Hughes delivers deepsea pressure testing system to Subsea 7

Equipment & Technology - September 19, 2012

Specialist manufacturer Hughes Pumps recently supplied a number of high precision flexible line Hydrostatic Test and Chemicals Injection System (HTCIS) units to Subsea 7.

The HTCIS units will be used on Subsea 7’s Lochnagar, Kommander 3000 and Normand 7 pipelay support vessels (PLSV) operating throughout Brazilian and South American waters, enabling the integrity of flexible flow-lines laid to the seabed in up to 2,000m of water to be pressure tested before oil is pumped through them.

The HTCIS unit consists of four different and integrated modules connected to a single supply line, including the filling system (FS) comprising a fixed speed centrifugal pump to rapidly prefill flowlines with seawater at 50 m³/hr at 10 bar, a 1,000 litre 316 stainless steel, seawater supply tank for the mid and high pressure pumps.

A mid pressure system (MPS) using a Hughes triplex plunger pump to provide flow from 0 to 10 m³/hr at up to 207 bar, A high pressure system (HPS) uses a Hughes triplex plunger pump to provide flow to 0.4 m³/hr at up to 517 bar.

The chemical injection system (CIS) simultaneously injects oxygen remover and biologic inhibitor into the high pressure discharge line, at controlled rates based on flow meter readings fitted to the variable speed MPS and HPS pumps to maintain the required chemical concentrations.

The CIS uses an automatic 'closed loop' system to automatically maintain flow rates, discharge pressures and chemical dosing rates, however other versions using manual control are also available.