Increased working pressures, combined with longer project lifecycles and the ever-present threat of corrosion, mean that instrumentation tube connections are being subjected to tough environments. To help ensure connection reliability, many instrumentation engineers utilise ‘cone and thread’ connections when working pressures in excess of around 6000 psi.
Pioneered by Parker Autoclave Engineers (Parker), these ‘cone and thread’ connections are renowned for their strength and ability to accommodate repeated assembly and disassembly. They are the industry’s preferred choice for medium pressure instrumentation (typically up to 20 000 psi) in offshore oil and gas applications worldwide. However, forming the cone and then cutting the thread requires skill and preparation time – each connection can take a trained installer 15 to 20 minutes.
A solution for instrumentation tubes
Consequently, there is a growing demand for a high integrity medium pressure instrumentation tube connection solution that is quick and simple to make and install. Parker has responded to this demand by developing a new generation of valves and fittings that are based on innovative ‘flared cone connection’, or FCC, technology. Combining the simplicity of compression style fittings with the strength of cone and thread, flared cone connections can typically be installed in less than four minutes – around five times faster than cone and thread.
Flared cone connection technology
FCC technology is based on a single sleeve compression style system, where, unlike conventional designs, the tube end is flared to prevent any possibility of ejection – and also provides the connection’s primary metal-to-metal seal. When the gland nut is tightened, the inside surface of the anti-ejection flare partners with a cone in the fitting or valve. The compression sleeve then partners with the body of the component to form a second, redundant, metal-to-metal seal. This dual seal approach has a major safety benefit; in the unlikely event that the primary seal fails, the secondary seal preserves connection integrity. Flared cone connections are also inherently resistant to vibration, making them especially cost-effective in applications where traditional connections would require additional anti-vibration glands.
FCC technology demands considerably less skill
Compared to cone and thread, flared cone connections are much simpler to make up and demand considerably less skill. A compact hydraulic set tool is first used to fit a compression sleeve which bites deeply into the tubing to create a mechanical support shoulder. This same tool is then used with a second die to form a flared end on the tube. The entire process is controlled by the set tool which helps to prevent assembly errors that could compromise connection integrity. Subsequently, installing the connection is simply a matter of screwing the gland nut into the fitting or valve and tightening it to the prescribed torque.
Adapted from press release by Cecilia Rehn