Condition Assessment of Water Pipelines
Applying NDT techniques to allow analysis of current and future structural performance capability
Condition Assessment of Sewer Pipelines
Applying NDT techniques to identify corrosion patterns unique to sewer mains which allow analysis of current and future structural performance capability
Failure Investigations
Failure investigations allow pipeline failure mechanisms to be determined and used to predict the risk of future such failures on the pipeline
Trunk Mains Leakage
Outputs from our inspection services are used to highlight section of main at highest risk of leakage, hence allow economic targeted use of leak detection surveys
Pipe Bridge Inspection and Repair
AESL specialise in the maintenance of aged pipe bridges from initial inspection and assessment through to repair and maintenance
Pipeline Surveys
Deterioration level of pipelines are significantly influenced by pipe coating performance and the soil corrosivity. Above ground surveys may be carried out to provide data useful for pipeline condition prediction and the targeting of inspections.
Instrumentation & Monitoring Services
Monitoring techniques for pipeline movement and induced stresses
Development
AESL carry out continuous in-house research and development as well as R&D projects for water industry customers


Click here to contact the Water Engineering Director for more information...


Click here to contact the Water Engineering Director for more information...

Condition Assessment of Water Pipelines

A major area of AESL's activities across the UK and internationally is the condition assessment of operational pipelines. AESL have developed processes for predicting the current and future leakage and structural performance capability of in-service water and sewage pipelines. The processes involve detailed pipeline inspection at selected locations, and statistical and structural analysis.

Pipeline inspection is carried out at locations where the pipe wall condition is considered likely to be representative of that of longer sections of the pipeline. At each selected location the pipeline is inspected externally over a 1m length and its full circumference. Details of the condition of the pipe coating, pipe environment and both faces of the pipe wall are recorded. An overview of the AESL pipeline inspection equipment and analysis methods can be found here.

The inspection data is analysed to provide estimates of current and future patterns of leakage and structural failures, under the applied pressure and external loading.

Major pipeline assessment activities are on steel and iron pipe, but project activities are also undertaken on PE, PVC, GRP and asbestos cement pipelines.

The assessment process allows comparison of the leakage and structural performance capabilities of sections of individual pipelines to assist in targeting maintenance or replacement activities.



Click here to contact the Water Engineering Director for more information...

Condition Assessment of Sewer Pipelines

A major area of AESL's activities across the UK and internationally is the condition assessment of operational pipelines. AESL have developed processes for predicting the current and future leakage and structural performance capability of in-service water and sewage pipelines. The processes involve detailed pipeline inspection at selected locations, and statistical and structural analysis.

Pipeline inspection is carried out at locations where the pipe wall condition is considered likely to be representative of that of longer sections of the pipeline. At each selected location the pipeline is inspected externally over a 1m length and its full circumference. Details of the condition of the pipe coating, pipe environment and both faces of the pipe wall are recorded. An overview of the AESL pipeline inspection equipment and analysis methods can be found here. Our Technology

Sewage and the gases produced by sewage can be aggressive to the pipe material, resulting in extensive internal deterioration and increased overall pipe wall deterioration rates. Gases such as hydrogen Sulphide (H2S) create a corrosive environment where distinct patterns of corrosion form on the internal surface of the pipe wall. Erosion due to scour has also been identified as a cause of pipe wall deterioration. AESL have developed expertise in identifying and quantifying these forms of pipe wall defect using imaging software to interpret inspection data.

These patterns of corrosion can, over a relatively short period of time, lead to a significant risk of pipe barrel fracture if loading regimes are sufficiently high, or leakage if loading is low.

Rising mains can suffer more regular high-pressure surge loading, due to trapped effluent gases resulting from gas production and cyclic pump operations. Air valves are fitted to rising mains to minimise the accumulation of gases and in some cases to allow air ingress. However, during AESL surveys of rising main air valves, many were found to be inoperative, and surge is considered in the AESL performance analysis. The evidence of rising main failures due to surge has led to AESL developing an Air Valve Monitoring System.

