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Debunking myths about fittings and clamps

December 14, 2005
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Myth:

In almost every case, improper gasket fit is due to over and under-compression of the ferrules.

Fact:

Proper compression for the ferrules is certainly important but not the only gremlin we encounter in clamp applications. Proper gasket fit is also a factor of dimensions, tolerances, clamp efficiencies, gasket material and gasket design. Any one of these can cause improper gasket fit and early failure.

ASME Clamp meets Section VIII Appendix 24 and
is available in sizes from 1" to 12".
Myth:

A true ASME-rated clamp does not exist.

Fact:

This was once a true statement. But L.J. Star now offers a production cast ASME clamp that meets all of the requirements of Section VIII Appendix 24. Primarily used for pressure vessels, filter housings and similar applications, these clamps are available in sizes 1” to 12”. All components of the ASME
Clamp are made of fully traceable 316 Stainless Steel.

Myth:

CE compliant clamps are available only on a custom-production basis.

Fact:

This is old history. Custom-made clamps were once the only way to ensure CE compliance. But today’s standard L.J. Star clamps are also CE compliant, fully meeting the Pressure Equipment Directive 97/23/EC and the Machinery Directive 98/37/EC.

Myth:

All standard 304 Stainless Steel clamps are all, by their nature, immune to rust or rouging.

Fact:

Some 304 stainless steel clamps may seem to be well suited to an application and still present service problems. 304 stainless steel clamps themselves may resist rust and rouging but some include wing nuts that are made of a powdered metal which will rust, especially when autoclaved.

SH Clamp (316 SS) with Ferrules & Gasket
guarantees +/-0.005 Tolerance.
Myth:

Using various sources of supply it is possible to meet most needs for large diameter, schedule pipe, and clamps in various international-standard sizes.

Fact:

Well, yes. One could do that. But a single source is also available. L.J. Star offers tube, schedule pipe, British Standard, DIN, and ISO in sizes up to 12”. (The benefits of schedule pipe clamps over flange connections are lower installation costs, and further savings in lower maintenance and operation costs as well.)

Myth:

304 stainless steel clamps are industry standard for all applications.

Fact:

Almost true. 304 stainless is the industry standard for the majority of applications, but not all. For the exceptions L.J. Star offers a 316 stainless steel clamp. 316 stainless is standard, in fact, on Star’s SH and ASME styles and is an option on all other styles.

SH Clamp (316 SS) with MetaClamp(R) Safety
Sight Glass Window.
Myth:

Size, style and material of construction are the definitive parameters in hygienic clamp selection.

Fact:

These are important specs, yes, but hardly definitive. Hygienic clamp performance varies significantly between available designs. Other important factors in such a clamp’s performance are component dimensions, tolerances, material quality and mechanical design.

L.J. Star hygienic clamps, for example, are made specifically for the pharmaceutical and biotech industries where joint cleanliness and efficiency are of paramount importance. They are made from investment castings to produce a high quality precision fit assembly. The unique groove profile provides higher clamping efficiency and more even compression on the gasket, minimizing bacteria trap.

SSH High Pressure Clamp for Pipe & Tubing Sizes.
Myth:

The 3-Segment Clamp provides a more uniform gasket compression than a 2-segment clamp.

Fact:

Surprisingly, a conventional 3-Segment Clamp actually performs worse than a 2-segment clamp. Studies have shown the middle section of a three-segment clamp acts as a dead leg, providing little compression onto the ferrule. The result is over-compression on two thirds of the gasket and under-compression on one third – providing a place for bacteria to accumulate and grow.

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