Centrale idraulica per ambienti artici.

Specialised in the Management of Process Valves

A well-established reality in the Oil & Gas sector, Duplomatic MS is a reliable partner in plenty of applications ranging from “full stainless steel” cabin HPUs for hostile environments, to valve blocks with special treatments for “off shore” and “subsea” applications, up to hydraulic cylinders customised according to end users’ specifications.

Despite being at the head of a rapidly expanding group, Duplomatic MS has maintained the flexibility of a company able to follow step by step the requests of the sector, designing and manufacturing special components to optimize the performance and reliability of the systems produced. Specifically, Duplomatic’s Hydraulic Systems Business Unit is specialized in the design and construction of custom projects for different application sectors: from industry to energy, from the steel industry to off-shore and Oil & Gas applications.

Encased hydraulic power units for the arctic zone

In the field of process valves positioned along the outdoor pipes of a methane pipeline, Duplomatic MS has realised a series of “stand alone” encased hydraulic power units installed in the Arctic area. All the hydraulic components are made of Aisi 316 steel, as well as the protection casing. The electrical parts (solenoid valves, instrumentation and junction box) are in accordance with ATEX standards because they operate in a classified area, being installed outdoors, but close to the pipeline. The extreme climatic conditions, with temperatures of -40°C, required a redesign of the main “fail safe” components. The fail-safe condition is managed by monostable solenoid valves in series which act on the piloting of logic elements. The fail safe flow rate is provided by a bladder-type accumulator. These process valves remain open for long periods and must close within a short time if necessary. It is therefore necessary to ensure a high level of reliability of all components making up the emergency closing chain. A fluid with a high viscosity index, particularly suitable for temperatures down to -54°C, and seals fit for the climatic conditions were used. The unmanned process valves are operated by quarter-turn actuators and operate in on-off mode.

Control units for oil pipelines withstand high temperatures

Also in the field of process valves, control units have been built to operate valves used for sectioning large oil pipelines. The environmental conditions include high temperatures (above 50°C) and protection of the plant from possible sandstorms. The entire unit is encased, with high performance sand filters applied to the walls; the internal ventilation is not high, and this is one of the reasons for opting for a hydropneumatic pump. Even in this case it is a question of operating in a classified area. In order to avoid the use of electrical parts, pneumatically controlled components made entirely of Aisi 316 steel were used. Again, the process valves are operated by quarter turn on-off actuators with fail safe supply ensured by a dedicated accumulator unit.

Flow control units for desert installations

Not just on-off controls. For a plant installed in a desert area, a series of flow control units on regulating ball valves have been designed and manufactured. The hydraulic part is housed in an Aisi 316 cabinet which also contains the cycle management PLC. The particularity of this application lies in the position control of very small actuators (therefore reduced volumes), with a positioning accuracy of 5% of full scale. In some cases the flow rate to be controlled is < 0.05 l/min. Proportional control due to continuous regulation would have generated a sudden rise in the temperature of the fluid in the tank, also in view of the poor heat exchange with an environment that is normally at 40°C and the poor internal ventilation due to the casing.
A special circuit has been designed with sealed Aisi 316 solenoid valves and step positioning. The speed control is entrusted to the compensated flow regulators realized by Duplomatic with body in Aisi 316 steel.

Off-shore and subsea applications join those on-shore

Duplomatic MS is historically a manufacturer of hydraulic components: thanks to the company know-how and to a structure specifically dedicated to the testing of prototypes, it has developed components not only in stainless steel with Atex certification for the on-shore Oil & Gas industry, but also for off-shore and subsea applications. Recently, manifolds complete with solenoid valves in custom execution suitable for working at depths of more than 2,000 m below sea level with control fluid operating pressures of 210 bar have been produced. This is a servo-assistance for equipment
which carries out maintenance on subsea pipelines. The main problems encountered during testing are related to the high environmental test pressure which the components must withstand in order to meet specifications. The protective casing alone cannot withstand the underwater pressure, so it is necessary to ensure that a pressure equivalent to the external pressure is generated inside the casing. The test condition requires a pressure of 300 bar outside the manifold. Normally solenoid valves are designed to withstand high pressure on the internal lines. In this case, the test pressure on the outside of the body and coils is higher than the working pressure of the hydraulic fluid. Still in the “subsea” sector, a 3-way, two-position mechanically-controlled valve capable of being installed at a depth of 1,000 m below sea level is currently being tested. The operating pressure of the valve is 200 bar. Even in this case, the entire valve is made entirely of Aisi 316 steel, except for the pin sliding bushing acting as hydraulic end-stroke on the clamps blocking submarine pipes for joint welding.

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