3A vs DIN Tri-Clamp Fittings – Same Clamp, Different Tube Sizes

In many catalogues everything is just called “1.5" Tri-Clamp” and that’s it.
On the shop floor it is not that simple.

You clamp two ferrules together – they seal, the gasket fits, everything looks fine.
Then you check the weld from the inside and see a small step in the bore, or you notice that one line is built from 38 mm tube and another from 41 mm, although both were sold as “1.5" Tri-Clamp”.

Historically the split was clear:

• 3A / ASME BPE sanitary tubing in the US and pharma,

• DIN / EN hygienic tubing in Europe.

Today the reality is much more mixed. A large share of stainless steel fittings in Europe now comes from suppliers who follow 3A-style / ISO clamp dimensions and combine them with different tube series. That includes the fittings we supply on our internet shop: they are based on 3A dimensions up to 4" and are widely used in European food and beverage plants alongside DIN tube.

This guide explains what “3A Tri-Clamp” and “DIN Tri-Clamp” actually mean, using real tube dimensions (OD and ID) so you can see why “1.5 inch” is not always the same thing – especially when you start mixing 25, 32, 38 and DIN sizes in one system.

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1. What do we really mean by “3A Tri-Clamp” and “DIN Tri-Clamp”?

First, a quick clarification.

Tri-Clamp (Tri-Clover) describes the connection:

• two ferrules with flat flanges,

• a gasket between them,

• and a clamp that presses the flanges together.

Different standards then define:

• flange dimensions,

• surface finish and hygiene requirements,

• and which tube series these ferrules are welded to.

3A side – the fittings I supply

On the 3A side you typically see imperial sanitary tube sizes:

• 1", 1.5", 2", 3", 4"…

with fixed outer diameters (OD):

• 1.5" → OD = 38.1 mm

• 2" → OD = 50.8 mm

• 3" → OD = 76.2 mm

• 4" → OD = 101.6 mm

In practice, for process lines up to 4" most suppliers in Europe and China (including me) use about 1.5 mm wall thickness as a de-facto standard. That gives you a 1.5" 3A tube with a bore around 35 mm.

Ferrules and tubes in this family are designed to follow 3A Sanitary and ASME BPE / ASTM A270 requirements: weldability, cleanability, defined OD and wall thickness and a hygienic surface finish.

When I write “3A 1.5" Tri-Clamp fitting” in my shop, I mean:

A Tri-Clamp ferrule with a standard clamp flange, welded to 1.5" sanitary tube (38.1 mm OD, ≈1.5 mm wall), compatible with 3A-style hygienic tube.

DIN side – the original European metric series

On the DIN side the tube is metric and defined as DN:

• DN25, DN32, DN40, DN50, DN65, DN80, DN100…

Each DN has its own OD and typical wall thickness. For example:

• DN40 → OD ≈ 41.0 mm, wall ≈ 1.5 mm → ID ≈ 38 mm

• DN50 → OD ≈ 53.0 mm, wall ≈ 1.5 mm → ID ≈ 50 mm

The matching clamp-type ferrules are defined in DIN 32676, which ties clamp flange sizes to these DIN tube series.

So when someone says “DIN DN40 Tri-Clamp”, they usually mean:

A Tri-Clamp-style ferrule according to DIN 32676, welded to DIN hygienic tube (for example DN40: ~41×1.5 mm).

Key point so far

• On the outside, 3A and DIN ferrules for “1.5" / DN40” can share the same clamp flange diameter (so the clamp and gasket are the same).

• On the inside, they are welded to different tube series – 38.1 mm OD for 3A, ~41 mm OD for DIN.

Unsurprisingly, that difference shows up in the weld and in the flow.

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2. The classic comparison: 1.5" 3A vs DN40 DIN

(and where 25 mm and 32 mm come into the picture)

Let’s start with the combination you see almost every day: 1.5" Tri-Clamp.

1.5" in the 3A world

A typical 3A 1.5" process tube:

• OD = 38.1 mm

• Wall ≈ 1.5 mm

• ID ≈ 38.1 – 2×1.5 ≈ 35.1 mm

So a 1.5" 3A line has a bore of roughly 35 mm.

DN40 in the DIN world

A typical DIN DN40 tube:

• OD ≈ 41.0 mm

• Wall ≈ 1.5 mm

• ID ≈ 41.0 – 2×1.5 ≈ 38.0 mm

A DN40 line therefore has a bore of about 38 mm.

