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Sanitary Fittings: How to properly install ferrule clamp unions.

Updated: Oct 2, 2023

Ferrule Clamp Union installation
Installing Clamp Unions

In sanitary process systems, improper material installation can cause bacteria to harbor, and leakages. And if product can get out, contaminants could also get in, potentially leading to an entire batch of product to be rejected.

In the Malaysia food and beverage manufacturing industry, sanitary fittings such as ferrule clamp unions are often disassembled for cleaning and maintenance. This increases the chances of improper reassembly.

ferrule clamp union supplier
Parts of a clamp union

Clamp Union Construction

Clamp Union connections consists of two ferrules, a clamp ring, and a gasket. When installed properly, the clamp ring secures two ferrules with the gasket sitting in between, without creating an pockets where product can collect.

Like most sanitary fittings. The ferrules come in SS 304 or SS 316L, and there are a variety of gasket material to choose from. Sizes range from 0.5" to 12".

Inspect Clamp Union

Before installation visually inspect the gaskets and ferrules.

1) The surface of the ferrules should be free of imperfections such as scratches or gouges where bacteria can grow.

2) Any product or gasket residue should be removed from the ferrule surface. An uneven surface can cause the gasket to not sit properly leading to growth of bacteria.

3) The surface of the gasket should not have imperfections such as cracks, tears, or product residue.

4) If an elastomeric gasket is used (flexible, rubberlike material), check its flexibility as it hardens over use and time. It should not crack when it is bent.

Clamp Union Installation

During installation, it is important to make sure the ferrules are aligned before clamping. The clamp ring should not be used to forcefully pull tubing and ferrules into alignment.

Ferrule welding
Misaligned ferrules

Another type of misalignment is where one side of the gasket is compressed much more than the other, potentially leaving a gap on one side.

Clamp union welding
Misaligned ferrules 2

Under tightening the clamp rings might leave dangerous gaps and cause leakages and bacterial growth.

Ferrule Gasket
Clamp union under tightening

Over tightening the clamp rings will cause the gaskets to over compress, and there will be an intrusion of the gasket into the flow of the product. Over tightening will not lead to leaks but blockages and bacterial growth might occur.

Clamp union gasket
Clamp union over tightening


To know more about our clamp unions, head over to our clamp union page.

NKE Flow is a supplier of Sanitary fittings, tubes, and valves, but we do not provide installation services. But should you be in need of a reliable installer, let us know, we will be more than happy to point you to one of the fabricators we work with.


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