Ultramonit™ System Corrosion Monitoring From Sensorlink

Corrosion Monitoring Ultramonit™ System

Non-Destructive Testing (NDT) using ultrasonic technology

The Ultramonit™ system uses ultrasonic pulse-echo technology to provide accurate measurements of internal corrosion and erosion rates.

Ultrasonic pulse-echo measurement is a well-established NDT (non-destructive testing)[1] method for measuring wall thickness and detecting defects. When it comes to corrosion monitoring, ultrasound has distinct advantages compared to other available technologies. It is non-invasive and measures the metal thickness directly and not via more or less dependable indicators.

Advances in low-noise electronics, sensor technology and signal processing algorithms now make it possible to achieve high resolution results using a permanently installed ultrasound unit.

[1]NDT – Non Destructive Testing

The use of noninvasive techniques to determine the integrity of a material, component or structure or to quantitatively measure a characteristic of an object, i.e. inspect or measure without doing harm. Source: http://www.ndt-ed.org/index_flash.htm

Key advantages:

• Non-intrusive, meaning no threat to the integrity of the pipeline
• Number and placement of sensors determined according to client needs
• Predicts wall thickness reduction rate with very high accuracy
• Provides data to enable the prediction of the remaining lifetime of the pipeline
• Provides feedback on the effectiveness of corrosion inhibitors
• Efficient installation without interfering with the pipeline operation
• The equipment can be moved between different pipeline locations
• Data can be collected on line and in real time
• Data communication either wireless or via cable
• Direct access to results provided from any PC
• Delivers real time data
• Automated measurement, logging and analysis
• Flexible measurement intervals determined by client
• Can be installed subsea
• Can be installed on new pipelines or retrofitted to existing lines

Subsea Installation

The Ultramonit™ equipment can be installed and operated without interfering with the operation of the pipeline. It can also be removed and reinstalled in another location if the client desires. In the case of subsea pipelines, the equipment is deployed through use of an instrumented clamp which can be installed on new or existing pipelines by diver or ROV.

Installation on existing pipeline infrastructure

In order to install the Ultramonit system on existing pipelines, it is necessary to excavate a small section of the pipeline in order to make it fully accessible. Concrete and thermal insulation coating must be removed but thinner corrosion protection coating like FBE (Fusion Bond Epoxy) can be left on the pipe.

Depth and temperature

Ultramonit is currently qualified for installation at a water depth of 1000 m but can be qualified for even greater depths on request. Standard operating temperatures range from 60 to 90 degrees C (140 to 194 F) but these limits can be changed if and when required.

Configuration and Application

Ultrasound transducers

The number and placement of transducers within the Ultramonit™ clamp are typically determined and agreed with the client. The selection will usually be based on known or suspected areas of corrosion within the pipeline in question.

The width of an Ultramonit clamp typically vary from 0.5 metres to 1.5 metres. Tranducers can be positioned around the entire circumference of the pipe and also set to stretch out in the longitudinal direction.

Pre-set criteria and time intervals

The Ultramonit system can provide data in a form suitable for the end user.

For example, the client’s allowable limit regarding corrosion in the pipeline can be entered into the Ultramonit system. The pipeline’s average wall loss is then measured against this limit in order to provide the operator with a clear picture of what is going on inside the pipeline.

The system is capable of providing periodic measurements of the level of corrosion at intervals set by the operator.

The prediction module within the Ultramonit data processing system provides an estimate of the corrosion rate. Thus, it is possible to predict the future corrosion and loss of wall thickness along with pipeline remaining lifetime projections.

Pipeline size

The Ultramonit system is available in all pipeline sizes and is designed to fit each individual pipeline.

Applications

The Ultramonit system can be used on any pipeline in which loss of wall thickness needs to be monitored, be it subsea, topside, onshore, in processing plants or in refineries.

The system is useful when performing the following tasks:

• Optimizing the use of corrosion inhibitors
• Predicting the remaining lifetime of an asset on the basis of corrosion rate
• Performing verification and calibration of inspection pig data by directly monitoring critical areas
• Monitoring corrosion and erosion of flowlines and pipelines

A proven record of performance

The versatility of the system is demonstrated by the range of projects in which it has already been employed, including a gas treatment plant, a 34-inch oil export pipeline and a 14-inch water injection riser.

Wall Thickness

Ultrasonic measurement of wall thickness has conventionally been carried out manually by use of a suitable ultrasonic transducer and a measuring instrument—in most cases a basic probe utilizing a simple contact transducer to determine the thickness of the pipeline wall at a specific spot. This method usually yields a typical accuracy in the range of plus or minus 0.1 to 0.2 mm, depending on the skill of the operator.

The Ultramonit™ technology is capable of measuring changes in the wall thickness with greater accuracy, thus avoiding the uncertainty caused by inadequate instruments or unskilled operators. Wall thickness can be measured to a very high accuracy by repeating measurements at the same spot over time with permanently installed instrumentation.

Resolution of such high quality and accuracy has been made possible by careful refinement of our equipment, production and technology, with notable innovations in the following areas:

• Signal processing
• Electronics with high signal to noise ratios
• Optimum placement of transducers relative to the pipewall
• Electronics and transducers capable of operating in seawater at great depth and in high temperature
• Temperature compensation capability: the system is able to adjust to variations in the speed of sound caused by temperature variations in the medium (seawater or steel)

Corrosion monitoring of existing subsea pipelines

The Ultramonit system is particularly valuable in offshore fields that have been in operation for a considerable time. Improved exploration and production methods have extended the viability of many fields, allowing operators to continue production longer than was originally anticipated. This has meant that pipeline systems have often exceeded their original design life of 20 to 25 years. The older the system, the more important control and knowledge of internal pipeline corrosion and integrity management become. The Ultramonit system allows operators to continue using older systems in confidence, safe in the knowledge that problems can be detected before they become critical.

Data Presentation

All functions required to operate the transducers, including data processing, are actioned through SAM (Sensor Array Module) electronic cards. The ultrasonic transducers and their associated electronics are installed in polymer cassettes. A number of these cassettes are installed in the Ultramonit™ monitoring clamp which is connected to a data logger.

The data-logger provides a real time two-way communication link with the outside world via cable or acoustics. It can, alternatively, store the data locally for subsequent collection.

Graphical data presentation

Measurements collected from the data-logger are stored on a dataserver. Monitoring data are made available to the end user via a WEB based graphical user interface. This interface allows for quick evaluation of corrosion status by traffic light colour logic.

The end user can study the raw data from each transducer, or apply filters to enable a quick view of any transducer that has detected a corrosion or erosion rate greater than a predefined value set by the user.

Inside Out With Ultramonit™ System