How they actually fit together

Now put a piece of 1.5" 3A tube next to a piece of DN40 tube.

• 3A 1.5" tube: 38.1 mm OD

• DN40 tube: ≈38 mm ID

If you try it in the workshop, the 3A tube will slide neatly inside the DN40 tube. The fit is surprisingly close – close enough that it is tempting to weld them together.

From a standards point of view, however:

• the smaller 3A tube becomes a kind of inner sleeve,

• the larger DIN tube becomes a socket.

There is no “official” joint like this in 3A or DIN tables, it is simply what happens when the two systems meet.

If you butt-weld them directly, you almost always end up with a step in the bore. That step is small, but it is real: it affects flow and cleaning and is exactly the kind of detail that never shows up on the sales drawing labelled “1.5" Tri-Clamp”.

And then there are 25 mm and 32 mm “1.5 inch” lines

In real installations you will also see 25 mm and 32 mm tube welded to 1.5" Tri-Clamp ferrules:

• 1.5" clamp ferrule on 25×1.5 mm tube → ID ≈ 22 mm

• 1.5" clamp ferrule on 32×1.5 mm tube → ID ≈ 29 mm

Machine builders like these combinations on:

• small filling lines,

• CIP return lines,

• sampling and utility lines,

because the 1.5" clamp hardware (50.5 mm flange) is cheap and universal, while the tube OD is chosen just for the required flow.

These 25 mm and 32 mm “1.5 inch” solutions do not belong to 3A or DIN hygienic tube series in the strict sense. They are practical hybrids: “whatever clamp size the factory uses” + “whatever metric tube was convenient”.

The result is that under the same label “1.5" Tri-Clamp” you can meet at least four different tube bores:

• ~22 mm (25 mm tube),

• ~29 mm (32 mm tube),

• ~35 mm (1.5" 3A tube),

• ~38 mm (DN40 tube).

Which brings us to the clamp flange itself.

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3. Where 3A and DIN really match: the Tri-Clamp ferrule flange

Up to now we looked at tube OD and ID.
The ferrule flange is the part that actually sees the clamp and gasket.

For the most common process sizes, 3A / ISO / ASME BPE and DIN 32676 use very similar clamp flange diameters:

• 1.5" / DN40 → flange OD around 50.5 mm

• 2" / DN50 → flange OD around 64 mm

• 3" / DN80 → flange OD around 91 mm

• 4" / DN100 → flange OD around 119 mm

This is why, in practice, you can:

• take a 3A 1.5" ferrule on 38.1 mm tube,

• take a DIN DN40 ferrule on ~41 mm tube,

• put a standard 1.5" clamp and gasket between them,

and the joint will seal and work.

From the outside everything looks compatible: “same clamp, no leaks, all good”.

From the inside, the situation is less tidy:

• the clamp flange is standardised and compatible between the systems,

• the tube series behind the flange is different and can create:

  • a step in the bore,

  • a small pocket where product can sit,

  • different flow velocities at the same volumetric flow.

So a practical summary for the reader:

If two ferrules close with the same 1.5" clamp, they are “Tri-Clamp compatible” at the flange.
If the tubes behind them come from different families (3A 38.1 mm, DIN 41 mm, or 25 / 32 mm hybrids), they will not be the same line internally.

Tri Clamp Dimensions & Sizing Guide

Tri Clamp fittings (also known as Tri Clover or sanitary fittings) are widely used in food, beverage, pharmaceutical and biotech applications. This guide explains how Tri Clamp sizing works and shows a dimension table based on the 3-A Sanitary (OD-tube) standard, which is also used by most modern European and Chinese manufacturers.

1. How Tri Clamp Sizes Are Defined

Nominal Tri Clamp sizes are based on the outer diameter (D1) of the tube (for example 1.5" OD tube), not on the clamp or ferrule outside diameter.

2. What Makes a Complete Tri Clamp Connection?

A complete Tri Clamp connection consists of:

• Two ferrules (welded or otherwise attached to the tubing)
• One clamp (that closes around the ferrule flanges)
• One gasket (between the ferrules, providing the seal)

All parts must be the same Tri Clamp size (for example 2") so that the ferrule OD, clamp and gasket match.

