The Toughest Sight Glasses for Manufacturing Sites

Phil Black - PII Editor 15/01/2015

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Sight glasses for manufacturing facilities made from SCHOTT’s BOROFLOAT® specialty glass

Sight glasses, used in manufacturing facilities throughout many industries, enable a safe and undisturbed look into the state of various substances during production. Constant visual observation of the conditions inside pipes and storage tanks ensures processes are working. Thanks to these sight glasses, workers can monitor the material flow and spot any anomalies that could become bigger issues or safety concerns. This is where the international technology group and specialty glass producer SCHOTT comes in: with its BOROFLOAT® borosilicate glass.

The industries in which such sight glasses are used range from oil and gas production to chemical manufacturing up to food and agriculture processing or other growing industries. Besides offering consistent observation, high quality sight glasses made from very robust material, boast an additional advantage: as they are notably reliable, they offer a high level of safety for their users.

Sight glasses must not only provide clear visibility into flow levels, colors, and state changes, but withstand extreme temperatures, pressures, and chemical attacks. The material that makes it possible to peer into pipes and boilers is borosilicate glass, which was developed by Otto Schott, the founder of SCHOTT, in 1887. One of the first applications for borosilicate glass was cylinders in incandescent lighting fixtures, used in early street lights throughout Europe. The material is just as crucial in today’s manufacturing processes due to its unique characteristics.

Its composition allows SCHOTT’s borosilicate glass to resist chemical attacks and more extreme thermal changes, all while maintaining its strength and form. As a result, borosilicate glass has found its way into everything from cookware to the coating of insulator panels on U.S. space shuttles. And despite all of the strength built into this glass, it’s still as clear as any window.

These advances also apply to the production process of borosilicate glass. In 1993, SCHOTT began producing its borosilicate glass in Jena (Germany) using a float manufacturing process, in which molten glass slides over a bath of molten tin and is then homogeneously cooled. This process creates a more uniformly flat and even surface, and the resulting glass product is BOROFLOAT®, one of SCHOTT’s well-known products.

Why BOROFLOAT® is used in oil and gas, chemical production, and food manufacturing

The chemical toughness of BOROFLOAT® comes from one part of its namesake — the element boron. Soda-lime glass, used in many windows and bottles, is mostly composed of sand (silicon dioxide), sodium carbonate, and lime. The chemical makeup of soda-lime glass makes it susceptible to chemical attacks, when elements can be leached out of the glass, weakening or destroying it. But adding appropriate boric components to strengthen the glass’ chemical bonds and prevent leaching makes BOROFLOAT® highly resistant to acids, alkalis, and surface attack due to hydrolysis.

Its chemical structure is also responsible for BOROFLOAT® glass’s high mechanical stability, excellent resistance to abrasion and scratches, high elasticity, and low weight. And the glass’ low coefficient of thermal expansion allows it to stand up to relatively strong thermal shock as well as high or strongly fluctuating temperatures, especially in different sight glass applications. “Due to its unique properties, BOROFLOAT® is the perfect choice for sight glass windows which go into the chemical industry,” says Kathleen Burke Schweizer, Vice President SWIFT Glass.