Kapoor Glass (India) Pvt. Ltd. - Product Information - Primary Glass

Technical Terms For Glass

Expansion Coefficient (a) is the average increase in length per unit length per⁰C change in temperature over the range of 30 to 300⁰C.

Density (D) is the weight (W) per unit volume (V) and the values listed are reported in grams per cubic centimeter.
Softening Point is the temperature at which a glass fiber of uniform diameter elongates at a specific rate under its own weight. In this temperature range glass will deform noticeably under its own weight. Softening point temperature corresponds to a viscosity of 10^7.6 poises.
Working Point is the temperature at which the glass has a viscosity of 10⁴ poises. At this temperature the glass is sufficiently soft to be worked.
Annealing Point is the temperature at which the internal stresses caused by rapid cooling or forming temperature may be substantially removed in a matter of minutes.
Chemical durability is the resistance of a glass to chemical attack by its environment. It is expressed by the amount of alkali released.

Technical Terms For Glass Tubings

END FINISH
Definition: Tube is trimmed to specific length and fire polished/glazed to a specific degree.
Fault Definition: If the tube is not glazed as per the standard sample.
AQL:2.5

STRAIN
Definition: Physical stresses of glass tubing are annealed to relieve stress.
Fault Definition: If the tube is not annealed as per the standard sample.
AQL:0.4

AIRLINES
Definition: These are elongated gas bubbles in the tube.
Fault Definition: If the length of broken air line is more than 280 mm/Tube & width is more than 0.1 mm.
AQL:0.4

STONES
Definition: A piece of undissolved or crystallized refractory material, or unmolten batch particle appearing in the glass as an opaque lump.
Fault Definition: Stones with a size more than 0.5 mm
AQL:2.5

KNOTS
Definition: An embedded glassy transparent lump. Knots over 0.5 mm are considered as defects.
Fault Definition: Stones with a size more than 1.0 mm
AQL:2.5

CORDS
Definition: Transparent lines on the tubing. Acceptable limits cannot be felt by touching.
Fault Definition: Cords are not accepted if it is not as per standard sample.
AQL:1.0

TAPER

Definition: The difference between the smallest and the largest diameter on one stick of tube. Taper cannot exceed 40% of the total OD tolerance.

Example:
OD: 15.50 ± 0.20 mm

Taper maximum = ± 0.20 * 0.40 = ± 0.08 mm.

Taper = Diameter_max-Diameter_min

Fault Definition: If the Taper exceed 40% of the total OD tolerance.
AQL:1.0

LENGTH

Definition: Tube length (L) is the distance between both ends of tubing are chill-cut and fire-glazed.

Fault Definition: There is a fault if the Length is out of tolerance.

Maximum Value:1500 ± 05 mm
AQL:1.0

BOW

Definition: Bow (H) is the maximum deviation in horizontal plane of tubing where the central axis of tubing has been permanently deformed over a certain length into the shape of a simple regular curve. It is expressed per 1000 mm length.

Nominal O.D. > 10 mm: H_max 1.0 mm/1000 mm

Maximum Value: H=1.0 mm/1000 m

Fault Definition: If the Bow is more than 1 mm/1000 mm.
AQL:1.0

CRACKS
Definition: Crack is a fracture line without complete separation.
A surface crack in tubing greatly decreases its mechanical strength.
Fault Definition: Cracks longer than 2 mm. that are visible to the unaided eye are not permissible
AQL:1.0

SCRATCHES
Definition: Surface abrasions, which might occur during the manufacturing process or in transit.
Fault Definition: Aggregate length of scratches does not exceed 200 mm per tube.
AQL:2.5

CONTAMINATION
Definition: Stains, dirt or contamination marks that cannot be readily removed, visible with the naked eye, under normal light.
AQL:2.5

OUTSIDE DIAMETER

Definition: The outside diameter (OD) is measured at 2 parallel points on the outside surface of the tube.
The laser precision measuring device checks the outside diameter in one plane over the entire length of each tubing.

Fault Definition: There is a fault if a total piece of 100 mm is out of tolerance over the whole length of the tube.
AQL:0.4

WALL THICKNESS

Definition: The nominal thickness of the glass between the inside and the outside surface of the tube.

Fault Definition: There is a fault if the wall thickness is out of tolerance.
AQL:0.4

OUT OF ROUND (O.O.R)/OVALITY

Definition: The difference (d) between the minimum and the maximum outside diameter made at a cross section of the tube.

TYPICAL TOLERANCES
OUT OF ROUND	OUTSIDE DIAMETER
0.5% of nominal OD	<20 mm
0.7% of nominal OD	20-30 mm

Fault Definition: There is a fault if the O.O.R. is out of tolerance.
AQL:0.4

SIDING

Definition: The difference between the minimum and the maximum wall thickness on a cross section of the tube.

Fault Definition: There is a fault if the Siding is out of tolerance.

Maximum Value
Wall Thickness	Siding
<=0.55 mm	7.5% of the WT
>0.55 mm to < 0.80 mm	7.5% of the WT
>=0.80 mm	7.0% of the WT

MAX WALL

MIN WALL