3. How to Measure Tri Clamp Components

• Tube (D1, D2): D1 is the tube outer diameter (nominal size). D2 is the typical tube inner diameter for the given wall thickness.
• Ferrule: Measure the ferrule outside diameter (clamp flange). This tells you which clamp and gasket series you need (25.4 mm, 34 mm, 50.5 mm, 64 mm, 77.5 mm, 91 mm, 106 mm, 119 mm, 167 mm, 217.7 mm, etc.).
• Clamp: The clamp is selected by the ferrule OD, not by tube size directly.
• Gasket: Choose the gasket by the same ferrule OD. For hygienic processes it is good practice to select a gasket whose inner diameter is close to the tube ID (D2), especially for sizes that are used with several tube wall thicknesses.

4. Tri Clamp Size Chart (3-A Based)

The image below shows how the dimensions correspond to the Tri Clamp ferrule.

The table below lists common Tri Clamp sizes and typical dimensions. Ferrule OD values follow the 3-A / ASTM A270 Tri Clamp connection standard; tube IDs (D2) are typical values and may vary slightly between manufacturers. In our internet shop you also mainly will find fittings based on  3-A / ASTM A270 standart.

Nominal size in inches	Nominal size in mm	Ferrule OD	D1	D2
1/2"	12.7mm	25.4mm	12.7mm	9.7mm
3/4"	19mm	25.4mm	19mm	16mm
3/4"	19mm	34mm	19mm	16mm
1/2"	12.7mm	50.5mm	12.7mm	9.7mm
3/4"	19mm	50.5mm	19mm	16mm
1"	25mm	50.5mm	25.4mm	22.4mm
1 1/4"	32mm	50.5mm	31.8mm	28.8mm
1 1/2"	38mm	50.5mm	38.1mm	35.1mm
1 3/4"	45mm	64mm	45mm	42mm
2"	51mm	64mm	50.8mm	47.8mm
2 1/2"	63mm	77.5mm	63.5mm	59.5mm
3"	76mm	91mm	76.2mm	72.2mm
4"	102mm	119mm	101.6mm	97.6mm
5"	127mm	144.5mm	127mm	120mm
6"	152mm	166.7mm	152.4mm	147.4mm
6 1/2"	159mm	183mm	159mm	153mm
8"	204mm	217.7mm	203.2mm	196.7mm
10"	254mm	268mm	254mm	250mm

Note: 1/2" and 3/4" tube sizes appear with several ferrule ODs (25.4 mm, 34 mm, 50.5 mm). Choose the version that matches the clamp size already used in your system.

5. Practical Sizing Tips

• Always confirm the ferrule OD with a caliper before ordering new clamps or gaskets.
• When mixing components from different suppliers (EU, US, China), use 3-A based dimensions (as in this table) as the reference.
• Use reducers if you need to connect different tube sizes but want to keep the same clamp size.
• For hygienic applications, match gasket ID as closely as practical to tube ID to minimise dead zones.

The Ultimate Guide to Butterfly Valves vs Ball Valves in Brewing: Which is Best for Your Brewery?

When it comes to brewing, the equipment you use can significantly impact the efficiency and quality of your production. Two common types of valves used in the brewing industry are butterfly valves and ball valves. Both have their own unique advantages and applications, and understanding these can help you make an informed decision for your brewery. In this ultimate guide, we'll explore the differences between butterfly valves and ball valves, focusing on their applications, hygiene, cleaning, and other relevant factors to help you choose the best valve solution for your brewery.

Applications in Brewing

Butterfly Valves:
Butterfly valves are widely used in brewing due to their compact design and ease of operation. They are particularly suitable for applications where space is limited and where quick, frequent operation is required. These valves are excellent for controlling the flow of liquids in processes such as transferring wort, water, and cleaning solutions. Their simple design makes them ideal for use in various stages of brewing, from the mash tun to the fermenter.

Ball Valves:
Ball valves are known for their durability and tight sealing capabilities. They are often used in situations where a complete, leak-proof shut-off is required. In brewing, ball valves are typically used in high-pressure applications and where precise control of the liquid flow is crucial. They are commonly found in systems dealing with carbonation, yeast propagation, and other areas where maintaining pressure integrity is essential.

Cleaning and Sanitation of Brewing Valves

One of the primary differences between ball valves and butterfly valves is their ease of cleaning and sanitation. Butterfly valves are easier to clean and sanitize compared to ball valves. The flat disc design of butterfly valves allows for better cleaning in place (CIP), reducing the need for disassembly. A commercial brewery even had to make a sour beer due to contamination from a ball valve, which was then replaced with a butterfly valve. This incident highlights the importance of valve design in maintaining hygiene in the brewing process.Ball valves, on the other hand, have more crevices where gunk can accumulate, requiring disassembly for thorough cleaning. While many ball valves designed for the brewing industry come with features that facilitate easier cleaning, such as full port designs and sanitary fittings, they still pose a higher risk for contamination if not properly maintained.

