What are reduced thickness flanges?

These flanges keep the bolt pattern of a standard flange but have a flat face and a reduced thickness. Because the drilling matches EN1092-1 PN16 and ANSI B16.5 150LB flanges, they bolt up to the standard pattern.

They aren’t a like-for-like replacement for a full specification flange, and that’s where the cost saving comes from. In our listings they appear as flat face slip-on bored O/D flanges (FFSO) and flat face blind flanges (FFBL), with the thickness shown in the product name, and you can filter the range by rating to see PN16 or 150LB flanges.

Why were reduced thickness flanges developed?

A full specification flange is made thick enough to meet the standard’s pressure and temperature ratings. On hygienic and metric pipework, that thickness isn’t always needed, so you can end up paying for strength the duty doesn’t call for.

Reduced-thickness flanges were developed to give a more cost-effective solution in those cases as they use less material.

When are reduced thickness flanges a good fit?

They suit hygienic and metric pipe and fittings where the duty doesn’t call for a full thickness flange. In those cases you get a flange that bolts up as normal at a lower cost. Good fits include:

• Hygienic pipework lines, where the flange sits alongside our hygienic fittings.

• Metric tube systems, where the tube is sized by outside diameter and you want a flange drilled to a standard pattern.

• Joints with a flat faced flange, because reduced thickness flanges are flat faced too.

• Jobs where a full specification flange would cost more than the pressure and temperature call for.

Because they’re thinner than a standard flange, they’re not designed for every application. If the line runs at higher pressures or temperatures, or you need a raised face, a full specification flange is the safer choice.

What is the difference between a reduced thickness flange and a full specification one?

The main differences are the face and the thickness. A reduced thickness flange has a flat face and is thinner, while a full specification flange follows the standard’s thickness and, in many types, has a raised face.

The drilling is the same, so the choice comes down to the duty. If you need the full rating or a raised face, choose a standard flange from our EN1092-1 flanges or ANSI B16.5 flanges ranges.

What should you check before ordering?

Check the face of the flange it will join, as these are flat-faced. Then check the drilling, which will be either the EN1092-1 PN16 pattern or the ANSI B16.5 150LB pattern.

If your tube is sized by outside diameter, our RFSO bored O/D flanges are a full specification alternative bored to suit it. They’re available in 304 and 316, and they work alongside our hygienic fittings.

What should you tell us when you enquire?

Reduced thickness flanges aren’t designed for every duty, so please tell us:

1. The size and the drilling you need, either the EN1092-1 PN16 pattern or the ANSI B16.5 150LB pattern, because that decides what the flange will bolt up to.

2. The grade, either 304 or 316.

3. How many you need.

4. The pressure, temperature and media involved.

That lets us confirm whether a reduced thickness flange suits your system, or whether a full specification flange would be the safer choice.

Frequently asked questions

What are reduced thickness flanges?

Reduced thickness flanges are flat-faced stainless steel flanges that are thinner than a full specification flange. We developed them for hygienic and metric pipe and fittings, as a more cost-effective option when a full specification flange isn’t required.

Do reduced thickness flanges match standard flange drilling?

Yes. They’re drilled to match EN1092-1 PN16 and ANSI B16.5 150LB, so they bolt up to the standard pattern.

Are reduced thickness flanges suitable for every application?

No. Because they’re thinner than a standard flange, they’re not designed for every duty. Tell us the pressure, temperature and media, and we’ll say whether a reduced thickness flange suits.

Are reduced thickness flanges flat face or raised face?

They’re flat faced. Our listings include flat face slip-on bored O/D flanges and flat face blind flanges, with the thickness shown in the product name.

Contact Anglo Stainless for more information

Please call or contact us with your requirements and a member of our team will help you choose between a reduced thickness flange and a full specification one. You can also request our brochure using the form below.