So the tubing was installed months ago, and everything is working well. Then you notice fine cracks on the tubing’s exterior where it makes a tight bend before going into a fitting. What are those? How long have they been there? How long till they get worse?

Those are stress cracks, also known as craze, caused by too much tension on the tubing at the bend. Rerouting the tubing or using a more flexible material may avoid the situation.

Problems with tubing, whether they occur during manufacture, storage, or usage, happen. Production difficulties crop up. Products are ordered and then stored at varying temperatures and humidity for years before being needed. Items are used improperly.

Terms used to describe some of the issues that arise include:

Bleed - The diffusion of certain materials from a plastic or elastomeric article such as a color into a surrounding surface caused by the inherent solubility of the ingredient in the material’s composition

Bloom - An undesirable cloudy effect or whitish powdery deposit on the surface of a plastic or elastomeric article caused by the migration of a compounding ingredient such as a lubricant, stabilizer, pigment, plasticizer, etc.

Coil Set - The tendency of a length of tubing or hose to retain a curved form following its post-production coiling

Craze - Minute cracks on the surface of a plastic material

Creep - The permanent dimensional change, with time, of a material under physical load under that material’s limit; creep at room temperature is often called cold flow

Delamination - The separation of layers in a laminate through failure of the resin binder or adhesive

Fish Eye - A small globular mass in a transparent or translucent plastic material caused by the incomplete blending of the mass into surrounding material

Flash - Excess plastic on a molded part which is formed into crevices between mating mold surfaces during the molding operation

Gummy - Sticky, viscid, tacky

Haze - Cloudiness or lack of clarity in a plastic material

Click here for NewAge Industries’ glossary of industry-related terms.

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