, used in chemical processing, food and beverage, water treatment, pharmaceuticals, and general engineering applications where cost-effective corrosion resistance and good weldability are required.
Approx Price Range
The approximate price of SS 304 flanges per kg, and the factors affecting their prices, are explained below.
Price Per kg
SS 304 flanges are priced at roughly ₹175 to ₹240/kg. The larger sizes and higher pressure class cost more per unit. Ask your supplier about the per-piece price on larger flanges.
Factors Affecting Price
Nickel and chromium market rates, flange type, pressure class, NPS size, surface finish, certification requirements, and order volume all affect the final cost of UNS S30400 flanges.
Types of Stainless Steel 304 Flanges
SS 304 flanges are available in a full range of types to suit different piping configurations, pressure ratings, and installation methods.
- Weld Neck Flanges (WNRF)
- Slip-On Flanges (SORF)
- Blind Flanges (BLRF)
- Socket Weld Flanges (SWRF)
- Threaded Flanges
- Lap Joint Flanges
- Orifice Flanges
- Reducing Flanges
- Long Weld Neck Flanges
- Spectacle Blind Flanges
- Ring Type Joint Flanges (RTJ)
- Flat Face Flanges (FF)
UNS S30400 Flanges Specifications
The table below covers the key specification parameters for Stainless Steel 304 flanges as per international standards.
|
Parameter |
Details |
|
Standard |
ASTM A182 / ASME SA182 |
|
Dimensions |
ASME B16.5, B16.47 Series A & B, B16.48, DIN, BS4504, EN-1092, JIS B2220 |
|
Pressure Classes |
150#, 300#, 400#, 600#, 900#, 1500#, 2500# / PN6 to PN250 |
|
Size Range |
NPS 1/2" to 48" / DN15 to DN1200 |
|
Facing |
Raised Face (RF), Ring Type Joint (RTJ), Flat Face (FF), Tongue & Groove |
|
Manufacture |
Forged, Cast, Rolled, Plate |
|
Finish |
Plain, Pickled & Passivated, Electro-polished |
Chemical Composition of ASTM A182 F304 Flanges
The composition below confirms the 18-8 chromium-nickel balance that gives SS 304 flanges their corrosion resistance and weldability across a wide range of environments.
|
Element |
Composition (%) |
|
Carbon (C) |
0.08 max |
|
Chromium (Cr) |
18.0 – 20.0 |
|
Nickel (Ni) |
8.0 – 10.5 |
|
Manganese (Mn) |
2.0 max |
|
Silicon (Si) |
0.75 max |
|
Phosphorus (P) |
0.045 max |
|
Sulphur (S) |
0.030 max |
|
Nitrogen (N) |
0.10 max |
|
Iron (Fe) |
Balance |
Mechanical Properties of SS 304 Flanges
The mechanical values below apply to ASTM A182 Grade F304 forged flange material.
|
Property |
Value |
|
Tensile Strength |
515 MPa (75,000 psi) min |
|
Yield Strength (0.2% offset) |
205 MPa (30,000 psi) min |
|
Elongation |
40% min |
|
Hardness |
Max 92 HRB |
Physical Properties of Stainless Steel 304 Flanges
The physical properties below help engineers assess thermal behaviour and suitability for elevated or cryogenic temperature service.
|
Property |
Value |
|
Density |
7.93 g/cm³ |
|
Melting Range |
1399 – 1454°C (2550 – 2650°F) |
|
Specific Heat |
500 J/kg·°C |
|
Thermal Conductivity |
16.2 W/m·K (at 100°C) |
|
Electrical Resistivity |
0.72 µΩ·m |
|
Modulus of Elasticity |
193 GPa |
|
Coefficient of Thermal Expansion |
17.2 µm/m°C (0–100°C) |
Dimension Chart of Stainless Steel 304 Flanges
The table below lists standard weld neck raised face (WNRF) flange dimensions for SS 304 per ASME B16.5 Class 150.
|
NPS (in) |
DN (mm) |
OD (mm) |
Bore (mm) |
PCD (mm) |
Thickness (mm) |
Bolt Holes |
|
1/2 |
15 |
88.9 |
34.9 |
60.3 |
35.1 |
4 x 1/2" |
|
3/4 |
20 |
98.6 |
42.9 |
69.9 |
38.1 |
4 x 1/2" |
|
1 |
25 |
108.0 |
50.8 |
79.4 |
42.9 |
4 x 1/2" |
|
1.1/2 |
40 |
127.0 |
73.0 |
98.4 |
52.3 |
4 x 1/2" |
|
2 |
50 |
152.4 |
92.1 |
120.7 |
58.7 |
4 x 5/8" |
|
3 |
80 |
190.5 |
127.0 |
152.4 |
68.3 |
4 x 5/8" |
|
4 |
100 |
228.6 |
157.2 |
190.5 |
73.0 |
8 x 5/8" |
|
6 |
150 |
279.4 |
215.9 |
241.3 |
82.6 |
8 x 3/4" |
|
8 |
200 |
342.9 |
269.9 |
298.5 |
95.3 |
8 x 3/4" |
|
10 |
250 |
406.4 |
323.8 |
362.0 |
101.6 |
12 x 7/8" |
|
12 |
300 |
482.6 |
381.0 |
431.8 |
114.3 |
12 x 7/8" |
|
14 |
350 |
533.4 |
412.8 |
476.3 |
123.8 |
12 x 1" |
|
16 |
400 |
596.9 |
469.9 |
539.8 |
130.2 |
16 x 1" |
|
18 |
450 |
635.0 |
533.4 |
577.9 |
139.7 |
16 x 1.1/8" |
|
20 |
500 |
698.5 |
584.2 |
635.0 |
149.2 |
20 x 1.1/8" |
|
24 |
600 |
812.8 |
692.2 |
749.3 |
165.1 |
20 x 1.1/4" |
Dimensions per ASME B16.5 Class 150. Other pressure classes and flange types are available on request.
