New tungsten carbide process could improve offshore valves

Total Carbide claims its Intraform technology will give engineers better flexibility when designing flow-control components and reduce the impact and cost of downtime through component failure or unexpected maintenance requirements.

Tungsten carbide — a compound containing tungsten and carbon atoms — is stiffer and harder than steel, and has an extremely high melting point.

These hard-wearing characteristics mean the material has started to find a use in harsh environments, where abrasive or corrosive fluids are handled, such as the oil industry.

However, there are still difficulties when it comes to using tungsten carbide in complex components, as Andy Hunt of Total Carbide explained to The Engineer.

‘Before [Intraform], components were either made out of steel which obviously hasn’t got the wear characteristics, or it would had to have been two pieces of tungsten carbide.

‘The problem with that is, if you’re pressurising an internal form the fluids always find the weakest spot, which is the joint.’

Total Carbide’s Intraform technique starts with the raw material form of tungsten carbide – a fine grey powder which is then milled, pressed and sintered. Notably, the use of a computer numerical control (CNC) 5-axial machine allows the creation of one-piece components, such as valves with internal chambers, according to requirements.

‘Because we have sophisticated CNC equipment for the pre-sintered condition — in other words when it’s soft before it’s fired — we can put different internal forms in [such as] swirl patterns, which can be reasonably complex,’ Hunt said.

The process has been independently tested to industry standards, including a 25,000 cycle qualification test at 760 bar. Products have also been proof tested at 1,140 bar as part of FAT (Factory Accreditation Testing) without showing signs of failure, and have successfully undergone a 90-day corrosion test.

Hunt said Total Carbide will apply its technology to a number of different liner and rotary valves for the offshore oil industry, as well as potentially other industries.

‘We look at the drawings and concepts of what [clients] are trying to do and engineer their product to incorporate tungsten carbide components right from the start.’

Commenting on the impact of the technology for the wider industry he said: ‘I think it may expand the use of tungsten carbide into many other areas that probably don’t have tungsten carbide already.’