SUBSEA SOLUTIONS FROM ESI

ESI Technology was established in 1985 and specialises in the design and manufacture of high quality pressure transducers and transmitters incorporating our superior Silicon-on-Sapphire sensor technology (SOS).

Oil, gas & subsea applications have become a speciality of the company. The ability of ESI to meet specialist requirements for the subsea market can be illustrated by the evolution of PR3913 control valve pressure transmitter.

PRESSURE TRANSMITTER’S FOR SEVERAL APPLICATIONS

ESI was approached by a manufacturer of Subsea Control Modules (SCM) with a very demanding specification. Pressure transmitters are required to be installed into SCM?s which are devices that are used to monitor and control valve functions on the sea-bed (valve position and flow). The SCM communicates with the surface by means of electro-hydraulic controls via an umbilical cable and allows the oil production company to distribute oil through networks and where necessary add and mix additives on deep-sea wells

Our brief from the customer was to design and manufacture a pressure transmitter to the following specification

? Work at 3000m submersion
? Measure up to 1000 bar reliably for up to 20 years.
? Must be constructed in corrosion resistant materials such as Inconel 625 and Titanium to provide resistance during injection of chemicals.
? Have secondary containment to 1600bar to provide environmental protection should the sensor be over-pressured.
? Be certified for immersion to 3300m by means of Hyperbaric testing.
? Be subjected to Environmental Stress Screening (ESS) to ensure long term stability and extended service life.
? Provide compact housing with special process connections and water-tight electrical interface.

Working closely with the customers engineering team, ESI were able to create the perfect solution and the PR3913 range was developed meeting all of the specifications required. Extensive qualification reports were commissioned and ESI were able to produce a qualified prototype which was eagerly accepted by the customer

Following on from the huge success of this design, ESI were then approached by various customers to try to incorporate dual redundancy into the transmitter design. In effect the customer required two completely independent sensors and electronic circuits incorporating into the existing housing of the PR3913. From the customers perspective this would mean substantial cost reduction in materials used in the construction of the valves by making them more compact. As the market for security of performance and reliability grew it also offered the possibility of modifying existing systems by replacing a single output transmitter with a dual redundant unit. In effect an additional transmitter could be added without costly modification to the valve design.

Additionally the PR3920 subsea differential pressure version was developed based on the same principle offering high accuracy differential pressure measurement on chemical injection valves. Typically differential pressures of 50 bar can be monitored with accuracy of 0.25% of reading. The unique design using ESI?s Silicon-on-Sapphire sensing technology permits extremely high line pressures of up to 1000 bar to be applied independently to either of the two pressure ports without affecting the performance of the transmitter.

It is not difficult to understand why ESI is so successful in this field. At the heart of the design is ESI?s unique Silicon-on-Sapphire sensor technology; a sensor not only with high sensitivity and stability but also rugged and resilient against high overload pressures and transients. Using this unique sensor a range of subsea transmitters was created and by communicating and listening carefully to customer requirements the technology was integrated into housings suitable for extreme conditions.

Pre-conditioning and testing is fundamental to the success of this range. ESI?s investment in hyperbaric test facilities means that units supplied have already been subjected to 3300 metres of submersion before leaving the factory and the customer can rest assured that there is no concern about leakage or integrity when deploying instruments in deep sea wells.

Investment in vibration test equipment and automated thermal chambers means that transmitters can be environmentally screened at ESI before shipment confirming that the units are fit for more than 20 years of reliable service on the seabed. This is a major benefit to the customer as the cost of valve retrieval from subsea is extreme

This investment and commitment means that every customer receives a complete package of documentation with each transmitter confirming calibration, accuracy, material conformity, hyperbaric test and ESS test certificates

Document packages have become a standard requirement in this market and ESI will be ready to support any new requirements that arise. We will continue to listen to customers and research and develop new solutions.