Blind Flanges

A blind flange is a component without a flow opening – it is mounted between a pipe flange and secured with bolts. Its task is to cut off the flow of media (liquids, gases) and maintain tightness and strength parameters in accordance with the designed pressure class. In practice, there are various types of mating surfaces (e.g., raised face – RF, flat face – FF), and the choice depends on the type of seal and installation requirements.

• Testing and maintenance: closing a section of the pipeline during pressure tests or repairs.
• Chemical and petrochemical industry: leak-proof shut-off of pipes transporting aggressive media.
• Food and pharmaceutical industry: hygienic closure of process installations (with appropriately selected steel grade and surface finish).
• Shipyards and offshore: sealing pipe ends and equipment exposed to marine corrosion.
• Construction, HVAC, automotive, workshops: from simple garage applications to heating and cooling installations.

In our offer, all blind flanges are made exclusively of stainless steel, acid-resistant steel, or heat-resistant steel. Below is a brief explanation of the terms used and popular grades:

• Stainless steel (stainless steel, inox) – the most commonly used grades are AISI 304 (European des. 1.4301, X5CrNi18-10) – good corrosion resistance under standard conditions.
• Acid-resistant steel (acid-resistant steel) – popular grades are AISI 316 / 316L (1.4401 / 1.4404). They contain an additional molybdenum alloy, which improves resistance to chemically aggressive environments, hence they are common in the chemical, food, and marine industries.
• Heat-resistant steel (heat-resistant steel) – special steel grades designed for operation at elevated temperatures; used where oxidation resistance and maintaining mechanical properties at high temperatures are essential.
• Other functional terms: in colloquial language, you may encounter terms such as ferritic steel or austenitic steel – these refer to the microstructure of the alloy and affect mechanical properties as well as corrosion resistance.

Blind flanges are manufactured to fit standard piping systems. When choosing, pay attention to:

• nominal diameter (DN) and pressure class (PN) in the European/EN system, or ANSI/ASME class (e.g., class 150, 300) for installations according to American standards;
• bolt hole pattern and spacing– must match the mating flange;
• mating surface type (RF – raised face, FF – flat face, or possibly RTJ) adapted to the gasket;
• material and steel grade– selected based on the medium (corrosiveness, temperature) and sanitary-hygienic requirements;
• thickness and construction– affecting strength at a given operating pressure.

• Before installation, check the compatibility of the hole spacing and pressure class.
• Select the appropriate gasket (material and shape) for the flange type and medium.
• Use the correct bolt tightening torque to ensure a uniform seal and avoid deformation.
• In chemically aggressive environments, choose acid-resistant grades (e.g., 316/316L) – this will reduce the risk of corrosion.

Blind flanges are used by:

• installation and service companies,
• industrial plants (chemical, petrochemical, food),
• shipyards and the offshore industry,
• HVAC companies and the construction sector,
• workshops, small manufacturing enterprises, and DIY customers looking for durable installation solutions.

In our shop, you will find blind flanges made of stainless, acid-resistant, and heat-resistant steel, available in various diameters, pressure classes, and surface finishes. We are here to help with your selection – if you need to match a flange to a specific DN/PN or ANSI/ASME standard, provide your installation parameters, and we will advise the appropriate solution.

Summary: Blind flanges are essential components for sealing pipeline sections and equipment. Choosing the right material (stainless steel, acid-resistant steel, heat-resistant steel), pressure class, and mating surface type ensures the safety and durability of installations in various industries – from garage setups to offshore applications.