Plate Flanges

Flat flanges (also known as plate flanges) are a type of flange used to connect pipes, valves, and equipment in piping systems. They feature a flat mating surface where a gasket is placed; once the bolts are tightened, the assembly creates a leak-proof connection. In colloquial language, they may also be referred to as slip-on plate flanges or simply flanges.

Where are flat flanges used?

Flat flanges are used virtually everywhere a detachable, leak-proof connection between installation components is required. Typical applications include:

• water and heating installations
• food and pharmaceutical industry (due to hygiene requirements)
• chemical and petrochemical industry
• shipbuilding and offshore industry
• automotive and machinery industry
• construction and sanitary installations
• small workshops and garage solutions

In our store, we offer exclusively flanges made of stainless steel, acid-resistant steel, and heat-resistant steel. Below is a brief overview of steel types using both colloquial and technical designations (EU / AISI):

• Austenitic stainless steel (e.g., 304)– designations: EN 1.4301 / AISI 304 (colloquially A2). A universal steel resistant to corrosion in most conditions, commonly used in sanitary and food installations.
• Acid-resistant steel (e.g., 316 / 316L)– designations: EN 1.4401 / 1.4404 (AISI 316 / 316L, colloquially A4). More resistant to corrosion in environments containing chlorides and acids; recommended for chemical, offshore, and marine installations.
• Ferritic steel (e.g., 430)– designations: EN 1.4016 / AISI 430. Steel resistant to oxidation in moderate conditions, used where the highest corrosion properties are not required.
• Heat-resistant steels (e.g., AISI 310)– used when connections are exposed to high temperatures. (Designations may vary depending on the grade; when selecting material for high-temperature operation, it is advisable to consult a technical advisor.)

How to choose the material

The choice of steel depends on: the medium (water, vapors, acids), operating temperature, corrosion and mechanical resistance requirements, and the environment (e.g., proximity to the sea). For chemically aggressive media, 316/316L is usually chosen; for general applications, 304; for high-temperature work – heat-resistant steels.

Flat flanges are manufactured in accordance with industrial standards, which facilitates their selection and assembly with components available on the market. The most common standards are European (e.g., EN / PN) and American (ASME / ANSI) standards. In practice, this ensures compatibility of bolt holes, internal diameters, and pressure classes, which is crucial when matching pipes and valves.

When installing flat flanges, the following are important:

• selection of the appropriate gasket (material and type) – the gasket must be compatible with the medium and temperature,
• appropriate bolts and nuts and their tightening torque – this guarantees the tightness and durability of the connection,
• cleanliness of the mating surfaces and correct compression,
• matching the flange material to the pipe material and operating conditions (minimizing stress corrosion, potential differences, etc.).

Our offer is addressed to a wide range of recipients: installers, construction companies, industrial plants, machinery services, shipyards, the food and pharmaceutical industries, as well as hobbyists and small workshops. Flat flanges are components of both large industrial installations and simple garage solutions – wherever solid mounting and the possibility of disassembly are required.

Industries where flat flanges are most commonly used

• chemistry and petrochemistry
• food and pharmaceutical industry
• shipbuilding and offshore industry
• HVAC and heating installations
• automotive and machinery industry
• construction and sanitary installations

When choosing flat flanges, pay attention to the material, standard (EN/ASME), internal diameter matched to the pipe, bolt hole pattern, and type of seal. If you are not sure which steel will be best for your application – contact our technical advisor. We will help you choose the right flange for your installation and operating conditions.

Flat flanges are a fundamental mounting element in piping installations – by choosing stainless, acid-resistant, or heat-resistant steel, you ensure durability and resistance even in demanding conditions.