Stainless steel blind flanges 1.4541 / 321

What is a stainless steel blind flange 1.4541 / 321?

Blind flanges (also called blank flanges) are solid discs used to close the end of a pipe, valve or pressure vessel opening. They allow safe sealing of a system for commissioning, testing, maintenance or permanent termination. In this category the flanges are made from stainless steel grade 1.4541, commonly known as AISI 321 (also referenced as UNS S32100 or DIN X6CrNiTi18-10). This is a titanium‑stabilised austenitic, acid‑resistant stainless steel that combines good corrosion resistance with excellent weldability.

Material and technical notes

1.4541 / 321 is an austenitic stainless steel grade designed to resist intergranular corrosion after exposure to elevated temperatures. The titanium stabilisation (the “Ti” in the designation) helps prevent sensitisation during welding and heat treatment. In practical terms, this makes 321 a preferred choice where welded assemblies are subject to heat or cyclic elevated temperatures and where resistance to many aggressive agents (including some acids, sea water and hot petroleum products) is required.

Common equivalents and notations you may see:

• European / EN / DIN: 1.4541, X6CrNiTi18-10
• American / AISI / UNS: AISI 321, UNS S32100
• Common names: stainless steel 321, acid‑resistant stainless steel

Where and how blind flanges are used

Blind flanges 1.4541 / 321 are widely used to cap pipe ends or access ports and to allow pressure testing, cleaning and future modifications. Typical uses include:

• Sealing pipe ends and outlets during commissioning and pressure testing
• Permanent end caps where disassembly is not required
• Temporary blanking for maintenance and system isolation
• Closure of tanks, vessels and heat exchanger nozzles

Industries and customers

These blind flanges are suitable for a broad range of sectors, from small workshop or garage projects to heavy industrial applications. Typical industries and users include:

• Chemical and petrochemical plants
• Food and beverage processing (breweries, dairies, canning)
• Pharmaceutical and biotech equipment
• Oil & gas and offshore installations
• Shipbuilding and marine systems
• Power generation and heat exchangers
• Water treatment and desalination
• Construction, HVAC and general fabrication shops

Key benefits of 1.4541 / 321 blind flanges

• Corrosion resistance: Good resistance to many corrosive media and to intergranular corrosion after welding thanks to titanium stabilisation.
• Weldability: Well suited to all standard welding methods, making it easy to fit into welded systems.
• Temperature performance: Suitable for applications at elevated temperatures where stabilised austenitic steel is required.
• Durability: Long service life in demanding environments such as chemical plants, food processing and offshore.

Standards, dimensions and finishes

Blind flanges in this category are offered to common flange standards and pressure ratings used in the UK and internationally, including EN/PN (European) and ASME (American) specifications. They are available in a range of diameters and face types (for example raised face or flat face) and with standard bolt hole patterns to match mating flanges. Surface finishes range from machined to polished, depending on application (e.g. hygienic finishes for food/pharma).

How to choose the right blind flange

When selecting a blind flange 1.4541 / 321, consider:

• Correct flange standard and bolt pattern (EN/PN vs ASME)
• Pipe size and pressure rating required for your system
• Face finish (machined, raised face or flat face) and gasket compatibility
• Environmental factors (chemical exposure, temperature, marine conditions)
• Weldability or bolt‑on installation preference

If you are unsure which variant you need, contact our technical team with the operating conditions (media, temperature, pressure and mating flange standard) and we will advise the best option.

Who should buy these products

Engineers, procurement officers, maintenance teams, fabricators, shipyards and contractors who require reliable, acid‑resistant blind flanges for welding or bolted connections will find 1.4541 / 321 a practical choice. We also serve small workshops and DIY professionals who need durable stainless steel solutions for corrosive or high‑temperature environments.

Note: Our shop specialises exclusively in stainless, acid‑resistant and heat‑resistant steel products—no aluminium or plain carbon steel is offered. For help specifying sizes, standards or finishes for stainless steel blind flanges 1.4541 / 321, please get in touch.