Stainless steel plate flanges 1.4307/304L — Overview

Stainless steel plate flanges 1.4307/304L are flange components manufactured from the low‑carbon variant of the common 304 stainless steel. They are cut or machined from flat stainless plate to form a flange body used to join pipework, equipment covers, tanks and structural assemblies. In everyday language you may see this material described as stainless steel 304L (AISI/ASTM), while in European practice it appears as EN 1.4307 (UNS S30403 in US notation). These plate flanges combine the corrosion resistance and formability of austenitic stainless steel with improved weldability due to the reduced carbon content.

What is a plate flange and how is it used?

A plate flange is a flange made from flat plate rather than cast or forged material. Typical uses include:

• creating a bolted connection point on flat surfaces or tank walls
• fabricating blind flanges (to close pipe ends) or loose lap‑type flanges
• producing custom flange spools where standard pipe flanges are not suitable
• machined or drilled flanges for bolting to existing pipework or equipment

Plate flanges are chosen when you need a robust, flat connection built from plate stock — for example to match a custom hole pattern or to integrate with previously fabricated assemblies.

Material details — 1.4307 / 304L

The designation 1.4307 corresponds to the low‑carbon version of 304 stainless steel, commonly referred to as 304L (AISI 304L, UNS S30403). Key practical characteristics include:

• good general corrosion resistance in air, potable water and many chemical environments
• improved resistance to intergranular corrosion after welding due to lower carbon content
• excellent formability and cold workability for cutting, drilling and machining
• generally non‑magnetic in the annealed condition (may become slightly magnetic if cold worked)

For reference to standards, 304L is commonly listed in BS EN standards for stainless steels (for example BS EN 10088), and is widely used across Europe and the UK as well as the US.

Typical industries and applications

Stainless steel plate flanges 1.4307/304L are suitable across a wide range of sectors:

• food and beverage processing — hygienic connections and covers
• pharmaceutical and healthcare equipment — where cleanable stainless surfaces are required
• chemical and petrochemical plants — piping and vessel interfaces where corrosion resistance is needed
• marine and offshore — internal fittings, deck equipment and non‑critical seawater applications
• construction and architectural projects — decorative and structural connections
• automotive, HVAC and mechanical workshops — bespoke repairs and fabrications
• hobbyists and small garage projects — corrosion‑resistant components for custom builds

Advantages of choosing 1.4307/304L plate flanges

• Better weldability: the lower carbon content of 304L reduces the risk of sensitisation during welding, making it a preferred choice for welded flange joints.
• Corrosion resistance: suitable for many general‑purpose environments where stainless performance is required.
• Versatility: easy to machine, drill and form to custom sizes or hole patterns from plate stock.
• Availability: 304L (1.4307) is widely available and well understood by engineers and fabricators.

Standards, compatibility and practical notes

When specifying plate flanges, check compatibility with the flange standards and bolt patterns you need — common systems include EN/PN (European), BS and ANSI/ASME (US) flange dimensions. The material marking EN 1.4307 (304L / UNS S30403) should be used to ensure you get the low‑carbon grade appropriate for welded assemblies.

Remember that stainless grades suitable for aggressive chloride‑rich environments (e.g. offshore splash zones or concentrated brines) may require higher alloyed grades such as 316/1.4404; 304L is excellent for general applications but has limits in very corrosive conditions.

Who should buy stainless steel plate flanges 1.4307/304L?

These plate flanges are aimed at engineers, fabricators, plumbers, installers, maintenance teams and DIY enthusiasts who need a corrosion‑resistant flange solution that is easy to weld and machine. If you require a flange for hygienic processing, general industrial piping, tank connections or custom fabrications, 1.4307/304L is a practical and economical choice.

Ordering tips

• Check product listings for available diameters, thicknesses and drilled patterns.
• If you have a specific bolt pattern or drawing, confirm whether the flange can be supplied drilled or machined to that specification.
• Specify the material designation (EN 1.4307 / 304L / UNS S30403) to ensure the low‑carbon variant is provided for improved weldability.

For more information on sizes, drilling patterns and delivery options, please consult the product pages or contact our team — we specialise exclusively in stainless, acid‑resistant and heat‑resistant steels and can advise on the right grade and flange configuration for your project.