The setting gaps used in UltraGrip are to ensure the following does not happen:-
- Maximum insertion depth. This is to ensure that with maximum angular deflection and with the pipe fully expanded due thermal changes, there is no chance of the pipe end coming into contact with the other pipe in the coupling. In the event this occurs then there is a chance of damage to the pipe ends.
- Minimum insertion depth – this is to ensure that again with full angular deflection and with the pipe fully contracted due to thermal changes then there is no chance of the gasket falling off the end of the pipe – i.e. it comes out of the coupling.
Viking Johnson tested many different types of gripping elements during the development of UltraGrip. We found that plastic grippers coated with Aluminium Oxide Grit gave the best results. Metallic grippers rely on penetration of the pipe surface to provide the grip. The amount of penetration varies greatly depending on the pipe material. Therefore, the amount of grip will vary also. The UltraGrip grippers work on friction between the grit and the pipe surface. They are pressed ‘against’ rather than ‘into’ the pipe surface. This gives more consistent gripping performance and also means that the same gripper can be used for all pipe materials.
The AquaFast sealing ring has a double ‘O’ ring design that exerts a very light pressure on the outside of the PE pipe when the product is installed. This pressure is not enough to collapse the PE pipe. The AquaFast gasket is ‘Pressure Responsive’. Pipeline pressure is applied to the back of the gasket to increase sealing as pipe pressure increases.
On the UltraGrip range, full gasket sealing pressure is achieved under bolting. The external loads on the pipe are therefore much higher than those experienced by the AquaFast. These loads would collapse the PE pipe unless a support liner is used.
GSK is an association of Epoxy coating manufacturers. They do not offer approvals for coatings other than Epoxy at the moment.
Ovality is accommodated by variations in the gasket compression around the circumference of the pipe. Because of the thickness of the gasket used on UltraGrip, a maximum ovality of 3mm is possible.
UltraGrip NG is designed and manufactured to have a Design Life Expectancy of 50 years.