The inspection data is analysed to provide estimates of current and future patterns of leakage and structural failures, under the applied pressure and external loading.

Major pipeline assessment activities are on steel and iron pipe, but project activities are also undertaken on PE, PVC, GRP and asbestos cement pipelines.

The assessment process allows comparison of the leakage and structural performance capabilities of sections of individual pipelines to assist in targeting maintenance or replacement activities.

Case Studies:



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Failure Investigations

Investigations into pipeline failure events is a valuable tool, allowing pipeline failure mechanisms to be determined thus provide useful information on the potential for future events to occur.

AESL can provide an effective approach to diagnosing causes of failure in pipe systems, by assessing the failed samples geometry, level of deterioration, material parameters and construction / installation qualities, comparing these against probable failure mechanisms for the material.

If appropriate contemporary industry Standards and installation guidance document are consulted to ensure compliance with best practice at the time of installation.

Failure investigations can include recovery and examination of pipeline failures as well as on-site and laboratory testing.

Case Studies:



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Trunk Mains Leakage

The cost of leakage surveys on large diameter trunk mains is much higher than leakage surveys on small diameter distribution networks, largely due to high excavation costs to provide access. Trunk mains have few accessible locations allowing the use of leakage detection instruments, without excavation. In addition, the bigger the pipe diameter the shorter the distance leak noise travels along a pipeline. Thus, for effective leak detection on large diameter mains, it is likely to require that numbers of access points relatively close together. In order to allow effective, economic trunk mains leak detection AESL have developed their inspection and statistical prediction technologies to allow comparison of the likelihood of leakage along the route of trunk mains.

Trunk Mains Leakage Detection

Water industry pipeline networks have been constructed over a very long period and the majority of pipelines in them are deteriorating. External deterioration in ferrous pipelines is commonly a combination of general and pitting corrosion. However, the pipe material, corrosion protection provided, the corrosivity of the pipelines environment, and the pipelines age define the severity of the corrosion. These influences cause variations in pipe wall condition along individual pipelines, and across pipeline networks, resulting in significant variations in the likelihood of through wall leakage. These issues are considered to have resulted in a very limited application of externally applied leakage detection surveys to water trunk mains. The alternative approach of using internal leakage detection technologies is being undertaken, although also influenced by the need to access long trunk mains at sufficient locations to provide a full leakage survey.

Predicting Trunk Mains Leakage

Recognising these issues AESL have developed a method for predicting sections of trunk mains where pipe barrel leakage is most likely, using the results of the Company’s selective external pipe wall inspection technologies.

Pipe barrel leakage results when external or internal pitting corrosion defects develop to be through wall. Pitting corrosion defects are considered to be hemi-spherical in shape. Therefore, a defect registering as being through wall using NDT may not be leaking due to it having only a small area of very thin wall, withstanding the water pressure aided by the soil pressures. For leakage to occur, the defect needs to grow diametrically sufficiently for the water pressure to displace the corrosion products and supporting soil. Thus, the likelihood of leakage depends on the area of pipe wall defect area, and the water pressure.

The AESL analysis of pipeline performance involves treating the pipeline in sections defined by similarities in local corrosion patterns. The results from inspection activities carried out in each section are then used to statistically predict the condition of longer sections of pipeline. Based on this pipeline sectioning process, AESL can use the local pressure profile and statistical predictions of the area of pitting defects in each section to compare the likelihood of leakage.



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Pipe Bridge Inspection and Repair

Inspection:

Where pipelines are supported on pipe bridges, the integrity of both the pipeline and support structure are critical to the pipelines continued operation. However, age and location can result in both undergoing significant deterioration.

Pipe bridge design and construction details vary greatly and can include the use of grey, wrought or ductile iron, or steel components. AESL can undertake the inspection and assessment of pipelines and pipe bridge structures and, where appropriate, undertake remediation activities.

