SMO 254 Stainless Steel Flange

SMO 254 Flanges are flange fittings made from an austenitic stainless steel alloy called SMO 254. This alloy contains higher levels of molybdenum, chromium, and nitrogen, providing exceptional resistance to corrosion, especially in highly acidic environments. SMO 254 Flanges are known for their excellent strength, impact resistance & low maintenance requirements. These flanges are widely used in marine, offshore, chemical, and desalination industries

What is SMO 254 stainless steel?

SMO 254 stainless steel (also known as Alloy 254 SMO) is a highly corrosion-resistant, super-austenitic stainless steel designed for use in aggressive environments. It is known for its excellent resistance to pitting, crevice corrosion, and stress corrosion cracking, particularly in environments with chlorides and other corrosive substances.

High Corrosion Resistance:

254 SMO is especially resistant to corrosion in environments that contain chlorides, such as seawater, chemical processing environments, and pulp & paper industries. It has a superior resistance to pitting and crevice corrosion compared to standard austenitic stainless steels (like 316L).

Excellent Stress Corrosion Cracking Resistance:

It is highly resistant to stress corrosion cracking (SCC), which is a common issue in chloride-rich environments.

High Strength and Toughness:

It maintains its mechanical properties at both high and low temperatures. It has a high yield strength and good toughness, which makes it suitable for demanding structural applications.

Good Weldability:

254 SMO has good weldability, and it can be welded using conventional methods for stainless steel welding. Special care should be taken to avoid overheating during welding.

UNS S31254 Duplex Stainless Steel F44 Flanges Specification

Specifications : ASTM A182 / ASME SA182

Dimensions : ANSI/ASME B16.5

Standard : ANSI Flanges, ASME Flanges,

Size : 1/8″ NB TO 24″ NB

Class / Pressure : 150#, 300#, 600#, 900#, 1500#, 2500#, PN6, PN10, PN16, PN25, PN40, PN64 etc.

Flange Face Type : Flate Face (FF), Raised Face (RF), Ring Type Joint (RTJ)

Grade : ASTM A182 Gr F44 UNS S31254

Manufacturing Standards:

ASTM A182 F44 flanges are manufactured according to the standards outlined in ASTM A182, which specifies the requirements for forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves.

Testing and Certification:

ASTM A182 F44 flanges undergo rigorous testing to ensure they meet the specified mechanical and chemical properties. Common tests include hydrostatic testing, tensile testing, and non-destructive testing.

Flanges meeting the requirements of ASTM A182 F44 are typically supplied with relevant documentation and certifications.

ASTM A182 Duplex F44 UNS S31254 Flanges Chemical Composition

ASTM A182 F44 UNS S31254 Flanges Mechanical Properties

What is material 254 SMO equivalent to?

Equivalent or Similar Alloys

Some materials are considered alternatives or equivalents to 254 SMO based on similar chemical composition and corrosion resistance properties:

What is the difference between SMO 254 and ss316?

SMO 254 is a “super austenitic” stainless steel with significantly higher corrosion resistance than SS316, especially in chloride-rich environments, while SS316 is a standard “marine grade” stainless steel with good, but not as exceptional, corrosion resistance. 

Corrosion Resistance: 

SMO 254:

Exhibits exceptional resistance to pitting, crevice, and stress corrosion cracking, even in harsh environments like seawater and chemical processing. It achieves this through its high levels of chromium, molybdenum, and nitrogen. 

SS316:

Offers good corrosion resistance, particularly in chloride environments, but is not as resistant to pitting and crevice corrosion as SMO 254. 

Composition:

SMO 254:

Contains a higher percentage of molybdenum (around 6%) and nitrogen, along with chromium and nickel, to enhance its corrosion resistance. 

SS316:

Contains molybdenum (around 2-3%), chromium, and nickel, with lower percentages compared to SMO 254. 

Applications:

SMO 254:

Commonly used in applications requiring extreme corrosion resistance, such as seawater filtration, chemical processing equipment, and offshore oil and gas platforms. 

SS316:

Suitable for a wide range of industrial applications where good corrosion resistance is needed, such as food processing, chemical processing, and marine applications. 

Machinability and Weldability:

SMO 254:

Can be more difficult to machine due to its high work-hardening rate and lack of sulfur content, and requires specific filler materials for welding.

SS316:

Offers good machinability and weldability, making it a more versatile option for various applications. 

Forged Flange Types

	Blind Flange A blind flange is a flange without a hole in the middle. It looks similar to a common flange and has bolt holes around it. It is like a sealed “lid” used to close the end of a pipe or isolate a part of a pipe system.
	Lap Joint Flange The main structural feature of the A182 lap joint flange is the loose connection. It consists of a flange body, a flange nipple and connecting bolts.
	Slip On Flange Slip on flange is to insert the pipe into the inner hole of the flange, and then perform fillet welding on the outside of the flange and the pipe. Its structure is relatively simple, easy to manufacture and low cost.
	Socket Weld Flange One end of the socket flange is the socket, and the other end is the flange. The socket part is used to insert the matching pipe, and then sealed by welding or sealing materials.
	Threaded Flange The threaded flange has threads processed on the inner hole of the flange, which is connected to the pipe with external threads through the threads. There are also bolt holes around the flange, which can be used for further connection and fixation with other flanges or equipment.
	Weld Neck Flange Weld Neck Flange is to connect the flange and the pipe through butt welding. The neck of the flange matches the outer diameter of the pipe. When connecting, the butt joint of the pipe and the flange should be grooved to ensure the welding quality.

What is the difference between 254 SMO and Al 6XN?

Corrosion Resistance

Both alloys are excellent for marine, chemical processing, and high-chloride environments, but there are differences:

Pitting & Crevice Corrosion Resistance (PREN Value)

254 SMO: PREN = ~42.5

AL-6XN: PREN = ~45
Higher PREN = better resistance to localized corrosion (pitting & crevice corrosion).

Chloride Resistance

AL-6XN performs slightly better due to its higher Nickel and Molybdenum content.

Both can withstand exposure to seawater, but AL-6XN may offer slightly better performance in high-salinity or brine conditions.

Weldability and Fabrication

AL-6XN is easier to weld and fabricate due to its higher Nickel and Manganese content.

254 SMO requires more careful welding because of its slightly higher Chromium and Nitrogen content, which can make it more prone to cracking if not handled properly.

Cost and Availability

AL-6XN is generally more cost-effective than 254 SMO due to lower alloying costs.

254 SMO is often more expensive due to its higher Chromium content and sometimes limited availability.

Applications

AL-6XN is preferred for food processing and pharmaceuticals because it is easier to weld and fabricate.

254 SMO is used more in aggressive marine and chemical environments due to its higher yield strength.

Final Verdict:

AL-6XN is a more cost-effective and weldable alternative to 254 SMO, with better resistance to SCC and slightly better pitting resistance.

254 SMO remains the go-to choice for extreme environments requiring higher strength and oxidation resistance.

ASTM A182 F44 Flange Application

– Oil and Gas Industries

– Food Processing Industries

– Equipments

– Pipeline

– Power Industries

– Ship Building Industries

– Paper Industries

– Cement Industries

– Chemical Industries

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）

SMO 254 Stainless Steel Flange Exported Countries

We Export SMO 254 Stainless Steel Flange 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