Pipelines are widely accepted as being the safest and most economical means of transporting hydrocarbons over long distances. However, as they age, they can corrode, fatigue, or become damaged in service, leading to product leakage. Consequently, leak detection methods are important to pipeline operators.
Most operators use sophisticated online detection systems, but these systems are limited to a detection tolerance of approximately 1 per cent of pipeline flow – anything less may go unnoticed. Other leak detection methods – aerial surveys, optic fibres, acoustic monitoring, etc. – complement the online systems, but they also have significant drawbacks, including high retrofit costs and poor location accuracy.
In-line inspection (ILI) using ‘smart’ pigs can provide early warnings of leaks, by detecting damage before it leaks, but smart pigs can struggle to detect very small pinhole defects or accurately size defects with a depth greater than 80 per cent of the pipe wall thickness.
According to a May 2007 CONCAWE report, these limitations are reflected in the fact that 51 per cent of leaks in liquid pipelines, and 42 per cent of leaks in gas pipelines, are presently first detected by third parties, such as passers-by, and not by the industry’s leak detection methods. As an industry, our task is to improve these statistics and ensure leaks are detected more rapidly and effectively by technologies. One solution Penspen has identified is the use of dogs.Article continues below…
Research to date
Since 2007, Penspen, Manchester Jetline, and Newcastle University have been researching the feasibility of using dogs for leak detection. The results gathered during the research verified and quantified the dogs’ accuracy and reliability in locating a leak on a pipeline. The results confirmed that trained dogs can be deployed along pipelines as a reliable and accurate leak detection tool; a dog is 96 per cent reliable in detecting leaks as small as 0.07 ml.
How it works
Each dog is initially trained for six weeks to become a professional pipeline sniffer dog. The training is based around a single ‘target’ scent (for example, jet fuel). The ability to detect this scent is forever imprinted on the dog, but they have the ability to detect multiple scents: training the dog to detect another scent (for example, diesel) takes another two weeks. This means a pipeline operator can send samples of its product to a specialist trainer who would teach a dog to detect the target scents, confirming the dog’s reliability and accuracy in locating the product before it is deployed by the operator.
The actual field work is simple: the sniffer dog and handler conduct an above-ground survey along a pipeline right-of-way, similar to a line walk. The location of any escaping, or stagnant product is quickly pinpointed by the dog.
Recent industry success
Recently, a United Kingdom pipeline operator wanted to re-use a pipeline that had been out of service for a number of years. The pipeline had been in-line inspected 18 years ago, and deep corrosion had been reported. Consequently, there was a high probability of pinhole leaks being present in the pipeline after these 18 years.
The operator wanted to conduct an ILI before bringing the pipeline back into service, but decided it was prudent to check that there were no leaks using sniffer dogs. The operator recognised that ILI tools cannot detect pinhole leaks reliably, but a dog can.
The preferred dog, Blitzen, was quickly trained and calibrated by its owners, Dog Detectives, on the scent of the product, and confirmed that there were no leaks along the pipeline. Furthermore, the ILI tool reported that there were no throughwall defects along the pipeline (i.e. no leaks).
This case study has confirmed that trained dogs can be deployed as a routine inspection method, or run in parallel to any scheduled ILI to fully evaluate and confirm the integrity of any pipeline.
Pipeline sniffer dogs could have a major role to play in the integrity management of onshore pipelines, particularly in the following areas:
- Routine inspection, as part of an integrity management plan
- Cases where deep corrosion has been identified by ILI, and a verification of ‘no leak’ is needed
- Cases where coating problems have been identified by above-ground surveys
- Unpiggable pipelines
- Direct assessment
- Locations with poor cathodic protection coverage
- Cases where there are suspected ‘illegal taps’ and theft
- Following a hydrotest (where water has been scented and the dog can locate any leak).
Penspen’s on-going research with Newcastle University and recent work within the oil and gas industry has shown that dogs can be successfully implemented as a reliable and accurate leak detection tool. They can detect very small leaks both during operation (and hydrotest), and can be used to detect illegal taps. Finally, they are highly cost effective, environmentally-friendly, and remarkably easy to train and deploy.