Category Archive: Stainless Steel

Differentiating 303, 304, & 316 Stainless Steel

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Class 300 stainless steels are austenitic chromium-nickel alloys that are highly corrosion resistant and non-magnetic, displaying excellent formability and temperature resistance. Three of the most common austenitic stainless steels are types 303, 304, and 316. Although related, these alloys differ in areas like chemical composition, material capabilities, and cost.

Type 303

The base composition of type 303 stainless steel is approximately 18% chromium and 8% nickel. The additions of 0.15% sulfur or selenium and phosphorus make type 303 the most machinable alloy of the class but slightly reduce its corrosion resistance. Despite this, it is still an optimal material for components that require significant machining or tight tolerances, such as nuts and bolts, screws, bushings, fasteners, bearings, and more. Type 303 is regarded as a cheaper, more machinable alternative to similarly composed 304 stainless steel.

Type 304

The most commonly used austenitic stainless steel, type 304, is composed of 18% chromium and 8% nickel with low levels of carbon. This alloy is highly resistant to oxidation and corrosion, durable, and easy to fabricate. Considered the most versatile stainless steel of the class, type 304 has uses in a range of applications across diverse industries—from architectural details to kitchen appliances to automobile parts. Type 304 is easily accessible and less expensive than 316 stainless steel.

Type 316

Composed of slightly higher levels of chromium (16-18%) and nickel (10-14%) than types 303 and 304, the most distinguishable properties of 316 stainless steel come from the addition of 2-3% molybdenum, an element which significantly improves the alloy’s corrosion resistance. Type 316 also exhibits improved heat tolerance, resistance to creep and pitting, and excellent tensile strength. Known for its ability to withstand the effects of exposure to chlorides, the alloy is used extensively in chemical and marine applications, as well as a number of other industries. Type 316 has lower formability than 303 or 304 stainless steels, but its higher resistances make it more expensive to source.
The characteristics responsible for differentiating these common class 300 stainless steels also uniquely position each alloy to perform for specific applications.

Applications of 303 Stainless Steel

The highly machinable, non-magnetic, and non-hardening type 303 stainless steel is well-suited to applications requiring tight tolerances and heavy machining, like in the manufacturing of small parts. Typical uses of this alloy include things like:

Applications of 304 Stainless Steel

The extreme versatility of type 304 makes it the most widely used stainless steel on the market. Offering exceptional corrosion resistance and durability, this alloy is suitable for a spectrum of uses across nearly every industry. Some of the most common applications are:

Applications of 316 Stainless Steel

Offering the greatest resistance to a variety of corrosive elements, type 316 stainless steel is the most appropriate alloy for applications with continuous exposure to harsh environments or where strength and hardness are a critical factor. This includes uses such as:

  • Stainless steel floats
  • Marine parts
  • Outdoor electrical enclosures
  • Chemical and pharmaceutical equipment
  • Medical devices and equipment

Stainless Steel Components by Stafford Manufacturing Corp.

Stafford Manufacturing Corp. is a global manufacturer and distributor of shaft collars, rigid shaft couplings, and specialty mechanical components used in OEM and MRO applications for industrial and consumer products. The inclusion of types 303, 304, and 316 stainless steels in our standard and custom components plays a pivotal role in enhancing their quality and durability. Our selection of stainless steel products includes:

  • Threaded bore shaft collars
  • Two-Piece Split Clamp Collars
  • Set Collars
  • Hinge Collars
  • Square and hexagonal bore shaft collars
  • Rigid shaft couplings and shaft adapters
  • Metric shaft collars, rigid shaft couplings, and components

For additional information on stainless steel material considerations for your next application, or to learn more about the Stafford advantage, contact us today.

316 Stainless Steel for Wastewater | Stafford Mfg.

Posted by Stafford Manufacturing Corp. on

Wastewater treatment is essential for a healthy environment. Wastewater is used water from homes, businesses, and industries and can come from appliances and fixtures such as bathtubs, sinks, toilets, and washing machines. It also includes storm run-off from parking lots, roads, and roofs. Wastewater treatment reduces pollutants to a level that does not overwhelm nature when it is released back into the environment. 

There are two main stages of wastewater treatment: primary and secondary. The primary wastewater treatment removes any solids that float or settle to the bottom while the secondary further cleans the wastewater using biological processes. In potable water treatment plants, the materials used for the aeration pipes, valves, tanks, and transfer pipes can affect the quality of the purification process. The most common option for wastewater applications is stainless steel. 

Why Stainless Steel Is Used in Wastewater Treatment Plants

Stainless steel is corrosive-resistant and adds no toxic chemicals to the water. Corrosion usually occurs in pipe crevices when there is a bend or join in panels. With stainless steel, crevice corrosion is rare. 316 Stainless steel contains 2% molybdenum, which helps resist corrosion from chlorides, making it popular for potable water treatment plants where certain chemical content could increase corrosion. Carbon steel has a much lower resistance to corrosion and is therefore not the best choice for wastewater treatment. Though stainless steel is more expensive than steel, it results in far lower maintenance and replacement costs. 

Advantages of Stainless Steel

Stainless steel is available in many grades, which depends upon varying levels of carbon in the steel. The two most common types used in wastewater treatment processes are duplex grade and austenitic grade. These have the highest corrosion resistance compared to the other types. Besides stainless steel’s low corrosive properties, there are many other advantages, including: 

  • Minimal loss of metal degradation
  • High strength
  • Ductility
  • No UV light degradation

Limitations of Stainless Steel

While choosing the right grade of stainless steel is important, there may be some limitations. In environments where there are changing pressures, stainless steel can risk fatigue over time. Several grades of stainless steel  (such as 303 and 304) are susceptible to certain types of corrosion, including crevice corrosion, chloride pitting, pinhole leaks, and external corrosion. Some ways to ensure the longest life of stainless steel used for wastewater applications include: 

  • Drain pipelines during periods of non-use to prevent stagnant water, which encourages microbial activity that causes corrosion to occur. 
  • Mill pickling stainless steel pipes to help control surface corrosion. Heat tints near welded areas can make them susceptible to biocorrosion and the pickling process helps provide a corrosion-resistant surface. 
  • Follow proper operation guidelines to prevent the beginning of corrosion caused by scaling, over chlorination, poor fabrication, or MIC. 

Stainless Steel Products Suited for Harsh Environments From Stafford Manufacturing

Stainless steel can be an effective material for use in harsh environments, such as wastewater treatment facilities. Stafford Manufacturing offers both standard and custom machined parts made from corrosion-resistant stainless steel in a variety of grades to best suit your application. Contact our team to learn more about our product selection for your water treatment needs.