254 SMO pipes and tubes are made with a very high end, molybdenum and nitrogen alloyed super austenitic stainless steel which contains low carbon content. SMO 254 pipes and tubes (UNS S31254) are the product of austenitic stainless steel developed for maximum resistance to pitting and crevice corrosion.
SMO 254 pipes and tubes are practically stronger than regular austenitic grade but are also known for their high ductility and impact strength. These pipes and tubes are cost effective options for high nickel and titanium alloy. Because of its austenitic microstructure, 254 SMO stainless steel pipes and tubes have very good impact strength, at both room temperature and at cryogenic temperatures.
254 SMO pipe or S31254 are created such as ERW (Electric Resistance Welded), seamless and EFW (Electric Fusion Welding) pipes and tubes with different forms like round, square, rectangle, etc. having specific ends as a plain end, bevel end, and threaded end with normal thickness of different schedule ranging from SCH 5 to SCH XXS
Stainless steel SMO 254 Seamless Pipe : ASTM/ASME SA 312/ A 312
Stainless steel SMO 254 Seamless tube : ASTM/ASME SA 213/A 213
Stainless steel SMO 254 ERW Pipe : ASTM/ASME SA 312/ A 312
Stainless steel SMO 254 ERW Tube : ASTM/ASME SA 249/ A 249
Various processes are used to manufacture 254 SMO pipe and tubes such as cold pilgering process, extrusion process, tube mill process as well as the piercing process which is then followed by heat treatment and mechanical testing.
Fabrication and Heat Treatment
Grade 254 SMO pipe and tubes can be easily fabricated by hot forming or cold forming processes. In the hot forming process, the complete workpiece is exposed to a sufficiently high temperature. Hot forming should be worked in the temperature range of 1200°C-950°C. In the case of partial heating, or cooling that is too slow, solution annealing is to be done after hot working. The temperature is to be maintained at least 1150°C to eliminate residual intermetallic phases from the working.
Alloy 254 SMO pipes and tubes made with UNS S31254 undergo heat treatment processes like solution annealing at a temperature range of 1140 ºC-1200ºC. The Holding time for solution annealing at a temperature of a minimum of 30 minutes, needs to be followed by rapid cooling in air or water.
SMO 245 pipe and tubes are developed for maximum resistance to stress corrosion cracking. Chemical composition of high molybdenum and chrome, it is ideal to use in high chloride environments and again used in areas where 316 or 317l fail to corrosion.
The chemical balance allows SMO 254 pipes and tubes to present extra-ordinary resistance to carburization, oxidation, and nitriding environments. SMO 254 pipes and tubes will not embrittle even after using for long periods in the 1200°F – 1600°F range where many stainless sheets of steel become brittle.
UNS S31254 seamless pipes and tubes are most popularly used in applications where high temperature corrosive media is used. SMO 254 tubes and pipes are often used in ethylene pyrolysis, hydrocarbon cracking, furnaces for vinyl chloride and acetic acid, various valves, fittings, and many other fixtures.
Alloy 254 SMO or UNS S31254 possesses an excellent corrosion resistance in seawater and various industrial environments, various acidic mediums like hydrochloric acid, hydrofluoric acid, chloride contaminated sulphuric acid, phosphoric acid, and pickling acids based on nitric acid and hydrofluoric acid solutions.
254 SMO pipe suppliers state some of the popular applications:
- Saltwater handling
- Tall oil distillation columns
- Flue gas desulfurization scrubbers
- Components used in petroleum production
- Food processing equipment
- Process equipment in the chemical industry
- Bleaching equipment in the pulp and paper industry
- Flue-gas cleaning
- Heat exchangers.