Size Chart of ASTM A182 F304 Flanges
Stainless Steel 304 flanges are available across a wide size range to cover standard and large-bore piping systems.
|
Standard |
Size Range (NPS) |
Size Range (DN) |
Pressure Classes |
|
ASME B16.5 |
1/2" – 24" |
DN15 – DN600 |
150# to 2500# |
|
ASME B16.47 Series A |
26" – 60" |
DN650 – DN1500 |
150# to 900# |
|
ASME B16.47 Series B |
26" – 60" |
DN650 – DN1500 |
75# to 900# |
|
DIN / EN 1092-1 |
DN15 – DN1200 |
DN15 – DN1200 |
PN6 to PN250 |
|
BS 4504 |
1/2" – 48" |
DN15 – DN1200 |
PN6 to PN64 |
|
JIS B2220 |
10A – 1500A |
DN10 – DN1500 |
5K to 63K |
Pressure Rating Chart of UNS S30400 Flanges
The pressure-temperature ratings below apply to SS 304 (Group 2.2) flanges per ASME B16.5. Values are the maximum allowable working pressures in bar at the listed temperature.
|
Temp (°C) |
Class 150 (bar) |
Class 300 (bar) |
Class 400 (bar) |
Class 600 (bar) |
Class 900 (bar) |
Class 1500 (bar) |
|
-29 to 38 |
19.6 |
51.1 |
68.1 |
102.1 |
153.2 |
204.2 |
|
50 |
19.2 |
50.1 |
66.7 |
100.1 |
150.1 |
200.1 |
|
100 |
17.7 |
46.6 |
62.1 |
93.2 |
139.8 |
186.3 |
|
150 |
16.1 |
42.6 |
56.8 |
85.3 |
127.9 |
170.5 |
|
200 |
14.8 |
38.6 |
51.5 |
77.3 |
115.9 |
154.6 |
|
250 |
13.4 |
35.4 |
47.2 |
70.8 |
106.2 |
141.6 |
|
300 |
12.1 |
32.4 |
43.2 |
64.8 |
97.2 |
129.6 |
|
375 |
10.2 |
27.4 |
36.6 |
54.8 |
82.2 |
109.6 |
|
425 |
8.6 |
22.8 |
30.4 |
45.6 |
68.3 |
91.1 |
|
450 |
7.4 |
19.3 |
25.8 |
38.6 |
57.9 |
77.2 |
Key Features of Stainless Steel 304 Flanges
SS 304 flanges are a dependable standard choice for general process piping. Here are the properties that make them widely specified.
- Reliable corrosion resistance in atmospheric, mildly acidic, and oxidising environments
- Good weldability with standard austenitic filler metals
- No post-weld heat treatment required in most cases
- Wide temperature service range
- Non-magnetic in the annealed condition
- Easy to clean and maintain
Applications of ASTM A182 F304 Flanges
SS 304 flanges are a standard choice in many industries due to their corrosion resistance, strength, and ready availability.
- Chemical processing
- Food and beverage
- Pharmaceutical manufacturing
- Water and wastewater treatment
- Power generation
- Oil and gas
- Pulp and paper
- Architectural and construction
How to Choose the Right Stainless Steel 304 Flanges Supplier?
Keep the following things in mind while choosing the right SS 304 flanges supplier.
Supplier Selection Criteria
Begin with inventory availability of multiple flange types, sizes, and pressure classes. A dependable supplier carries WNRF, SORF, and blind flanges in Class 150 and Class 300 as stock for standard NPS sizes. For large bore or high-pressure classes, check that the supplier can source or manufacture to order within your project lead time. If your project requires international specifications, it’s worth verifying experience with both ASME and DIN standards.
Technical Considerations
Ask for material test certificates for chemical composition and mechanical properties as per ASTM A182 and ASME SA182. Verify carbon content is within 304 limits (max 0.08%) for welded assemblies vs. supplied as 304L without documentation. Check your pressure class and NPS against the flange dimensions. For process flanges, check facing type (RF, FF, or RTJ) matches your gasket and bolting specification.
Quality and Certification Check
EN 10204 / 3.1 mill test certificates with heat number traceability are the baseline. For critical process flanges, it is advisable to ask for PMI (positive material identification) test reports on finished flanges to verify material identity. ISO 9001 certification is the minimum standard for suppliers. Check the CE marking and the compliance with EN 1092-1 in case of PED applications. Material shall be tested in accordance with ASME Section II Part A material specifications for ASME code applications.
Procurement Tips for Bulk Orders
SS 304 prices are closely linked to LME nickel. Schedule your procurement and lock-in rates for long-term projects in times of market stability. Bulk purchase of standard sizes can be done to ensure supply continuity and cost reduction. Request samples and dimensional inspection reports before approving a full production run. Confirm delivery timelines in writing. Allow extra lead time for machining, plus standard forging lead times for flanges with special facing or custom bore.
Stainless Steel 304 Flanges Suppliers
Stainless Steel 304 Flanges FAQ's
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