Flow Obstruction and Pressure Drop in Brewing Valves

Ball Valves:
Ball valves have an unobstructed flow path when fully open, which allows for smooth liquid transfer without any resistance. This design feature makes ball valves highly efficient for applications requiring a free-flowing stream. Due to their unobstructed flow path, ball valves tend to have a lower pressure drop compared to butterfly valves. This characteristic makes them suitable for applications where maintaining pressure is critical.

Butterfly Valves:
Butterfly valves have a stem running through the middle, causing some obstruction in the flow path. However, this obstruction is minimal and does not significantly impact the performance of the valve in most brewing applications. Despite this, butterfly valves are still widely used in breweries due to their other advantages. While butterfly valves do cause a slight pressure drop due to the central stem, this drop is generally not substantial enough to affect the overall brewing process. The trade-off is considered acceptable given the other benefits butterfly valves offer.

Viscosity Handling and Cost Considerations in Brewing Valves

Butterfly Valves:
Thicker mediums like wort can cause buildup in butterfly valves due to the stem, which can obstruct the flow and lead to potential maintenance issues. Brewers need to ensure regular cleaning and inspection to prevent such buildup. Butterfly valves are generally more expensive than ball valves of the same size. However, the higher cost is often justified by their ease of cleaning, hygienic design, and overall efficiency in brewing operations.

Ball Valves:
Ball valves handle viscous fluids better as they provide a clear, unobstructed path when open. This makes them a preferable choice for handling thicker liquids without the risk of clogging. Ball valves are typically less expensive, making them an attractive option for brewers on a budget. However, the potential for higher maintenance costs and the risk of contamination might offset the initial savings.

Conclusion

In summary, while ball valves have some advantages, butterfly valves are preferred in breweries for their ease of cleaning, good sanitary design, and adequate flow control, despite the slightly higher cost. Many brewers, both commercial and homebrewers, have transitioned to using butterfly valves throughout their systems. Choosing between butterfly valves and ball valves for your brewery depends on your specific needs and preferences, but understanding these differences can help you optimize your brewing process.At our store, we offer a wide range of high-quality butterfly valves and ball valves to meet your brewing needs. Contact us today to find the perfect valve solution for your brewery and take your brewing operations to the next level.

Brewery Hose Connections: Crimped vs. Clamp/Barb

Maintaining Hygiene:

Flawless hygiene is crucial for breweries. Selecting the right hose connection method significantly impacts cleanliness, sanitation, and ultimately, product quality. This article compares crimped hose ends and hose clamp/barb connections specifically for breweries, where hygiene is paramount.

Crimped Hose Ends: Secure and Sanitary

Crimped connections offer a permanent seal between the hose and fitting, eliminating gaps and potential contamination points. This minimizes leaks and ensures a smooth, hygienic connection throughout the brewing process. Their smooth finish simplifies cleaning and sterilization, vital for brewery environments.

Advantages of Crimped Ends:

• Superior Sanitation: Permanent seals minimize bacterial growth and contamination risks.
• Leakproof Reliability: Crimping reduces leaks, ensuring consistent performance.
• Easy Cleaning: Smooth surfaces facilitate cleaning and sterilization, supporting strict hygiene practices.

Clamp/Barb Connections: Convenience vs. Hygiene

While less inherently sanitary than crimped ends, hose clamp/barb connections remain popular due to their flexibility and ease of use. This method allows for quick assembly and adjustments during setup changes. However, maintaining acceptable hygiene levels requires regular inspections and proper maintenance.

Hygiene Considerations for Breweries:

• Contamination Risk: Crimped ends offer a lower risk due to their secure seal.
• Long-Term Performance: Crimped connections require less maintenance and offer consistent performance over time.
• Regulations: Many breweries face strict hygiene and food safety regulations, making crimped ends a compliant solution.

The Hygienic Choice:

For breweries prioritizing top-level hygiene, crimped hose ends are a strategic investment. They provide a reliable, long-term solution that aligns with regulations and promotes optimal brewing conditions. While clamp/barb connections offer convenience, they demand constant monitoring to maintain acceptable hygiene levels.

