Pipe, Pump, Values: Walform M Plus : Leak Free pipe connections
The Walform M Plus pipe connector system developed by GKN Walterscheid in Germany and marketed exclusively in Great Britain by Stauff UK is designed to deliver a new dimension of safety and reliability to pipework systems for British Warships.
There were opportunities to introduce the latest connection technology for future builds, that would provide significant performance improvements as well as cost reductions. Therefore the MoD (Navy) with Stauff and Walterscheid at Qinetic in Rosyth entered into the most exhaustive test program ever carried out on pipe work couplings by the M.o.D. At the end of the program Walform M was given full M.o.D. (Navy) approval for use on Cupro - Nickel 70 / 30 pipework for all future work.
The Components
The Walform M Plus connector system uses standard DIN 2353 connector components i.e. malestuds, elbows, straight connectors etc.; but does not utilize the cutting ring (olive). Instead the tube is reshaped on the Walform machine to replicate the 24-degree cone. This eliminates any potential for a leak path to be created in conditions of severe stress. The Walform Plus System has two versions: the M (metallic) seal or the WD (elastomeric seal). The latter provides for sealing to be enhanced with the use of a separate and replaceable profiled sealing ring. This is an additional feature that can be used when there is no inherent worry about the inclusion of polymer products.
Testing
A whole series of tests were undertaken: Proof Pressure: Disassembly/Reassembly; Vacuum Gas; Maximum Static Gas; Impulse; Vibration; Thermal Cycle; Fire Test; Overtighten Test; Tensile Test; Deck Shock; and Shock Test.
Probably the most significant of these was the shock test program, brief details of which are as follows:
A sample cross section of pipes were made up using 70/30cupro nickel tube and fitted with straight connectors and elbows. These pipes were then fitted to deck shock test equipment, pressurised to 300 bar and subjected to 100g acceleration with maximum deflection (63.5mm). Then they were further fitted to shock test machines, pressurized to 300 bar and subjected to acceleration in both the vertical and horizontal axes, of firstly 200g - the required level for MOD acceptance, and in addition further tests up to 700g were successfully carried out. At the completion of the testing program, despite considerable distortion of the pipework, including bending of the 38 mm dia. x 6.5 mm wall tube, all of the joints maintained a completely leak free integrity.
Application
For Warship and other military uses, the application of systems with a metal seal helps to avoid any of the operational problems sometimes associated with the long-term lay-up of joints with polymer seals.
The introduction and application development of this system has been carefully scrutinized by UK Defense departments and their contractors. The need for defense project suppliers to offer whole life guarantees and support for their equipment means that the long-term integrity offered by Walform M Plus will provide service life cost savings as well as initial installation cost reduction.
Because this system has been developed essentially as a commercial product, there are no premiums involved when using it for pipework systems at large. This means that the use of the Walform product in everyday applications will offer huge benefits in terms of operating features. The inherent leak free properties as well as high operating pressures will ensure long life and minimum service costs.
