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Sensing and success in Oil and Gas

There is a broad range of sensors required on an oil rig, LNG terminal, and other critical settings involved in the resources industries sector. Below are a few types of sensors, and some reasons why expert advice is essential.

Monitoring, maintenance and meeting strict standards are all important parts of operating in Oil and Gas. Possessing all the sensing equipment to keep tabs on an LNG plant,

gas wellhead or other critical sites requires a variety of different sensors and the expertise to integrate these.

Here are some of the commonly used types of sensors in the Oil and Gas industry and some of the biggest challenges chemical processors face when it comes to using LVDTs, pressure and temperature sensors.

Pressure sensors deployed in drilling and exploration and other Oil and Gas environments need to be high performance with high reliability and accuracy. Liquid / gas compatibility and potential contamination are challenges associated with sensor use. Certain sensor technologies are limited in the material that can be used or the method in which it is sealed. As an example, ceramic pressure sensors are clamped to a metal process connection with an O-ring seal. While ceramic has good compatibility with various liquids and gases, O-rings need to be selected carefully and considered in the compatibility process. O-rings can also have a limitation in temperature. Pressure sensors using thin-film and bonded foil strain gage technology also have limitations in the base material of the sensing element. The oil/gas process industry uses NACE MR0175 as an industry standard for material. Bestech offers appropriate material as a standard sensor material to suit various applications.

The 21D/DC RFID series from Bestech, on the other hand, are unique solutions combining industrial pressure sensing with RFID wireless communication and data logging. The pressure transponders combine extremely sturdy, tried-and-tested industrial pressure transmitters and advanced RFID (radio frequency identification) wireless technology.

The D line OEM piezoresistive transmitters used to measure pressure are based on patent chip-in-oil technology. They come in robust, laser-welded, hermetically sealed

stainless steel housing, which is filled with oil for pressure transmission, contains the pressure transducer and the ultra-energy-efficient compensation electronics with I2C interface.

Also available are IECEx certified (meeting Australian & New Zealand standards for working in explosive environments) pressure transducers, transmitters and digital gauges.

Intrinsically safe pressure and submersible level sensors from Bestech Australia are manufactured to meet requirements for Class I Division 1 Zone 0 hazardous locations.

Linear variable differential transformer (LVDT) sensors have a very stable output signal due to their differential transformer design. They are designed for a wide range of industrial and scientific position feedback or measurement applications.

LVDT sensors have very high repeatability and show the exact same measurement on restarting after power outage with no positional information being lost. Apart from the uni-axial linear motion of the magnetic core, any other movements such as the rotation of the core around the axis will not affect its measurements as the moving core does not necessarily contact the inside of the stainless steel housing tube and it moves with almost no friction, thus, making the LVDT a highly reliable target contact-type sensor.

Introduction

Measurement, monitoring and leak detection

“Monitoring, maintenance and meeting strict standards are all important parts of operating in Oil and Gas”

Knowing what sensor technology goes with what application is no easy task and Bestech Application Engineers can provide expert advice in finding the optimal sensor for your application.

Bestech delivers state of the art industrial sensors, instrumentation and teaching equipment to numerous industries. It is a reliable and trusted supplier to industries including the manufacturing, military, mining, steel, rail, construction, automotive, chemical, pharmaceutical, food, water, Oil & Gas industries.

A leading provider for nearly two decades, Bestech offers free, expert consultation to help design custom systems.

Drawing on its experience, Bestech can help identify project requirements and potential pitfalls and offer the right solutions. All this comes with competitive prices, a range of the highest-performing products, and high-grade after-sales service.

To find out more about what’s available to help your Oil and Gas site run more effectively and safely, contact Bestech on 03 9540 5100 or visit http://www.bestech.com.au/

Putting it all together

Subsea applications pose special challenges for reliable LVDT operation, due to the presence of chemically hostile seawater that attacks common metals. Linear position sensors can become quickly corroded and pitted. Temperature, salt level and micro-organisms in seawater also can accelerate corrosion rates, leading to premature sensor failure.

To survive subsea environments, LVDT Linear Position Sensors must be housed in special alloys that support long-term operation in different elements. As a housing and core made from stainless steel will not survive well in many underwater applications, the LVDT casing must be composed of an alloy that provides chemical resistance to seawater and other corrosive acids to provide long-term reliable operations for many years. Reliability is critically important due to the cost of replacing sub sea hardware.

Depending upon the temperature, salinity, oxygen levels and depths of applications, the LVDT, with its hermetic seal and non-contacting operation, is often the only technology that can deliver accurate and reliable performance in subsea conditions. As Subsea LVDTs provide the same reliable performance as standard units but with more chemical resistance to seawater, they are replacing less

reliable linear position technologies such as pots and magnetorestrictive sensors for position measurement in underwater applications.

Spring-loaded LVDTs measure stationary LNG tank movement caused by earthquakes, floods and hurricanes, as well as vibration of subsea/underwater tanks.

TIM Infrared temperature sensor and real-time monitoring cameras are frequently used for leak detection and cool-down monitoring at LNG plants. They provide continuous, non-contact temperature monitoring, wide measuring range (from –50 degree Celsius and up to 1,800 degrees Celsius.)

Based on infrared imaging technology, these sensors provide visual thermograms that are images of radiation in infrared range of 9-14µm, detecting anomalies during pipeline operation.

The thermal imaging camera detects heat patterns, temperature values, and is based in a heat-resistant, rugged, and waterproof housing, rendering infrared radiation – such as that given off by warm objects or flames – into a visible light representation in real time.

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