Typical Geometrical Characteristics of fused silica tubes

We at Heraeus have been dealing with tubes for a long time. Over the years we have developed our own vocabulary when taking about the geometric properties of tubes. Not all might be intuitively understood, therefore, we try to visualize them for you below. Please note, that not all properties are part of a specification, but they might be and tolerances are a key factor in determining the price of your product. For an overview of the available tubes check out our  product pages .


Outer Diameter (OD)

OD tolerance

Outer Diameter Tolerance

Maximum deviation of real OD from nominal OD in mm.


Inner Diameter (ID)

ID tolerance

Inner Diameter Tolerance

Maximum deviation of real ID from nominal ID in mm.

wall thickness

Wall Thickness (WT)

wall thickness tolerance

Wall Thickness Tolerance

Maximum deviation of real WT from nominal WT in mm.



Maximum wall thickness minus minimum wall thickness in mm.



Difference of Maximum OD and minimum OD at one ring in mm.



Maximum displacement of tube center when both ends are on the axis of rotation in mm.

CSA variation

Cross Sectional Area (CSA) variation

Variation of CSA in one tube: Difference of Max. and Min. CSA normalized to avg. CSA of tube in %.