Structural Analysis of bridge:

Pipe Bridge Inspection and Repair

Structural analysis software is used to check stresses and deflections of the deteriorated structure are within allowable limits.

Pipeline Coating

The Company offers complete re-coating and refurbishment services for above ground pipelines and associated integral structures, principally bridge crossings.

The process can include grit blasting, pipe wrapping and painting using two pack epoxy and polyurethane coating systems. The Company applies tape and liquid coating supplied by Winn & Coales who have been providing anti-corrosion coating and wrappings for over 100 years. Winn & Coales issued AESL with its first approved applicator certificate based on the quality of the work carried out.

Case Studies:



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Pipeline Surveys

When considering structural deterioration of buried sections of pipelines, the deterioration level is significantly influenced by pipe coating performance and the soil corrosivity. Above ground surveys may be carried out to provide data useful for pipeline condition prediction and the targeting of inspections:

  • Soils surveys to assess variations in the corrosive properties of the soil to the pipe material
  • Pipe coating surveys using a Pipe Current Mapper (PCM) allows assessment of variations in the pipe coating

Geographical Information System (GIS) Data Collection Surveys

The water industry operators rely on an accurate understanding of their systems and assets. AESL offers a full survey service, from desktop study to hands on site surveying. Our staff are highly experienced water engineers.

Assets surveyed by AESL include:

  • Raw water aqueducts
  • Trunk mains and trunk main assets
  • Distribution mains
  • Service reservoirs
  • Scours
  • Pumping stations
  • Water treatment works
  • Water towers

Pipelines and pipeline assets may be identified and their location recorded by GPS up to sub metre accuracy where required, for GIS update. Asset condition and confirmation of operation may also be assessed during the survey.

Benefits include:

  • Greater understanding of Water Network
  • GIS/Corporate systems reflect actual site conditions
  • Optimisation of water sources to minimise operation costs
  • Asset condition may be assessed during survey


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Instrumentation & Monitoring Services

AES can install bespoke designed instrumentation and monitoring equipment for use on pipelines, during critical operations.

Since many pipelines have been in service for perhaps more than 50 years pipe or components can deteriorate to a level where they no longer function as they should, and many eventually become liable to fail. The installation and monitoring systems to collect data confirming pipeline performance can allow the user to better manage operational procedures and put the necessary controls in place to mitigate any problems.

Service provided includes:

  • Specification of the data logger and instruments
  • Installation of the monitoring systems including:
    • Vibrating wire strain gauges
    • Linear displacement transducers
    • Acoustic monitoring devices
  • Auto logging of the data
  • Data analysis and interpretation

Case Studies:



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Development

MFL - Triaxial Sensors

AESL have successfully operated their high flux magnetic inspection tools on ferrous pipelines for around 18 years. This technology has a major advantage over other inspection techniques in its capability to identify and size pitting corrosion defects. Pitting corrosion defects, if sufficiently large and under sufficiently high stresses, can initiate structural fractures. Pitting corrosion can also lead to through wall leakage.

The AESL magnetic inspection tools have had on-going technical development, related generally to inspection data recording and communication. Current development focuses on the magnetic leakage sensor array, with the additional of two sets of sensors, aligned to investigate different defect characteristics. These ‘Tri-directional sensors’ improve inspection performance, but particularly enhance the inspection of thick wall grey iron pipe, and the predicting of trunk mains leakage.

The AESL magnetic inspection tools induce magnetic flux into the pipe wall and use on-board sensors to measure flux displaced from the pipe wall, at locations where there are non-metallic pipe wall defects. The shape of the displaced magnetic flux is related to the defects size and shape, although the original AESL magnetic inspection tools carry sensors that optimise determining defect depth, with the defects shape being considered hemispherical during further analysis. The two additional sets of inspection sensors, orientated to determine the defects length and width.

