Stainless Steel 254SMO application

Introduction

254SMO (UNS S31254, ASTM F44, 1.4547) is a so-called super austenitic stainless steel. By increasing the molybdenum content to 6%, it achieves a pitting resistance equivalent number (PREN) > 43, which is similar to that of a super duplex stainless steel (SDSS). When comparing 254SMO to super duplex stainless steels, it is non-magnetic, potentially more straightforward to weld and has a wider operating temperature range. However, it is considerably more expensive due to its greater nickel and molybdenum content and has a significantly lower strength. Therefore, it will mostly be used in applications where the use of super duplex stainless steels is limited. This could include applications at lower temperatures (>-50degC) where the impact strength of SDSS drops, or at higher temperatures (>-250degC) where there is a risk of forming deleterious phases if exposed for extended periods.

Alloy 254 SMO is a very high end, molybdenum and nitrogen alloyed super austenitic stainless steel with low carbon content. It demonstrates outstanding resistance to pitting, crevice corrosion stress cracking, and corrosion fatigue uniform corrosion. Alloy 254 SMO is substantially stronger than the common austenitic grades, with strength nearly twice that of 300 series stainless steel. It is also characterized by high ductility and impact strength. With high levels of chromium, molybdenum, and nitrogen, Alloy 254 SMO is frequently used in high chloride environments, such as brackish water, seawater, pulp mill bleach plants, and other chloride process streams. In some applications it has even been found to be a more cost effective substitute for high nickel and titanium alloys.

Stainless steel 254SMO ( UNS S31254 ) is a very high end austenitic stainless steel. It is designed with a combination of impact toughness resistance to chloride stress corrosion cracking, and pitting and crevice corrosion with strength that is twice that of the stainless steel 300 series. For certain applications, stainless steel 254SMO ( 1.4547 ) has been reported to be a cost-effective substitute for high nickel and titanium alloys. It is known to possess excellent workability as well.

254 SMO Chemical Composition

SMO 254 Characteristics

These are the products that perform well in halide solutions with chloride and bromide ions present. The SMO 254 grade demonstrates the impact of local corrosion caused by pitting, crevices, and tension. SMO 254 is a low-carbon element material. Because of the low carbon content, there is a reduced chance of carbide precipitation during heat application during welding activity.

MACHINABILITY

Due to the exceptionally high work hardening rate and lack of sulfur content, stainless steel grade 254 SMO™ is quite difficult to mill; however, sharp tools, powerful machine machines, positive feeds, and a substantial amount of lubrication, and slow speeds tend to offer decent machining results.

WELDING

Welding stainless steel grade 254 SMO necessitates the use of filler material, which results in inferior tensile qualities. AWS A5.14 ERNiCrMo-3 and alloy 625 are approved as filler metals. The electrodes used in the process must comply with AWS A5.11 ENiCrMo-12.

ANNEALING

The annealing temperature for this material should be 1149-1204°C (2100-2200°F), followed by a water quench.

WORKING IN EXTREME CONDITIONS

Forging, upsetting, and other operations using this material can be carried out at temperatures ranging from 982 to 1149°C (1800 to 2100°F). Temperatures above this range are not recommended since they will cause scaling and reduce the material’s workability. It is recommended to undertake post-process annealing to regain maximal corrosion resistance.

WORKING IN THE COLD

Cold working can be done using any of the usual methods; however, the procedure will be difficult due to the high work hardening rate. As a result, the material will have greater strength and toughness.

HARDENING

Heat treatment does not affect stainless steel grade 254 SMO.  Only cold reduction allows for hardening.

Stainless Steel 254SMO application

254 SMO offer numerous advantages over traditional metal piping options, efficient to their superior corrosion resistance and strength at high temperatures. These features make them well-suited for a wide range of industries, including chemical processing plants, oil refineries, power generation plants, and marine engineering projects where exposure to highly corrosive substances is common place. Stainless steel 254 SMO exhibit unmatched strength, which significantly outperforms conventional stainless steel pipes, ensuring a longer lifespan for various applications. Some common industries employing these pipes include oil and gas, petrochemical, and marine, where they are subject to harsh environmental conditions and extreme temperatures.

Gas and Oil Industry

254 SMO is a type of stainless steel used in the oil and gas industry. It has many distinct features that make it ideal for use in these hazardous environments, such as its high corrosion resistance even under tough conditions; its ability to resist pitting, crevice corrosion, and stress cracking; and its extraordinary strength compared to other metals. Furthermore, it is extremely malleable, fabricating the tubing into various shapes, sizes and lengths without compromising strength or longevity. The material’s unique combination of characteristics makes it an excellent choice for connecting pipes within this sector – ensuring safe operations throughout the life cycle.

Marine Industry

254 SMO is a type of stainless steel pipe used in the marine industry. It’s composed of high alloy duplex stainless steel containing roughly 25% chromium, 4% molybdenum, and 7% nickel for superior corrosion resistance. It is extremely resistant to pitting corrosion, especially in seawater environments, making it ideal for use on boats, ships, yachts, and other marine vessels exposed to saltwater conditions. 254 SMO  provides excellent weldability due to its austenitic-ferritic nature and being mechanically strong, making it perfect for use in any boat design or powerboat project with long runs of tubing required.

Chemical Industry

254 SMO is an austenitic stainless steel alloy most commonly used in the chemical industry. This material offers corrosion resistance, strength and flexibility, making it suitable for many high-pressure or corrosive media applications. It features a high molybdenum content and good heat and oxidation resistance, making it highly corrosion-resistant to sulfuric acid concentrations up to 50%. Compared to other standard alloys, such as 304L stainless steel, SMO 254 also exhibits superior strength at elevated temperatures. Due to its highly corrosion-resistant nature and excellent mechanical properties, 254 SMO is frequently used in chemical processing operations. Its composition allows it to stand up against harsh chemicals and extreme conditions – making this alloy one of the most popular choices for use in the chemical industry.

Power Generation

The power generation industry requires materials resistant to high temperatures and pressure. DUE TO ITS EXCEPTIONAL STRENGTH AND CORROSION RESISTANCE PROPERTIES, 254 SMO is used in steam generators, evaporators, and heat exchangers.

Food Processing Industry

254 SMO is a popular choice for the food processing industry due to its corrosion resistance and hygienic properties. It is used in processing equipment for acidic food, such as citrus and tomato fruits, and other food processing applications.

In conclusion, SMO 254 pipes have emerged as a popular choice for marine applications thanks to their excellent properties, such as high corrosion resistance, strength, and weldability. Their benefits extend beyond marine applications and can be used in various other industries requiring high corrosion resistance materials. With proper maintenance, SMO 254 can last for many years, making it a sound investment for anyone looking for long-lasting, reliable piping systems.