Machine Design

Polymer springs into action

Energy absorbing springs used in seal and backup rings for the oil and gas industry were historically made from ferrous metals. Problem is, over time the metals not only corrode but also score the backup ring shaft as the seal wears away.

A new line of non-metallic PEEK polymer energy absorbing springs from Clifford Spring Co. in England overcomes these problems. Victrex PEEK polymer from Victrex USA Inc. is strong and stands up to aggressive chemicals, solvents, and lubricants. It is also not abrasive enough to score the backup ring shafts. PEEK is light in weight, has a coefficient of thermal expansion similar to that of the seal material, and can be manufactured as a totally encapsulated item — this prevents the seal from lipping out and prolongs seal life.

The polymer can also be used for Garter springs added as a secondary operation, following molding or machining of the seal. PEEK Garter springs can be color-coded for instant identification and assurance that the correct energy absorber is fitted to the seal. Energy absorbers made from PEEK are available with outside diameters of 1.4 up to 10 mm (0.05 to 0.394 in). The maximum single length that can be produced is 2.4 m (7.9 ft). This equates to a spring diameter of approximately 75 cm (2.5 ft). Multiple springs can be joined end to end to give a larger spring diameter.

More Information:
Clifford Spring Co.
Victrex USA Inc.

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