There are many different types of steel, with the two most common in industrial applications being stainless steel and carbon steel. They often look very similar, sometimes indistinguishable from one another, yet they are vastly different in the functions they serve.
Stainless Steel versus Carbon Steel
Stainless steel has a high resistance to pitting and staining caused by corrosion, aka oxidization. However, when iron based metals like carbon steel are exposed to oxygen their chemical properties can change due to oxidation, turning a reddish-brown iron oxide which will eventually disintegrate. Though there are many applications for carbon steel in industrial products, for the purposes of this article we will focus on the advantages of stainless.
There are two primary types of stainless used in industrial fittings, 304 and 316. The difference is that 304 contains 18% chromium and 8% nickel, while 316 contains 16% chromium, 10% nickel and 2% molybdenum (also referred to as moly). The molybdenum is added to help better resist corrosion, particularly to chlorides, like sea water and de-icing salts. Plus, the chromium, unlike the iron in carbon steel, is not susceptible to oxidation.
To Summarize: Stainless Steel versus Carbon Steel
- Stainless steel has a high chromium content which provides a protective layer which serves as a corrosion and rust inhibitor.
- When carbon steel is exposed to moisture it can easily corrode and rust.
- Stainless steel is better suited in applications exposed to salt water, in food processing, pharmaceutical manufacturing and textile operations, to name a few.
- Carbon steel is usually strong enough and always less expensive than stainless for many industrial fitting applications.
Stainless steel hydraulic fittings and adapters provide significant advantages over standard steel and plastic options in many critical applications. In fact, stainless is sometimes the only practical choice.
In addition to being corrosion and rust resistant, stainless steel is a very tough metal. It is particularly resilient in very high and exceptionally low temperatures. In addition, a little known fact is the material is 100% recyclable. In fact, the composition of many stainless steel products contains recycled material, making it more environmentally friendly.
Common Applications for Stainless Steel Fittings and Adapters
Oil & Gas and Chemical Processing
Hydraulic applications in the oil & gas and chemical processing market require fittings which are designed for demanding conditions. From salt spray on offshore rigs in the north sea, to refineries, and the processing of caustic chemicals, stainless steel is the predominant choice of material in fittings and valves.
Whatever material is being transported; oil, various chemical combinations or other substances, stainless steel outperforms most other materials. The oil & gas, and chemical processing industries are naturally corrosive environments and can experience extreme temperatures and harsh conditions. That’s why stainless steel is used throughout these markets. Other exotic materials such as Monel alloys are used in oil and gas exploration where components will be exposed to “down hole” environments of elevated temperature combined with high hydrogen sulfide concentrations. Monel is used in these so called “sour wells” as the conditions prove rapidly degrading to stainless steels. However, Monel is much more expensive than stainless and used only when conditions require.
Food Processing & Brewery Equipment
The manufacturing and processing of foods and beverages, as well as alcoholic beverages, utilizes specialty manufacturing, processing, and packaging equipment that are required to withstand high temperatures and transportation of liquids through the system while staying hygienic. The equipment must also be easy to clean and disinfect during change over or before introducing a new product to the system. The cleaning process is vital to protecting against the growth of bacteria and other pathogens.
In order to withstand heat, resist pitting, cracking, potential corrosion and for ease of cleaning, stainless steel fittings, adapters and tubing are used when carrying food materials or beverages. Plus, stainless steel is achromatic to foods, so it does not affect the taste, smell or color of foods and beverages.
Equipment and components such as fittings used in the pharmaceutical industry often come into contact with high temperature, high pressure, and corrosive chemicals, and must also endure recurrent and intense cleaning treatments. According to the FDA: “Equipment shall be constructed so that surfaces that contact components, in-process materials, or drug products shall not be reactive, additive, or absorptive so as to alter the safety, identity, strength, quality, or purity of the drug product beyond the official or other established requirements.”
Because stainless steel easily withstands these conditions and requirements and is extremely hygienic it is the primary fitting and tubing material used in pharmaceutical R&D and manufacturing.
Other Industry Applications
There are many other industries that rely heavily on stainless steel fittings and components, including textiles, water treatment plants, ship building & marine equipment, mining and more. There enhanced corrosion resistance extends the service life of equipment and the temperature ratings for 304 stainless of 800°F (427°C), or 316 stainless steel of 1,000°F (538°C) along with its toughness in harsh conditions makes stainless the ideal choice in many industries and applications. Pressure ratings of industrial stainless steel fittings are often rated to 10,000 PSI, and for specialty applications can be designed for up to 20,000 PSI.