What is stainless steel?
As with all steels, stainless steel contains the same basic iron and carbon composition as other steels, but stainless steel also contains a healthy dose of chromium that gives this alloy its salt corrosion resistance fame.
The term stainless steel describes a group of materials with a slightly different alloy composition, which is responsible for the slightly different physical characteristics of each of these materials.
Chromium must be at least 10.5 percent in stainless steel. It may also contain other alloying elements that can be much higher in concentration, such as molybdenum, nickel, titanium, aluminum, copper, nitrogen, phosphorous, or selenium, depending on the grade.
Common stainless steels
Most stainless steels are made from 302 and 316 grade stainless steel. The main difference between the two grades is the addition of molybdenum, which enhances corrosion resistance very significantly in salt- and chloride-exposed environments.
302 Stainless Steel
There are many types of stainless steel, but the most common is 302 stainless steel, which is used worldwide because of its excellent corrosion resistance and low price. It contains between 16 and 24 percent chromium and up to 35 percent nickel, as well as minor amounts of carbon and manganese.
The most commonly used form of 302 stainless steel is 18-8 (18/8) stainless steel. This has an 18 percent chromium content as well as an 8 percent nickel content.
Due to its excellent corrosion resistance and value, 302 is the most common type of stainless steel used throughout the world.
It is widely used in food processing and kitchen applications, and it is also commonly found in buildings, décor, and site furnishings. 302 can withstand corrosion from most oxidizing acids, so it is easy to sanitize.
The 302 ss does have one weakness: it can be corroded by chloride solutions, or by salty environments like the seashore. The corrosion caused by chloride ions can spread beneath protective chromium barriers and compromise internal structures, resulting in pitting. The corrosive effect of sodium chloride can begin as little as 25 parts per million.
302 stainless steel is commonly used for the following applications:
- Storage tanks
- Hardware for fastening and finishing (screws, nuts, bolts, plates, handles)
- Pots and pans
- Residential sinks and sink parts
- Architectural/decorative hardware for indoors (panels, sculptures, sconces)
- Equipment tubing
- Residential appliances
316 Stainless Steel
The 316 grade is the second-most commonly used grade of stainless steel. 316 stainless steel is nearly identical to aisi 302 stainless steel in terms of physical and mechanical properties, and contains the same material composition as 302 stainless steel. A key difference is the addition of molybdenum to the 316 stainless steel, which increases corrosion resistance, particularly in the presence of chlorides.
The molybdenum in 316 stainless steel provides resistance to chlorides and other processing chemicals.
Many industrial applications that involve processing chemicals and in high-salt environments such as coastal regions and outdoor areas where deicing salts are used are commonly made of 316 stainless steel. Since 316 stainless steel is non-reactive, medical surgical instruments are also manufactured from it.
In alternative 300-series grades, molybdenum can amount to up to 7 percent. These grades provide better chloride resistance, but such heavy-duty resistance should only be needed in industrial and high concentration exposure conditions.
316 stainless steel is commonly used for the following purposes:
Industrial equipment as used in:
- Pharmaceutical manufacturing
- Chemical manufacturing
- Industrial and chemical transportation
- Pressure vessels
- Pipes and cisterns for chemical applications
- Medical equipment where non-surgical steel
- Marine equipment
- Outdoor site furnishings
- Commercial kitchens
- Producing and processing food in saline environments can be challenging
- Commercial appliances
What Is The Difference Between 302 And 316 Stainless Steel Pipe?
Grade 302 stainless steel, also known as A2, contains between 18 and 20 percent chrome and 8 to 10 percent nickel. Grade 316 stainless steel or A4 stainless steel contains 16 percent chrome, ten percent nickel, and two to three percent molybdenum. In other words, one of the biggest differences between stainless steel Aisi type 302 and 316 is the presence of molybdenum in 316. As a result of its addition, the oil is resistant to corrosion caused by chlorides, such as those found in seawater or deicing salts. The corrosion resistance of this alloy rivals that of titanium and high nickel alloys. There are also trace amounts of silicon, carbon, and manganese in grade 316 steel.
316 stainless steel is called marine grade stainless steel since it contains molybdenum. In this regard, it is the obvious choice to use it for piping on a floating oil rig and for pipelines in oil refineries. Chemical resistance is another advantage of stainless steel type 316. In addition, it is able to resist acidic substances like sulfuric acid and fatty acids at high temperatures, as well. There are temperatures up to 1600 degrees Fahrenheit that can be tolerated by stainless steel grade 316. There is a difference between grade 302 and grade 316 stainless steel in terms of strength.
Type 302 stainless steel is cheaper and easier to fabricate than grade 302 stainless steel for most other applications. For this reason, it is used in wheel covers, electrical enclosures, and general steel pipes. As a matter of fact, 302 stainless steel is the most widely used austenitic stainless steel in the world. This steel is stronger than steel that is described as “mild”. In addition to that, it is less heat sensitive than even grade 302 steel. The material has the ability to withstand corrosion from most oxidizing acids, making it an easy material for sanitization. As a result, 302 stainless steel is considered to be one of the best materials for applications including food processing equipment and hot water systems.
It is impossible to tell the difference between the two grades of stainless steel. It is necessary to have a material test report to distinguish between them if they are not specially marked. A 6 inside a circle may be stamped on items made of stainless steel 316. This type of marking is rarely found on grade 302 stainless steel.
A typical application for stainless steel 302 pipe would be in heat exchangers. Heat exchangers transfer heat between two or more fluids. Because SS 302 welded pipes are more cost-effective than other options, they are more commonly used in heat exchangers. Heat exchangers need moderate corrosion resistance and good tensile strength, but SS 302 pipe can cater to their needs without causing a dent in the buyer’s wallet. Aside from that, stainless steel 302 erw pipe performs its functions rather efficiently.
As Thus, ASTM A312 tp 302 seamless pipes are widely used across many industries, including power plants, chemical plants, and oil refineries.refrigeration, air conditioning, petrochemical plants, and petroleum refineries. ASTM A312 specified AISI 302 pipe is designed for applications involving both high-temperature conditions and general corrosive conditions. Suppliers of the highest quality stainless steel 302 pipe.
The ASME SA312 grade 302 pipe is usually cold-worked in order to permanently alter the crystal structure of the alloy through the application of mechanical force in order to permanently alter the structure of the alloy. Hence, this leads to an increase in the tensile strength properties of the seamless SS 302 pipe, which can be attributed to the use of heat, without the use of any chemicals in the process.
In the world of materials, stainless steel refers to a group of materials that have a slightly different alloy composition, which is responsible for the slightly different physical characteristics of each of these materials.
The corrosion caused by chloride ions can spread beneath protective chromium barriers and compromise internal structures, resulting in pitting.
The main difference between the two grades is the addition of molybdenum, which enhances corrosion resistance very significantly in salt- and chloride-exposed environments.