Stainless Steel SMO 254 Flanges

SMO 254 flanges are a high-alloy austenitic grade for aggressive corrosive environments. They are produced under UNS S31254 and ASTM A182 F44 and have much higher amounts of molybdenum and nitrogen than standard stainless grades. This translates directly into better pitting and crevice corrosion resistance. Industries handling chloride-rich or acidic media rely on these flanges where conventional stainless steel fails. Stainless Steel SMO 254 Flanges are available across all standard flange types and pressure classes under ASME B16.5 and B16.47.

Price of Stainless Steel SMO 254 Flanges

SMO 254 flange pricing reflects the high molybdenum and nitrogen content in the alloy. Costs are notably higher than standard austenitic grades across all sizes.

Approx Price Range

Stainless Steel SMO 254 Flanges are priced between ₹650/piece to ₹3,654/piece for standard sizes and configurations. Speciality alloy content makes this grade more expensive than most austenitic stainless grades.

Price Per Unit / Kg

On a per-kg basis, UNS S31254 flanges generally cost about ₹130. Higher pressure classes mean larger flanges, which will cost more per unit since they contain more material and require more machining.

Factors Affecting Price

Molybdenum content in SMO 254 flanges keeps raw material costs high. Flange type, pressure class, custom bore dimensions, and third-party testing all add to the final price. Overseas Stainless Steel SMO 254 Flanges suppliers may include import and freight charges. Bulk orders generally bring the per-unit cost down.

Types of Stainless Steel SMO 254 Flanges

254 SMO flanges type selection depends on system pressure, connection method, and whether the joint needs to be regularly dismantled.

They are manufactured in the following types:

Weld Neck Flanges
Slip-On Flanges
Blind Flanges
Socket Weld Flanges
Lap Joint Flanges
Threaded Flanges
Orifice Flanges
Ring Type Joint (RTJ) Flanges

Specifications of Stainless Steel SMO 254 Flanges

The table below covers the core specification parameters for SMO 254 flanges across standard manufacturing and dimensional references.

Parameter	Details
Grade	SMO 254 / UNS S31254 / ASTM A182 F44
Standard	ASTM A182, ASME B16.5, ASME B16.47, MSS SP-44
Pressure Class	150# to 2500#
Size Range	½" to 60"
Facing Type	Raised Face (RF), Flat Face (FF), Ring Type Joint (RTJ)
Manufacturing Process	Forged, Plate Cut, Cast

Chemical Properties of Stainless Steel SMO 254 Flanges

The chemical composition of ASTM A182 F44 UNS S31254 is controlled tightly, particularly for molybdenum and nitrogen, which drive corrosion performance.

Element	Composition (%)
Carbon (C)	Max 0.020
Chromium (Cr)	19.5 – 20.5
Nickel (Ni)	17.5 – 18.5
Molybdenum (Mo)	6.0 – 6.5
Nitrogen (N)	0.18 – 0.22
Copper (Cu)	0.50 – 1.00
Manganese (Mn)	Max 1.00
Silicon (Si)	Max 0.80
Phosphorus (P)	Max 0.030
Sulfur (S)	Max 0.010
Iron (Fe)	Balance

The combination of high Mo and N content gives UNS S31254 flanges a PREN above 42, one of the highest among standard austenitic grades.

Mechanical Properties of Stainless Steel SMO 254 Flanges

These values apply to forged and plate-cut SMO 254 flanges produced per ASTM A182 F44.

Property	Value
Tensile Strength	Min 650 MPa
Yield Strength (0.2% offset)	Min 300 MPa
Elongation	Min 35%
Hardness (Brinell)	Max 223 HB
Hardness (Rockwell B)	Max 96 HRB

Physical Properties of Stainless Steel SMO 254 Flanges

Physical property data for UNS S31254 flanges relevant to piping design and material selection.

Property	Value
Density	8.0 g/cm³
Melting Point	1320 – 1390°C
Thermal Conductivity	13 W/m·K
Electrical Resistivity	0.85 µΩ·m
Magnetic Permeability	Non-magnetic
Modulus of Elasticity	195 GPa

Dimension Chart of Stainless Steel SMO 254 Flanges

Standard dimensions for 254 SMO flanges follow ASME B16.5 for NPS ½" to 24" and ASME B16.47 for larger sizes.

