Views: 2 Author: Site Editor Publish Time: 2026-10-13 Origin: Site
In July 2026, 194 pieces of ASTM A182 F44 threaded flanges were completed and delivered on schedule to a long-term customer in Singapore. The order covers sizes from 1/2 inch to 3 inch. Pressure ratings range from Class 150 to Class 1500. Sealing faces include RF and RTJ. For buyers in marine engineering and chemical processing, the choice of F44 flange material is a rational decision against highly corrosive service conditions.
ASTM A182 F44 is known asSMO254 (UNS S31254). It is a 6Mo super austenitic stainless steel. Its core advantage is high molybdenum content for corrosion resistance. Compared with conventional 316L stainless steel, SMO254 has a Pitting Resistance Equivalent Number (PREN) typically above 40. This means a step-change improvement in pitting and crevice corrosion resistance in high-chloride environments.
The table below compares key composition differences between SMO254 and common stainless steels.
材料牌号 | 铬 (Cr) | 镍 (Ni) | 钼 (Mo) | 氮 (N) | PREN* |
316L | 16-18% | 10-14% | 2-3% | — | ~25 |
904L | 19-23% | 23-28% | 4-5% | — | ~34 |
SMO254 (F44) | 19.5-20.5% | 17.5-18.5% | 6.0-6.5% | 0.18-0.22% | ≥40 |
PREN = Cr% + 3.3 × Mo% + 16 × N%. Higher values mean stronger pitting resistance.
SMO254 molybdenum content is more than twice that of 316L. Nitrogen is added. These features give it far better corrosion resistance than conventional austenitic stainless steels in chloride media. This matters for marine engineering, seawater desalination, and chemical processing projects in Singapore and Southeast Asia. In these services, equipment contacts chloride media for long periods. Ordinary stainless steel can suffer stress corrosion cracking. The high-alloy formula of SMO254 resists such attack. This means longer maintenance intervals and lower unplanned downtime risk.
These flanges were manufactured strictly to ASTM A182. In forging and machining, the critical process control points for super austenitic stainless steel are heat working temperature and cooling rate. SMO254 tends to precipitate intermetallic phases such as sigma phase at high temperatures. This severely harms toughness and corrosion resistance. Therefore, solution treatment and rapid cooling after forging are required. This ensures alloying elements fully dissolve in the austenitic matrix.
For welding, SMO254 has good weldability. Nickel-based filler metals such as ERNiCrMo-3 are usually recommended. Their molybdenum content is higher than the base metal. This compensates for possible molybdenum segregation during welding, which can reduce corrosion resistance. For RTJ ring joint face flanges, seal groove dimensional accuracy and surface roughness control are also critical. These directly determine metal seal reliability under high pressure.
For pipe components exported to Singapore, completeness of quality certificates and traceability of inspection data are core to customer acceptance. Two key inspections were performed before shipment.
QC staff measured outer diameter, bolt hole center distance, bolt hole diameter, flange thickness, sealing face dimensions, and thread accuracy item by item per ASME B16.5. For NPTF threads, taper and thread form were checked with dedicated thread gauges using GO and NO-GO detection. This ensures smooth field assembly and reliable sealing.
A portable spectrometer was used for 100% piece-by-piece scanning of flange bodies. It verified that chromium, nickel, molybdenum, nitrogen, and other major alloying elements fall within the ASTM A182 F44 (SMO254) standard range. PMI effectively distinguishes SMO254 from ordinary 316L or 904L. It prevents material mixing risk. Every flange sent to the customer site is confirmed to be the correct material.
Only after both dimensional and material inspections pass do products enter packaging and shipping. This inspection flow has become our standard practice for exported corrosion-resistant alloy flanges.
This order totals 194 pieces. It covers threaded flanges and socket weld flanges. Specific sizes and quantities are below.
ITEM | DESCRIPTION | QTY | UNIT |
THREADED RAISED FACE REDUCING FLANGE | |||
MATERIAL: ASTM A182 F44 | |||
1 | 1" 300# RF X 1/2" NPTF | 18 | PCS |
2 | 1-1/2" 150# RF X 1/2" NPTF | 8 | PCS |
3 | 2" 150# RF X 1/2" NPTF | 90 | PCS |
4 | 2" 300# RF X 1/2" NPTF | 22 | PCS |
5 | 3" 300# RF X 1/2" NPTF | 20 | PCS |
THREADED RING TYPE JOINT REDUCING FLANGE | |||
MATERIAL: ASTM A182 F44 | |||
6 | 1-1/2" 1500# RTJ X 1/2" NPTF | 16 | PCS |
7 | 1-1/2" 2500# RTJ X 1/2" NPTF | 20 | PCS |
TOTAL | 194 | PCS |
Send Your Drawing for a Fast Quote
Singapore is a major hub for global marine engineering and petrochemicals. It has strict requirements for pipe component certification and quality documents. The long-term customer requested complete material certificates and traceability documents in early communication. This ensures products meet project specifications. After receiving the inquiry, we checked thread type (NPTF) and sealing face rating item by item with the customer. We confirmed delivery time and packaging requirements. Production was completed and shipped as planned.
A: ASTM A182 F44 is a wrought austenitic stainless steel forging grade. It is commonly known as SMO254 or UNS S31254. It is a 6Mo super austenitic stainless steel with PREN ≥40.
A: SMO254 contains about 6.0–6.5% molybdenum and 0.18–0.22% nitrogen. 316L contains only 2–3% molybdenum and no nitrogen. SMO254 has much higher pitting and crevice corrosion resistance in chloride environments.
A: RF (raised face) and RTJ (ring type joint) are both available. RTJ is suitable for high-pressure service such as Class 1500 and 2500.
A: We perform 100% PMI spectral inspection on every flange body. This verifies Cr, Ni, Mo, and N content against the ASTM A182 F44 standard.
A: Lead time depends on quantity and specifications. Send your drawing and working conditions. We will respond with technical support and a quotation within 24 hours.
If you are sourcing ASTM A182 F44 (SMO254) flanges or other corrosion-resistant alloy pipe components for marine engineering, seawater desalination, or chemical plants, contact us through the inquiry form on our website or by direct email. Provide drawings and working parameters. We will give technical support and quotation feedback within 24 hours.
