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METAGLAS® Sight Glasses

Metal fused sight glasses "METAGLAS®" consist of a sight glass that is fused into a steel ring.
The different expansion coefficients of glass and metal cause a compressive stress inside
the glass. The mechanical prestress commands a higher security compared to thermal
prestressed glasses. Because of the mechanical treatment of the steel ring, various
constructive soultions can be realised.

Information

METAGLAS®  Versus Toughened Glass

 

Toughened Glass

Metaglas

Surface

Damage

Damage to the toughened surface can cause unexpected catastrophic failure

 

Scratches or any other surface damage do not affect safety or life of Metaglas

Residual

Stress

Residual stress is created when bolting up. Re-bolting causes excessive residual stress which can lead to failure

 

Repeated re-bolting does not affect Metaglas strenght and integrity.

Pressure

Lower resistance to pressure and catastrophic failure on overpressurisation

 

Higher pressure ratings for similar disc thickness

    

Impact

Impact (mechanical shock) causes catastrophic failure and the glass shatters into a multitude of small fragments

Metaglas has an extremely high resistance to impact. Very high impact may cause local pitting of the glass but this neither affects the the function or its leak tightness

 

BENDING

 

 

Sensitivity

Toughened Glass is very sensitive to uneven torquing of sight port bolts

The glass surfaces must be entirely flat and smooth (within 0.07 mm) to aviod uneven torquing.

Extremely high tolerance to uneven torquing.

Uneven surfaces do not therefore result in glass  damage.

  

Made of Failure

Uneven or over torquing results in the glass cracking right through

Metaglas cannot be overtorqued as you are torquing metal on metal. On reaching the limits of uneven torquing cracks will appear but the Metaglas will remain leak tight

Erosion

Erosion, particulary right through the glass toughened surface, results in significant weakening which can lead to catastrophic failure

Metaglas will remain leak tight to a high level of erosion

Cleaning

Glass must be replaced unless it can be cleaned in-situ

Metaglas lasts indefinitely regardless of how many times you remove, clean and replace it

 

 

The structure of toughened glass is such that any surface damage or stress caused by uneven forces can lead to catastrophic failure. The structure of Metaglas is such that surface damage is limited to local areas and does not affect the overall strength of the glass. Local pitting or cracking may cracking may obscure the view but the glass remains leak tight and secure. Likewise, uneven stresses do not cause Metaglas to fail.