The two most common stainless steel grades are 304 and 316. The main difference is the addition of molybdenum, an alloy that significantly improves corrosion resistance, especially in environments with more salt or chloride exposure.
304 stainless steel is the most common form of stainless steel in the world due to its excellent corrosion resistance and value. It contains 16% to 24% chromium and up to 35% nickel, as well as small amounts of carbon and manganese.
304 stainless steel does have one weakness: it is susceptible to corrosion from chloride solutions or saline environments such as the coast.
316 stainless steel has more carbon in it than 316L. This is easy to remember, as the L stands for “low.”
316L is very similar to 316 in almost every way.?
316L, however, is a better choice for a project that requires a lot of welding because 316 is more susceptible to weld decay than 316L (corrosion within the weld).
316 can be annealed to resist weld decay.
316L also is a great stainless steel for high-temperature, high-corrosion uses, which is why it’s so popular for use in construction and marine projects.
904L grade stainless steel is unlike any other steel. Due to its extra amounts of chromium, molybdenum, nickel and copper, 904L steel features superior resistance to corrosion, rust and acids.
Alloy 347 (UNS S34700) is columbium stabilized austenitic stainless steel plate with good general corrosion resistance and somewhat better resistance in strong oxidizing conditions than 321 (UNS S32100).
The addition of copper to this grade gives it better corrosion resistance than conventional chromium-nickel stainless steels, especially against sulfuric, phosphoric and acetic acids. However, the use of hydrochloric acid is limited.
It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800 ¨C 1500¡ãF (427 ¨C 816¡ãC).?
Stainless steel 904L / 1.4539 material can be used to make hot and cold rolled sheet and strip, semi-finished products, bars, rolled wire and profiles, as well as seamless and welded pipes for pressure applications.
The alloy has good oxidation resistance and creep strength to 1500¡ãF (816¡ãC). It also possesses good low temperature toughness.
Alloy 904L outperforms other austenitic stainless steels due to the higher degree of alloying of nickel and molybdenum.
Alloy 347H (UNS S3409) stainless steel plate is the higher carbon (0.04 ¨C 0.10) version of the alloy.
The high chromium content promotes and maintains a passive film that protects the material in many corrosive environments.
When selecting stainless steels that must withstand corrosive environments, austenitic stainless steels are often used.
These connections are embedded inside concrete walls before the pouring of concrete. This system must be aligned properly before concrete pouring because it needs to withstand the weight and force of the structure.
They generally easily corrode because of the elements they exposure; water and natural electrolytes. Acceptable protective monitoring must be done when applying pipe spool systems.
Pipe spool fabrication is very important because the construction of the ship and other marine industries require intensive piping. Pipe spools create great advantages because they reduce the limitations of space on site.
With this advantage, all of the pipeline using industries has a great opportunity to increase their pipeline system efficiency and decrease their need for workforce and time.
Pipe spool systems are mostly used in power plants and petroleum refineries which requiring intensive piping. These systems include carriage and transport of fluid and gas and these transportation systems need lots of connection parts. In these systems, there is no place for mistakes.
Pipe spools are produced by the usage of raw pipes and pipe fittings. The cutting process of the raw pipes is done with prespecified sizes that are suitable for the pipe fittings and other components.
The following procedure after the marking is the cutting step. The way of cutting differs for various materials. Thus, for carbon steels, the flame cutting method is utilized. Moreover, stainless steel components can be cut using a plasma arc cutting machine. If the plasma arc cutter is used some certain conditions must be maintained.
Pipe spools are pre-fabricated to reduce field installation costs and provide higher quality in the products. They are generally flanged to obtain the connection to other spools. The spool fabrication is normally performed by special companies having the required infrastructure.
The plasma arc cutter is utilized for large pipes (above 28 inches of nominal pipe size) and its use is also beneficial for cutting off branches. If possible, an internal case must be located into pipes or fittings, in order to protect them from the spatters which are created by the plasma arc cutter. After the cutting, and edge preparation must be maintained.
These specialist fabricators produce the system under the specified set of quality and accuracy to obtain proper fit at the site and to maintain the necessary technical properties defined by the client.
The surface edges of the components must be even and the surface impurities must be removed. A beveling process is implemented for the edges of the parts. A grinding machine is employed for the beveling process. The type of grinding machines for beveling differs for stainless steel components and carbon steel components.
For the supply of water and flammable gases, steel pipes are the most useful pipes. They are used in many homes and businesses to transfer natural gas or propane fuel. They also used for fire sprinkler systems due to their high heat resistance.
