Petroleum refineries are not like conventional factories. They are large-scale industrial complexes that span a range of diverse yet interlined chemical processes. These include but are by no means limited to fractional distillation, naphtha hydrotreatment, catalytic reformation, steam reformation, and so on. The commonality between these challenging activities is that raw materials are all derived from crude oils; naturally occurring petroleum extracted from deposits in the earth’s crust.

Challenges in Refining & How 304h Stainless Steel Can Help

Modern refining of oil and gas has evolved around the need to reach optimal efficiencies and to utilise as many of the chemicals involved as possible. This is achieved through cyclical and tandem processing of compounds in various states. For example: fractioning columns separate crudes into different liquid state constituents based on their molecular weights, while steam reforming converts natural gas into hydrogen.

Another commonality between these varied processes is the routine presence of highly corrosive compounds. Even chemicals that are not directly corrosive (i.e. hydrogen gas) can contribute to complex structural failure mechanisms, such as hydrogen embrittlement of steel.

Key Properties of 304h Stainless Steel

304h is a high carbon stainless steel that is commonly used to engineer pressure vessels and high-temperature processing equipment. As an austenitic grade, 304h stainless steel already benefits from elevated thermodynamic stability but the increased carbon content in what is primarily a chromium-nickel alloy enables 304h stainless to withstand the extremes of processing temperatures. Additionally, it boasts excellent creep strength in both the short and long-term, making it an economically viable solution for extended performance with minimal maintenance requirements. But why does all this matter in the context of petroleum refineries?

Petrochemical Use Cases of 304h Stainless Steel

Firstly, the outstanding thermodynamic stability and high-temperature performance of 304h stainless steel makes it the ideal candidate material for large-scale heat exchangers.

Typically formatted as a bundle of steel tubes enclosed within a pressurized shell, 304h heat exchangers operate by channelling fluid from a hot process through the inner tubes and cooler fluids through the outer shell. Heat transfer through the steel results in liquid-to-liquid heat exchange via the interface of 304h stainless steel. Naturally, this requires outstanding formability and resistance to aggravation by harsh chemicals alongside the necessary thermal performance.

Secondly, 304h stainless steel displays admirable corrosion resistance across the full spectrum of petroleum processes. It exhibits limited hot corrosion sulphidation in distilleries and resists attack by naphthenic acid. Additionally, it is extremely resilient in hydrogen-rich environments that may contribute to HIC and stress-corrosion cracking (SCC).

304h stainless steel is subsequently used in a wide range of petrochemical applications, from fractionators to overhead condensers.

Looking for 304h Stainless Steel?

Masteel is one of the UK’s leading suppliers of pressure-vessel grade alloys, including high carbon 304h stainless steel. If you need a high-temperature solution for a demanding process, why not contact a member of the team today for full specifications?