A glass tube for pharmaceutical containers is provided. The tube has an inner surface at an inner diameter, an outer surface with an outer diameter, a first end defining a first closed end, a second end defining a first closed end, a first location 400 mm from the first end, a first intermediate location 15 mm from the first end, and a ventilation hole at a first vicinity. The first vicinity is between the first intermediate location and the first location. The glass tube can have a ratio of an integrated Na.sub.2F.sup.+ signal to an integrated .sup.30Si.sup.+ signal of at least 0.10, where the integrated Na.sub.2F.sup.+ signal and the integrated .sup.30Si.sup.+ signal are integrated over a depth of 100 nm. The glass tube can have a ratio between a fluorescence emission determined at a first vicinity and a fluorescence emission determined at a middle section of at least 0.6.

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 5×10.sup.−7/° C. to about 100×10.sup.−7/° C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200° C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50° C. to about 200° C. of each other.

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 5×10.sup.−7/° C. to about 100×10.sup.−7/° C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200° C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50° C. to about 200° C. of each other.

A submerged combustion melter is arranged with a melting chamber, which may be cylindrical, and at least five submerged combustion burners.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

An apparatus (100) for making glass tubing (200) of a desired non-circular cross-sectional profile (cf FIG. 3) includes a mandrel (101) adapted for positioning proximate heat-softened tubing. The mandrel (101) has a nose (102) and a nozzle section (120) with a chosen profile that will define a final cross-sectional profile of the tubing. The nozzle section (120) has a feed chamber (140) for receiving a gas from a source (207) and a porous and/or foraminous circumferential surface (132,134) through which the gas can be discharged to an exterior of the mandrel. The gas discharges to the exterior of the mandrel, forming a film of pressurized gas in the gap (314, 318) between the porous circumferential surface (132,134) and the heat-softened tubing (200). A method of forming tubing having a non-circular cross-sectional profile using the apparatus is also provided. A glass sleeve made from the reshaped or formed tubing is also disclosed: a monolithic sleeve made of parallel, opposite, flat and smooth front and back covers for use in an electronic device (cf FIG. 13). Some glass-ceramic materials may also be suitable for the tubing, such as transparent beta spodumene.

A glass tube manufacturing apparatus for manufacturing glass tubing includes a glass delivery tank with molten glass. The glass delivery tank has a bottom opening. A bell has an upper portion with an outer diameter located at the bottom opening. A heating apparatus is at least partially disposed around the bell. The heating apparatus includes a heated portion and a muffle portion located below the heated portion. A lower extended muffle structure extends downwardly from the muffle portion. The lower extended muffle structure extending about the glass tubing on all sides to manage convective airflow therethrough.

A glass tube manufacturing apparatus for manufacturing glass tubing includes a glass delivery tank with molten glass. The glass delivery tank has a bottom opening. A bell has an upper portion with an outer diameter located at the bottom opening. A heating apparatus is at least partially disposed around the bell. The heating apparatus includes a heated portion and a muffle portion located below the heated portion. A lower extended muffle structure extends downwardly from the muffle portion. The lower extended muffle structure extending about the glass tubing on all sides to manage convective airflow therethrough.

Heating apparatuses and methods for glass tubing manufacturing are disclosed. A heating apparatus for glass tubing manufacturing includes a bowl configured to receive molten glass and a plurality of heating elements thermally coupled to the bowl. The bowl has a bowl height and includes a tub portion configured to hold the molten glass, a bowl well extending beneath the tub portion, and an orifice at a distal end of the bowl well. The plurality of heating elements include a first heating element disposed at a first vertical location along the bowl height, a second heating element disposed at a second vertical location along the bowl height, wherein the first vertical location is vertically spaced apart from the second vertical location.

Heating apparatuses and methods for glass tubing manufacturing are disclosed. A heating apparatus for glass tubing manufacturing includes a bowl configured to receive molten glass and a plurality of heating elements thermally coupled to the bowl. The bowl has a bowl height and includes a tub portion configured to hold the molten glass, a bowl well extending beneath the tub portion, and an orifice at a distal end of the bowl well. The plurality of heating elements include a first heating element disposed at a first vertical location along the bowl height, a second heating element disposed at a second vertical location along the bowl height, wherein the first vertical location is vertically spaced apart from the second vertical location.