The tri-directional sensors can improve automated identification of pipe wall defects because each sensor orientation provides a different, but repeatable metal loss signal shape. Using the three signal shapes to confirm a defect response can increase the confidence that all defects are identified. Grey iron has a non-homogenous structure, and generally has many non-metallic inclusions, which appear as background noise signals in the magnetic inspection results. The level of this background noise and the ability to identify defect signals within it defines the minimum identifiable size. Thus, the improvement to the defect identification and sizing can provide improved inspection performance generally, and particularly on thick wall pipes where achievable flux density levels are lower.

In assessing pipelines, AESL can use the pipe wall inspection results to statistically model the pitting corrosion patterns in uninspected pipeline sections. This statistical analysis currently considers the likely pitting corrosion depths, up to potentially through wall defects that may be leaking. Improving the prediction of the likelihood of leakage requires that the surface area, and depth of defects be determined, using the results from the Tri-directional sensors inspection tools.



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smartCat

Magnetic Flux Leakage Tool

The smartCat patented, inspection equipment allows the rapid non-intrusive assessment of the condition of metallic pipes.

Using magnetic flux leakage (MFL) technology along with proximity, distance and azimuth sensors both internal and external defects are identified and measured and their location recorded.

Pipelines of 300mm diameter and upwards can be inspected using a multiple pass of the smartCat. The process involves scanning the pipe along its length in 'slices' with the tool being indexed around the circumference after each scan.

The smartCat indexed feature allows the full circumference to be scanned with the angular position being recorded for each 'slice' from the azimuth. The software utilises the azimuth data to re-construct full circumference as one 'picture'.

Standard pipelines diameters of 75mm, 100mm, and 150mm can be inspected in a single pass using the smartCat 360. Other sizes can be manufactured to order. The smartCat 360 wrap around feature allows the full circumference to be scanned simultaneously.

The data is sent via bluetooth technology to a hand held PDA for onward transmission to the AESL servers from anywhere in the world

Operation of the smartCat is carried out on-site by a two man team.

Using software the data is downloaded from the smartCat to the AESL servers for a 'initial analysis' to allow any identified major defects or anomalies to be considered before the technicians leave site.

The client can then be informed of any potential immediate problems so that corrective action can be taken.

MFL testing is routinely used by AESL in the following processes:



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Ultrasonic Inspection

Advanced Engineering Solutions offers conventional NDT services for the inspection of wall thickness. AESL have technician staff who are externally qualified to apply these inspection techniques to Ultrasonic PCN Level 2 Sector W.

For a standard pipe condition assessment the pipe is inspected over the full circumference and a short sample length, where access allows:

  • Inspecting the full circumference of the pipe ensures that variations in corrosion patterns around the circumference are identified
  • Our defined pattern of ultrasonic spot readings allows variations in wall thickness around the circumference due to manufacturing defects or large corrosion defects to be identified

The results of the ultrasonic inspection in conjunction with and magnetic flux leakage inspection may be used to confirm the integrity of the pipe wall.

If specific corrosion patterns are suspected in the pipe wall targeted inspection may be carried out using the B Scan ultrasonic mode. This has the ability to sweep a small area and thus pick up larger areas of wall thickness variation in pipes or vessels.



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Pipe Penetrating Radar

Utilising commercial radar technology the integrity of concrete / cement pipes and structures may be investigated.

Radar Inspection

Applications of this technology include:

  • Condition Assessment of Asbestos Cement pipe
  • Inspection of concrete structures


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Flaw Detection

Advanced Engineering Solutions offers conventional NDT services for the inspection of wall thickness and cracks in welds for pipes and vessels.

AESL operates Standard Ultrasonic Inspection, B Scan ultrasonic inspection and Magnetic Particle Inspection, and Dye Penetrant inspection.

