What Is a Stainless Steel Reactor and How Is It Manufactured?

Used across a wide range of industries from chemicals to pharmaceuticals and food, stainless steel reactors are core process equipment in which chemical reactions are carried out under controlled conditions. In this article we look at what a stainless steel reactor is, how it works, the stages of its manufacture and the standards used in its design.

What Is a Stainless Steel Reactor?

Stainless steel reactors are closed vessels in which chemical reactions take place under defined temperature, pressure and mixing conditions. Depending on the process, they are designed to operate at atmospheric pressure, under vacuum or under pressure. Because they are made of stainless steel they are durable, highly resistant to corrosion by many chemicals and easy to clean. Corrosion resistance does, however, depend on the product, its concentration and the temperature, so the material is assessed separately for each process.

How a Stainless Steel Reactor Works

A stainless steel reactor provides a controllable environment for the reaction. A typical reactor consists of the reaction vessel (inner shell), a heating or cooling jacket or coil, an agitator, a seal and measurement and control systems. The reaction vessel is the main section where the raw materials are mixed and the reaction takes place. The jacket is a second wall surrounding the inner shell, through which steam, hot water, thermal oil or cooling water is circulated to control the reaction temperature. Where required, the outside of the jacket is insulated to reduce heat loss.

Manufacturing Stainless Steel Reactors

Stainless steel reactor manufacturing is carried out in accordance with the applicable design codes and passes through several stages.

Design stage: Manufacturing starts with a design prepared to the client’s process requirements. The design covers the reactor’s volume and dimensions, design pressure and temperature, agitator type and speed, heat transfer area and other technical details. For pressurised reactors, wall thicknesses are calculated according to the selected design code.

Material selection: Product-contact surfaces are usually made of AISI 304/304L or AISI 316/316L stainless steel. In more aggressive media, duplex stainless steel or nickel alloys such as Hastelloy may be used. The right choice of material is decisive for corrosion resistance, mechanical strength and the service life of the reactor. Material certificates for the plates used are included in the manufacturing file.

Fabrication stage: Once the design is approved and the materials are procured, cutting, bending and rolling, welding, assembly and surface finishing are carried out. Welding is performed to approved welding procedures by certified welders, and product-contact surfaces are polished and passivated where required.

Testing and quality control: At the end of fabrication the reactor undergoes a series of tests. Hydrostatic pressure testing, leak tests, non-destructive examination of welds (dye penetrant, radiography, etc.) and dimensional checks are performed to verify that the reactor is safe and fit for purpose. Test reports and certificates are delivered together with the operating and maintenance documentation.

Stainless steel reactors play an important role in the chemical, pharmaceutical and food industries. Their durability, ease of cleaning and ability to provide a controlled reaction environment make them the preferred equipment in many applications. Careful execution of the manufacturing process produces reliable reactors and keeps industrial processes running efficiently. Since 2009, Makfen has been designing and manufacturing stainless steel reactors at its Dilovası facility.

What Standards Are Used in Reactor Manufacturing?

The standards used in reactor manufacturing are national and international regulations covering pressure equipment safety, design calculations, material properties, welding and quality control. Which codes and standards apply depends on the project, the country where the reactor will be installed and the industry.

Some of the most commonly used regulations and standards are:

1. PED 2014/68/EU (Pressure Equipment Directive): A directive, not a standard, that sets the essential safety requirements for pressure equipment placed on the EU market. Conformity is usually demonstrated through harmonised standards such as EN 13445.
2. EN 13445: The European standard for the design, manufacture and inspection of unfired pressure vessels, widely used for pressurised reactors.
3. ASME BPVC Section VIII: The pressure vessel section of the ASME Boiler and Pressure Vessel Code; it sets design, fabrication and testing requirements for reactors, particularly in the USA and on projects that specify the ASME code.
4. AD 2000-Merkblatt: A German set of rules for pressure vessels, which can also be used to demonstrate PED conformity.
5. API 650 and API 620: Standards for atmospheric and low-pressure storage tanks, not for reactors. They may apply to the raw material and product storage tanks installed alongside a reactor.
6. ANSI/ISA standards: Used for the reactor’s automation, instrumentation and control systems.
7. ISO standards: Provide the general framework, such as quality management (ISO 9001), quality requirements for welding (EN ISO 3834) and material standards.
8. AMPP (formerly NACE) standards: Referenced for corrosion and material selection, especially for reactors operating in aggressive media.

Depending on the requirements of each project, more specific standards may also apply to comply with the regulations of the relevant industry and country. It is therefore important to identify the applicable local and international regulations before starting a reactor project.