Conclusion:

Crimped hose ends are the preferred choice for breweries with uncompromising hygiene standards. By prioritizing sanitation and investing in quality connections, breweries safeguard product integrity and maintain a reputation for excellence.

Benefits of Triclamp Connection Fittings in Breweries

Benefits of Triclamp Connection Fittings in Breweries

Cost Efficiency: Triclamp connection fittings offer a compelling cost-effective solution for breweries, primarily due to their efficient use of resources. Unlike other connection types, such as DIN 18851, which may require a larger variety of sizes to accommodate different equipment, triclamp fittings can often cover a broader range of applications with fewer variations. This means breweries can streamline their inventory management and reduce the number of different sizes of connections needed, ultimately saving on procurement costs and minimizing inventory overhead.

Sanitary Design: Triclamp fittings are designed to meet strict sanitary standards, making them ideal for use in breweries where cleanliness is paramount. Their smooth surface finish and crevice-free design minimize the risk of bacterial growth and contamination, ensuring the integrity of your brew.

Easy Installation and Removal: The simple yet effective design of triclamp fittings allows for quick and hassle-free installation and removal. With just a few twists of a clamp, you can securely connect or disconnect brewery components, saving time and effort during equipment setup and maintenance.

Versatility: Triclamp fittings come in a wide range of sizes and configurations, making them highly versatile for various brewery applications. Whether you're connecting pipes, transferring liquids, or assembling equipment, triclamp fittings offer the flexibility to adapt to your specific needs.

Leak-Proof Seal: One of the key advantages of triclamp fittings is their ability to create a tight and leak-proof seal. The combination of a high-quality gasket and a secure clamp ensures that connections remain sealed under pressure, minimizing the risk of costly leaks and downtime.

Durable Construction: Built to withstand the rigors of brewery operations, triclamp fittings are constructed from durable materials such as stainless steel. This ensures long-lasting performance and reliability, even in harsh brewing environments.

Upgrade Your Brewery with Triclamp Connection Fittings

Triclamp connection fittings offer a host of benefits that can enhance efficiency, sanitation, and overall brewing quality while remaining cost-effective. By minimizing the need for a wide variety of connection sizes and ensuring a reliable, leak-proof seal, triclamp fittings provide breweries with a cost-efficient solution for their brewing equipment needs.

Understanding the Differences: DIN 18851 Fittings vs. Tri-Clamp Fittings

Sanitary fittings are an essential component in industries where hygiene and cleanliness are critical, particularly in food, beverage, pharmaceutical, and biotech applications. Two widely used types of sanitary fittings are DIN 18851 and tri-clamp fittings. While they share similarities in function, there are crucial distinctions to understand when choosing the right fittings for your system.

What are DIN 18851 Fittings?

• Originate from the German Institute for Standardization (DIN) standards.
• Primarily used in European countries.
• Designed for metric measurements (millimeters).
• Measured based on the inside diameter (ID) of the tube.

What are Tri-Clamp Fittings?

• Also known as Tri-Clover fittings, named after the original manufacturer.
• Predominantly used in North America.
• Designed for imperial measurements (inches).
• Measured based on the outside diameter (OD) of the tube.

Key Differences

Let's break down the main differences between DIN 18851 and tri-clamp fittings:

• Measurement Systems: The core distinction lies in how they're measured. DIN fittings use the metric system, while tri-clamp fittings use the imperial system.
• Sizing: Due to different measurement standards, even similarly labeled sizes (e.g., DIN 50 and 2-inch tri-clamp) won't be a perfect match in terms of diameter.
• Sealing Mechanism:
  • DIN 18851 often incorporates a gasket and a male and female connection that secures tightly using a nut and liner.
  • Tri-clamp fittings use a gasket compressed between two ferrules, held together by a clamp.
• Interchangeability: In smaller sizes, tri-clamp and DIN fittings might be interchangeable, but it's important to verify exact dimensions to ensure a proper seal.

Which One Should You Choose?

The best choice often depends on these factors:

• Regional Standards: Consider the prevalent fitting standards in your location. This ensures easier compatibility and parts availability.
• System Specifications: If you're integrating into an existing system, verify the existing fitting type to maintain consistency.
• Specific Requirements: Consider pressure ratings, temperature tolerances, and any special material needs for your application.

In Conclusion

Both DIN 18851 and tri-clamp fittings provide reliable and hygienic connections in sanitary environments. Understanding the differences in measurement, sizing, and sealing mechanisms is crucial for selecting the most suitable fittings for your process needs.