PROTEC was asked by a major oilfield service and supply company to design, manufacture and test a production HPU for deep offshore West Africa in accordance with the customer’s basic parameters. The overall philosophy was to maximize availability of the system and to minimize intervention for maintenance. The HPU is part of the topside control system and its purpose is to supply clean hydraulic fluid with sufficient pressures and flow to operate the valve actuators on the subsea trees and manifolds.
The HPU had to meet IEC 60079 Class 1, Zone 2 hazardous area classification requirements. The HPU is water/glycol based and meets NAS 1638 Class 6/SAE AS4059C Class 6 (B-F)cleanliness levels. All metallic material in contact with the hydraulic fluid is 316, 316L stainless steel. The hydraulic fluid reservoir is 316 stainless steel (400 Gal Supply, 300 Gal Return). The structural frame is carbon steel with offshore marine coating (zinc polyurethane epoxy 3-part coat system) and the frame and lifting pad eyes are built in accordance with DNV 2.7-1. There is a 5,400 psig low pressure circuit with four 15-gallon bladder type accumulators and two 20 HP motor driven 5.2 GPM piston pumps. There is a 10,000 psig high pressure circuit with two 7.5-gallon piston type accumulators and two 20 HP motor driven 1.3 GPM piston pumps. A local mechanical control panel is provided on the skid with all local monitor and control equipment (pressure gauges, valves, hydraulic regulators, etc.). The electrical panel is rated IEC 60079 Class 1, Zone 2 and is fully outfitted for control and monitoring purposes with supporting equipment for power and communication with the master control station.
For this same project PROTEC also manufactured the TUTA and a test and flushing HPU.