What is ASTM A182 F321 material?
ASTM A182 F321 / 321H stainless steel flanges are forged austenitic stainless steel grade that belongs to the 321 stainless steel (SS 321) family. It is stabilized with titanium (Ti) to prevent intergranular corrosion, especially in high-temperature environments.
Chemical Composition of ASTM A182 F321\321H
| CHEMICAL | LIMITS | C | Mn | P | S | Si | Ni | Cr | Mo | N | Ti |
| ASTM A182 F321 | MIN | 9.00 | 17.00 | 0.10 | 5(C+N) | ||||||
| MAX | 0.08 | 2.00 | 0.05 | 0.03 | 1.00 | 12.00 | 19.00 | 0.70 | |||
| ASTM A182 F321H | MIN | 0.04 | 9.00 | 17.00 | 4（C+N) | ||||||
| MAX | 0.10 | 2.00 | 0.045 | 0.030 | 1.00 | 12.00 | 19.00 | 0.7 |
Key Properties of ASTM A182 F321\321H
| Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
| Rockwell B (HR B) max | Brinell (HB) max | ||||
| 321 | 515 | 205 | 40 | 95 | 217 |
| 321H | 515 | 205 | 40 | 95 | 217 |
| Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/kg.K) | Electrical Resistivity (nΩ.m) | |||
| 0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
| 321 | 8027 | 193 | 16.6 | 17.2 | 18.6 | 16.1 | 22.2 | 500 | 720 |
High-Temperature Resistance: Can withstand 450–800°C (840–1470°F) without carbide precipitation.
Corrosion Resistance: Excellent resistance to oxidation and intergranular corrosion (prevents carbide formation at grain boundaries).
Good Weldability: Can be welded using standard techniques without post-weld heat treatment.
Creep and Stress Rupture Resistance: Better than SS 304 in elevated temperature conditions.
Applications of ASTM A182 F321\321H
Flanges, fittings, and valves in high-temperature piping systems
Exhaust manifolds and turbine components in aerospace and automotive industries
Heat exchangers and pressure vessels in chemical and petrochemical industries
Furnace parts and superheater tubes in power plants
What does A182 mean?
ASTM A182 is a standard specification issued by ASTM International for forged or rolled alloy and stainless steel pipe flanges, fittings, valves, and parts intended for high-temperature and high-pressure applications.
ASTM → American Society for Testing and Materials (now ASTM International)
A → Indicates ferrous materials (iron-based alloys, including steel).
182 → The specific standard number for forged or rolled alloy and stainless steel materials used in high-temperature service.
What is the difference between F321 and F321H?
ASTM A182 F321 and F321H are both high-temperature stabilized austenitic stainless steels based on SS 321. The main difference between them lies in their carbon content, which affects their performance at elevated temperatures.
| Element | ASTM A182 F321 (%) | ASTM A182 F321H (%) |
| Carbon (C) | ≤ 0.08 | 0.04 – 0.10 (higher carbon) |
Performance Differences
| Property | F321 | F321H |
| High-Temperature Resistance | Good for 450–800°C (840–1470°F) | Better creep resistance at high temperatures |
| Corrosion Resistance | Excellent intergranular corrosion resistance | Similar corrosion resistance but better for prolonged high-temperature use |
| Weldability | Good | Good, but post-weld heat treatment may be needed for thick sections |
| Creep and Stress Rupture Strength | Moderate | Higher than F321 |
Key Difference: F321H performs better in prolonged high-temperature environments, such as boilers and heat exchangers.
Application Suitability
| Application | F321 | F321H |
| Exhaust Systems | ✅ | ✅ |
| Heat Exchangers | ✅ | ✅ (Preferred for high temperatures) |
| Steam Boilers / Superheaters | ❌ | ✅ (Better performance) |
| Pressure Vessels | ✅ | ✅ |
| Chemical Processing Equipment | ✅ | ✅ |
Stainless Steel Flanges Specification
| Sealing Face | RF, FF, FTJ |
| Size Range | 1/2″ – 24″ / DN15 – DN600 |
| Pressure Rating | Class 150, 300, 600, 900, 1500, 2500lb |
| Standard | ANSI / ASME B16.5, EN1092-1 |
| ASTM A182 Flange Types | Welding Neck Flange, Slip On Flange, Socket Weld Flange, Lap Joint Flange, Threaded Flange, Blind Flange, |
| Stainless Steel | ASTM A182 F304/304L/304H, 316/316L, 310S, 317,321,321H,347,904L |
Equivalent Standards
| Standard | Equivalent Grade |
| UNS | S32100 (F321), S32109 (F321H) |
| EN/DIN | 1.4541 (F321), 1.4878 (F321H) |
| JIS | SUS 321 / SUS 321H |
Corrosion Resistance:
Stainless Steel 321 offers exceptional corrosion resistance, especially in environments where exposure to high temperatures and corrosive substances is common.
