Plate flanges

Plate flanges - what they are

Plate flanges (also called flange plates or plate blanks) are flat, usually circular discs that provide a bolted or welded connection point in a piping system. They can be supplied with a central bore to match pipe internal diameter or as a solid plate used to blank off a pipe end (often called a blind or blank flange). Plate flanges form a strong, simple joint between pipes, valves, pumps and equipment.

Materials: stainless, acid‑resistant and heat‑resistant steels

In this shop all plate flanges are made from stainless and specialty stainless steels - no aluminium or plain carbon steel is offered. Typical material families you will see are:

• Stainless steel (austenitic) - common grades include EN 1.4301 / AISI 304 (often called A2 or 304). These give good general corrosion resistance and are widely used in water, HVAC and many industrial installations.
• Acid‑resistant stainless steel - e.g. EN 1.4404 / AISI 316L (also referred to as A4 or 316L). These grades offer improved resistance to chlorides and many chemicals and are standard for food, chemical and offshore use.
• Heat‑resistant stainless steels - specialised grades are used when elevated temperatures are expected (for example certain 300‑series or specially specified heat‑resistant alloys). These are chosen where creep strength and oxidation resistance at temperature are required.

Note: European designations (EN / BS EN) and common US designations (AISI / ASTM) are often used interchangeably in specifications; if you need specific grade numbers for your project (for example 1.4301 / 304 or 1.4404 / 316L) our team can confirm suitability.

Applications and industries

Plate flanges are used across a wide range of sectors. Typical uses include:

• Blanking off pipe ends (inspection ports and maintenance isolation)
• Joining pipe sections where a simple flat connection is required
• Connecting flanged equipment such as valves, pumps and vessels
• Fabrication parts, spacers and custom flange adaptors in workshops or garages

Industries that commonly use plate flanges include oil and gas, chemical and petrochemical, marine and offshore, food and beverage, pharmaceutical, construction, automotive, HVAC and general engineering. Plate flanges are equally suitable for small garage projects and large industrial installations when the correct material and pressure rating are chosen.

Standards, pressure ratings and common designations

Plate flanges are manufactured to match common flange standards so they integrate with existing piping systems. Typical ways of specifying include:

• European / British: PN pressure ratings and EN / BS EN dimensions
• American: ANSI / ASME pressure classes (e.g. Class 150, 300)

When selecting a plate flange you will normally match the flange face, bolt hole pattern and pressure rating to the mating flange. If you need help matching PN to ASME classes or confirming bolt patterns, we can advise.

Choosing the right plate flange

To select the correct plate flange consider:

• Pipe size - internal diameter and outer diameter to match the bore and face of the mating flange.
• Pressure and temperature - choose the appropriate PN or ASME class and a material rated for expected service temperature.
• Corrosion environment - for chloride or chemical exposure select acid‑resistant grades such as 316L; for general service 304 may be sufficient.
• Joint type - whether the flange will be welded, bolted or used as a blind plate influences the flange face and finish required.
• Surface finish - pickled, polished or machined faces may be needed for sanitary or specialised applications.

Tip: Always check material certificates and flange standards for critical applications. If you are unsure, provide pipe size, operating pressure, temperature and media and we will recommend suitable plate flanges.

Installation and common uses

Plate flanges are straightforward to fit: they are aligned to the mating flange, gasket placed if required, and bolted up to the correct torque. When used as blind flanges (solid plates) they provide a reliable method to isolate piping for maintenance or pressure testing. In fabrication they are also used as flat mating faces, adapter plates and end caps.

Why choose plate flanges from stainless or specialty stainless steels

Using stainless, acid‑resistant or heat‑resistant stainless steels for plate flanges offers:

• Long service life and reduced maintenance because of corrosion resistance
• Suitability for food, pharmaceutical and chemical industries where contamination must be avoided
• Resistance to elevated temperatures where heat‑resistant grades are used

If you need assistance choosing between grades (for example 304 vs 316L or a specialised heat‑resistant alloy) contact our technical team with your application details and we will advise on the most appropriate plate flange material and specification.

Need help?

If you have specific requirements - sizes, drilling pattern, standards (PN, EN, ANSI/ASME), or a particular stainless grade - contact us with the details of your project (pipe size, pressure, temperature and media) and we will help you choose the right plate flanges.