A high-end stainless-steel alloy mainly designed to provide resistance against saltwater is the 250 SMO fasteners. It comprises 6% Molybdenum, which provides good corrosion resistance and gives much higher strength than other stainless steels. It is an ideal solution to environments with high chlorides. It demands heavy usage of chlorine or chloride.
In chloride containing environments, SMO 254 fasteners offers good corrosion resistance. It has higher contents of molybdenum, chlorium and nitrogen. It is different than other types of stainless steels due to higher ductility and higher strength. Mostly used in marines, petrochemicals and chemical industries.
SS 316 is on the other hand, known for high-temperature tolerance and good corrosion resistance. This nature is due to combination of metals only, which include, molybdenum, nickel and chlorium. SS 316 is used in food and processing industries, pharmaceuticals and medical devices.
254 SMO Bolts
UNS S31254 hex bolts
DIN 1.4547 stud bolts
To install a 254 SMO Fasteners, we have to first have 254 SMO bolts, screws and nuts. Below are some of the steps that ensure safe and convenient ways of installing a fastener.
|Metric Size||Imperial Size||Length|
|M1.2 to M48||Stanadard #00 to 4"||upto 1500 mm|
|ASTM A193| ASME SA193||BSW, METRIC, UNF, UNC, BSF, Custom|| |
254 SMO stainless steel nuts
Alloy 254 screws
6 Moly threaded rod
|254 SMO|| S |
| Cu |
| C |
| Mn |
| P |
| Si |
|Cr Chromium||Ni Nickel|| Mo |
| N |
|0.015 max||0.50–1.00||0.020 max||1.00 max||0.030 max||0.80 max||19.5–20.5||17.5–18.5||6.0–6.5||0.18–0.22|
|Elongation (min 2"):||35%|
|Tensile Strength:||98 ksi min|
|Hardness (Rockwell B Scale):||96 HRB max|
|Yield Strength:||45 ksi min|
|SMO 254||2378||S31254||1.4547||–||–||Z1 CNDU 20.18.06Az||X1CrNiMoCuN20-18-7|
When it comes to 254 SMO and a super duplex, it has a lot of difference. A 254 SMO is non-magnetic, easier and more convenient to weld and has wide temperature tolerance range.
A SMO 254 is more convenient than a super duplex because it has more nickel and molybdenum content, making it more expensive and has significantly lower strength. Therefore, it is widely used in mode of applications where usage of super duplex is limited.
On the other hand, flue gas desulphurisation systems in power stations make use of super duplex stainless steel, which result in lower temperatures due to its continuous operations.
UNS S31254 hex bolts are used in atmospheres of high chlorine such as blackwater or seawater. It ensures superior toughness and high strength at cryogenic temperatures. It also exhibits good mechanical properties at both moderate and high-temperature.
They are forged to 982 – 1149 degrees. Post process annealing is done to attain maximum corrosion resistance. They are also resistant to uniform corrosion. The grade of fasteners is significantly stronger than other steel alloys.
This fastener comprises of various components. Different categories of nuts are available, but 254 SMO stainless steel nuts come with high-level contents of Molybdenum. It is ideal for high temperatures and evenly distributing load. It should be only used when the temperature is below 350-degree Fahrenheit.
A thin plate with a hole at the centre which distributes the load of a threaded fastener is the WNR 1.4547 washers. There are several other types of fasteners which are available such as Bolts, screws, studs, threaded rods and many more.
|254 SMO Nut Size |
|Jam Nut||Hex Nut||Nylock Nut|
|Weight (lbs.) Per 100 Pieces||Sizes||B||A||C|
|Inside Diameter||Thickness||Outside Diameter|