Tungum Alloy Tube

Tungum Alloy (Aluminium-Nickel-Silicon-brass) combines an unusually high strength to weight ratio, with ductility, excellent corrosion resistance, and first class fatigue properties.

Highly resistant to sea water and its atmosphere, Tungum resists both stress and crevice corrosion to offer outstanding serviceability, even at intermittent duty in the highly corrosive ‘splash’ zone.

Non-magnetic and non-sparking properties make Tungum invaluable in piping high pressure gases, particularly oxygen where its thermal conductivity/ defusivity characteristics virtually eliminate the potential dangers present when lesser materials are employed.

Tungum Alloy is a cryogenic material, suitable for chemical engineering and low temperature processes. Its corrosion resistance often enables its use in conveying fluids and gasses containing corrosive elements.

Tungum is uncommon among copper alloys, in that heat treatments include precipitation hardening. This enables its physical properties to be increased or decreased as required, to suit your circumstances.

Tungum’s high proof to ultimate stress ratio enables system proof tests to be conducted well above working pressure, without risk of permanent set taking place.

When used in high pressure hydraulic or pneumatic circuits, these features together with inherent “clean bore” characteristics combine in affording an easily constructed, high integrity system. This requires a minimum of purging and no external protective treatment.

Pages 6 & 7 illustrate just some of the many applications where a requirement for a tube exists, that has to be strong, capable of absorbing vibration, be resistant to corrosion and yet still bent into a complex shape. This has been more than satisfied by the use of Tungum Alloy.

Some offshore installations currently utilizing TUNGUM alloy corrosion-resistant tubing.

  • Britoil ‘Clyde’ Platform
  • Total ‘Dunbar’ Platform
  • E.E. Caledonia ‘Piper Bravo’ & ‘Saltire’ Platforms
  • B.P. ESV “Iolair’, ‘Sullean’ & ‘Buzzard’ Platforms
  • Houlder Offshore MSV ‘Uncle John’
  • Q.G.P.C. ‘North Field’ Platform
  • Texaco ‘Captain’ Platform & Floater
  • Shell has standardised on TUNGUM for - ‘Eider’, ‘Tern’, ‘Southern Basin Revamp’, ‘Sole Pit MSV’, ‘Stadive’, ‘Golden Eye,’ ‘Sakhalin Isle’ & ‘Ursa’ in the Gulf of Mexico

In salt-laden marine atmospheres, ‘316’ stainless steel is highly susceptible to crevice corrosion and chloride pitting. After just a few years of salt spray exposure, it may still look bright from a distance, but closer inspection reveals telltale signs of imminent failure to hold pressure.

Tungum alloy, however, possesses a natural protection mechanism whereby, on exposure to salt spray, a very thin oxide coating is generated over the exposed surface, no more than two thousandths of an inch thick, when complete. The tube becomes discoloured, it may even have a verdigris coating, but under the oxide layer the tube material is perfect and will remain so for a very long time.

Tungum has been in use offshore since 1978 and industry awareness of its superiority for use in marine environments is increasingly evident as more and more operators question the use of stainless steel from both safety and economic viewpoints.

Graph Although initially more expensive than stainless steel, the proven life expectancy of TUNGUM make the long-term operating costs far more attractive. For example, the price of instrumentation tubing for a standard rig using stainless steel compared with using TUNGUM alloy is approximately half. However, by using stainless steel you can expect 5-10 refits over the life of a rig and, just by taking the price of tubing into account, costs quickly escalate as demonstrated in the graph. Not to mention the costs involved in rig shut down and ‘old’ tube disposal.

Another cost benefit is that, as a copper-based alloy, TUNGUM is relatively easy to bend, resulting in vastly reduced installation times compared to stainless steel - up to 1/3 less is not uncommon. Bearing in mind that the average installation costs for stainless steel are in the region of £17 - £30,000, further savings will be significant.