NPS (inches)	OD (mm)	Bolt Circle (mm)	No. of Bolts	Bolt Hole Dia (mm)
½"	88.9	60.3	4	15.7
1"	107.9	79.4	4	15.7
2"	152.4	120.6	4	19.0
4"	228.6	190.5	8	19.0
6"	279.4	241.3	8	22.4
8"	342.9	298.4	8	22.4
10"	406.4	362.0	12	25.4
12"	482.6	431.8	12	25.4

Class 150 dimensions per ASME B16.5.

Size Chart of Stainless Steel SMO 254 Flanges

The table below covers the available size range for SMO 254 flanges, along with stock availability and order type by size category.

Size Range (NPS)	Availability	Supply Type	Notes
½" to 2"	Readily available	From stock	Standard bore and wall thickness
2½" to 12"	Readily available	From stock	Bore varies by pipe schedule
14" to 24"	Generally available	From stock	Confirm with the supplier
26" to 48"	Limited	Made to order	Longer lead times apply
50" to 60"	On request	Made to order	Extended lead times

Wall thickness and bore dimensions across all sizes vary by pipe schedule and pressure class assigned at the time of order.

Pressure Rating Chart of Stainless Steel SMO 254 Flanges

Pressure ratings below are for UNS S31254 flanges at 38°C. Ratings reduce as operating temperature increases; always verify against ASME B16.5 tables for actual service conditions.

Class	Pressure Rating at 38°C
150	19.6 bar (285 psi)
300	51.1 bar (740 psi)
600	102.1 bar (1480 psi)
900	153.2 bar (2220 psi)
1500	255.3 bar (3705 psi)
2500	425.5 bar (6170 psi)

Key Features of Stainless Steel SMO 254 Flanges

SMO 254 flanges are built for high-chloride and aggressive acid environments where standard stainless grades fall short.

PREN above 42, suitable for seawater and high-chloride service
Resistant to pitting, crevice corrosion, and uniform corrosion in acids
Non-magnetic
Compliant with ASTM A182 F44, designated under UNS S31254
Available in all standard flange types and pressure classes
Resistant to sulfuric and phosphoric acid environments
Compatible with standard pipe facing types and gasket materials

Applications of Stainless Steel SMO 254 Flanges

Stainless Steel SMO 254 Flanges are used across several demanding industries where standard stainless grades are not sufficient.

Desalination plants
Chemical processing facilities
Offshore and marine structures
Pulp and paper bleaching systems
Pharmaceutical manufacturing
Flue gas desulfurization systems
Oil and gas production and processing

The corrosion resistance of ASTM A182 F44 UNS S31254 is what drives specifications across all of these sectors.

How to Choose the Right Stainless Steel SMO 254 Flanges Supplier?

SMO 254 is a speciality grade. Not every supplier stocks it consistently, so verifying availability and certifications early saves time later.

Supplier Selection Criteria

Focus on suppliers who specialise in or regularly stock SMO 254 flanges rather than those who carry it as a secondary line. Ask for MTCs from recent production batches and verify that the material is properly certified to ASTM A182 F44. Check lead times for both standard and large sizes before committing.

Technical Considerations

Verify chemical composition against UNS S31254 specifications, on molybdenum and nitrogen in particular, as these are the elements affecting corrosion resistance. Verify flange type, pressure class, and face. If the application is for acid service or offshore, check that the supplier can support additional testing requirements.

Quality & Certification Check

The Stainless Steel SMO 254 Flanges shall be supplied by reliable suppliers with certification of EN 10204 3.1 or 3.2. European supply is relevant for PED compliance. For critical projects, third-party inspection from agencies like Bureau Veritas, SGS, or Lloyd’s is preferable.

Procurement Tips for Bulk Orders

For large orders, confirm the supplier's mill source and ask for composition data from previous production runs. Negotiate on the delivery schedule as much as on price since delays on speciality alloy flanges can affect project timelines. Consolidating flange types into a single order typically results in better pricing from most UNS S31254 flange suppliers.