Abstract

We produce good quality, high strength, and sour resistant steel, but industry confidence in offshore welds to 65 Ksi and conservative codes lead to very thick pipes for all HPHT risers (SCR, Dry tree, drilling) and flowlines. Cumulative adverse effects of very thick and low D/t ratio pipes on pipe manufacturing, welding, inspection, and installation mean an alternative pragmatic enabler is essential. When compared with active HIPPS (High Integrity Pressure Protection System), a passive full pressure capable system was found with better life cycle cost, greater confidence, and higher risk assurance. A full pressure system, using mechanical connector, is an enabler for HPHT risers and flowlines.

Different types of mechanical connectors, using high strength pipes, have been examined through the whole spectrum of materials selection, quality manufacture, application and installation, reliability, and pipe joint repair/replacement in deep water. Relative costs amongst alternatives, technology status, qualifications required, and risk management issues have been assessed.

Mechanical connectors were found suitable for joining high strength pipes. There are different types of connectors to choose from depending on the types of risers and flowlines and attending pressure, temperature, and application. Grayloc connector demonstrated some limited use, especially as an enabler for easy repair replacement of high temperature flowlines. It has the potential to be a strong contender if some efforts in new design and qualification tests are provided.

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