When a manufacturer of undersea equipment needed a dependable, capable and reliable assembly solution for its sub-sea isolation valves, it turned to TFC for an answer
A leading manufacturer in the offshore arena needed a deep water isolation barrier valve to isolate reservoirs prior to undertaking works. The operator needed to be sure of completely safe isolation, and this required an increased force in the valve assembly in order to open and close the seal faces of the in-line ball valve which was operating underwater. A lack of both axial and radial space precluded the manufacturer from using conventional disc spring packs (or helical coil springs) so TFC suggested the use of its Smalley Crest-to-Crest® flat wire wave springs as an alternative.
The solution was sound and solved the problem, but because the force required at operating height could not be achieved with a single spring, an interlaced wave spring design was recommended by TFC engineers. The interlaced spring is formed from two or three constituent wave springs of similar thickness, amplitude and frequency combined so that the springs turn about each other for the entire length of the spring. The interlacing effectively increases the thickness of the flat wire section and thus provides increased loading capability.
In the hostile environment in which the springs would be operating, the potential existed for very high temperatures to be reached, and this, combined with the additional possibility of exposure to sour gas, salt and seawater, meant that Inconel X-750 material was chosen for the application. Inconel has a high resistance to corrosion and also offers a reasonably high tensile property says TFC. This allowed TFC’s engineers to solve the customers’ corrosion challenge whilst keeping the spring close to the same size as that which a ‘standard material’ alloy spring would be.
Thanks to the combination of features offered by the TFC Smalley interlaced spring, the customer was able to improve the sealing efficiency of the valve despite the incredibly tight space constraints demanded by the design, thanks to the narrow wall section of the TFC Smalley spring.