AESL have technician staff, who are externally qualified, to apply these inspection techniques as follows:

  • Ultrasonic PCN Level 2 Sector W
  • Magnetic Particle Testing
  • VS02 Inspector
  • Dye Penetrant Inspection


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Acoustic Air Valve Monitoring

AESL have recognised during sewer and water pipeline failure investigations that failures are occurring at locations where the combined pressure and external loading is much lower than that calculated to cause failure. Such failures are also seen to be occurring close to air valve positions, and during air valve surveys many inoperative air valves have been identified. Air valves are fitted to pumped and gravity fed sewers and water mains to release air or gas and, in some cases, allow air ingress to the pipeline. Pockets of trapped air or gas in a pipeline can significantly increase surge pressure peaks, and air ingress can be required to prevent vacuum pressures developing. Importantly, pipeline restrictions caused by air or gas pockets can significantly increase pumping costs and reduce flow capacity. Thus air valves play an important part of maintaining pipeline integrity, and in the cost of their operation. Recognising the importance of ensuring that air valves are operating correctly, AESL has developed an ‘Air Valve Monitor’.

The Air Valve Monitoring

It is currently difficult to confirm that an air valve is operating because they are very often difficult and expensive to access being in chambers in roads or on private land, and on pipe bridges etc. In addition, they operate automatically and at random times, so a partial on-site strip down is generally required to confirm their operation. The air valve monitor is designed to be positioned on the air valve body and to record the times at which it operates and the noise signals generated during its operation.

Acoustic Air Valve Monitoring

The monitor is attached to the air valve body using magnets, or cable clips where necessary, is battery-powered and is contained in an enclosed box, which is intrinsically safe to the appropriate level for operation in sewer chambers. The monitor could initially be installed to confirm whether or not an air valve is working, and can be left in place to record patterns of operation, any change in performance through to providing warning of non-operation.

Computer-based signal analysis is also available to allow rapid comparison of the valve monitoring signals patterns, and potentially identification of any valve performance changes.

Acoustic Air Valve Monitoring Wave

The repeated patterns of air or gas release provide the opportunity to compare the operating patterns of all valves on a pipeline and hence determine which are most critical to pipeline performance. The influence of pumping regimes on air or gas release may also be investigated using these recorded signals.



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Instrumentation & Monitoring Services

AES can install bespoke designed instrumentation and monitoring equipment for use on pipelines, during critical operations.

Since many pipelines have been in service for perhaps more than 50 years pipe or components can deteriorate to a level where they no longer function as they should, and many eventually become liable to fail. The installation and monitoring systems to collect data confirming pipeline performance can allow the user to better manage operational procedures and put the necessary controls in place to mitigate any problems.

Service provided includes:

  • Specification of the data logger and instruments
  • Installation of the monitoring systems including:
    • Vibrating wire strain gauges
    • Linear displacement transducers
    • Acoustic monitoring devices
  • Auto logging of the data
  • Data analysis and interpretation

Case Studies:



Click here to contact the Water Engineering Director for more information...

Urchin

Leakage from water pipelines is an increasingly high profile issue and sizeable volumes of water can be lost. These non-revenue water leaks need to be reduced.

The location of leaks can be difficult to determine in pipelines especially over long distances.

The Urchin is an in pipe leak detection system for water pipelines.

  • Urchin is an autonomous free floating remote device that can detect leaks from within water pipelines
  • Urchin can be operated on live pipelines with minimal disturbance and no interruption to supply
  • The device may be launched and retrieved through existing or bespoke fittings where required
  • Urchin is compact; contained within a maximum diameter of 75mm and can be operated in metallic and plastic pipelines
  • In excess of 15Km of pipeline can be inspected per operation
  • Valves and bends in the pipeline can easily be negotiated by the device
  • The route of the Urchin is monitored at regular intervals.
  • It is equipped with a position locating system so that its progress can be monitored as it travels inside a pipeline
Urchin
Urchin

Using the data from the position locating system AESL can accurately determine the location leaks along a pipeline, thereby facilitating subsequent repairs and improving the operational efficiency of the water network.

Current development activities focus on launch and retrieval systems via common valve configurations.



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