High Temperature Resistance:
The titanium stabilization in Stainless Steel 321 provides improved high-temperature strength and resistance to intergranular corrosion, making these flanges suitable for applications involving elevated temperatures.
Weldability:
The titanium content helps prevent the formation of chromium carbide precipitation at grain boundaries during welding, reducing the risk of intergranular corrosion.
Types of Flanges:
Stainless Steel 321 Flanges come in various types, including slip-on flanges, Weld Neck Flanges, Socket Weld Flange, threaded flanges, and Blind Flange. The choice of flange type depends on the specific requirements of the piping system.
Standards and Specifications:
Stainless Steel 321 Flanges are manufactured according to international standards such as ASTM A182/A240 for material specifications and ASME B16.5 for dimensional standards.
Types of Stainless Steel Flange
The weld neck flange has a structure with a neck and a round tube transition, which can be butt weld to the pipe to form a firm pipe connection point.
Socket Weld Flange designed in accordance with ASME B16.5 standards, is a high-integrity flange used for creating a secure pipe connection in high-pressure systems.
The threaded flange uses a screw thread to connect the flange onto pipe. A male thread is cut onto a pipe end while a female thread is cut into the bore of the flange. The male threaded pipe is then screwed into the female threaded flange.
Threaded flange Dimensions & Weight
The main structural feature of the lap joint flange is the loose connection. It consists of a flange body, a flange nipple and connecting bolts. The flange body and the flange nipple are loose fitting, and this structure allows the pipeline to expand and contract freely within a certain range.
ASTM A182 blind flanges help to terminate the ends of piping systems, and the main purpose of using blind flanges is to close off the unused portion of pipe or nozzle.
Blind flange Dimensions & Weight Chart
Slip on flange is mainly used for low-pressure fluids that have minimal risk of leakage.
What is the difference between ss321 and 347 stainless steel?
SS 321 vs. SS 347 Stainless Steel: Key Differences
Both SS 321 and SS 347 are stabilized austenitic stainless steels with similar corrosion resistance and mechanical properties, but they differ in their stabilizing elements and specific applications.
Stabilizing Elements
SS 321 is stabilized with Titanium (Ti)
SS 347 is stabilized with Columbium/Niobium (Cb/Nb)
These stabilizers prevent intergranular corrosion by avoiding carbide precipitation at high temperatures.
Performance Differences
| Property | SS 321 | SS 347 |
| High-Temperature Resistance | Good | Slightly better |
| Corrosion Resistance | Similar to SS 347 | Slightly better in strong oxidizing conditions |
| Weldability | Good | Good, but better for welding heavy sections |
| Oxidation Resistance | Up to 900°C (1650°F) | Up to 950°C (1750°F) |
| Creep Resistance | Moderate | Better than SS 321 |
When to Choose SS 321 vs. SS 347?
Choose SS 321 if the application involves cyclic temperature changes and resistance to thermal fatigue is important.
Choose SS 347 if prolonged high-temperature exposure and better weldability.
Applications of ASTM A182 F321 / 321H Flanges
Petrochemical and Refinery Piping
Heat Exchangers and Pressure Vessels
Aircraft Exhaust Systems
Steam Boilers and Superheaters
Chemical and Power Plant Equipment
You can get an offer for products in below material forms:
-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)
-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )
-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)
-Round bar , Billet (ASTM A276, ASTM A479)
– Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)
-Bolting, Nuts（ASTM A193, A194, A320）
ASTM A182 F321 / 321H Stainless Steel Flanges Exported Countries
We Export ASTM A182 F321 / 321H Stainless Steel Flanges to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan, Europe, Africa, Asia, North America, South America, Middle East.etc
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