Eml Vs Gpr Surveys In Ireland For Pipeline Testing

By Author: Danniel Kollen
Total Articles: 22
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In Ireland and the UK, the PAS128 survey is the BSI standard for underground utility detection specified. The survey amasses both EML and GPR surveys to trace subsurface utility apparatus to specific depths. The technologies and their mechanisms are much different from one another. But they have one thing in common: they both use signals transmitted into the ground to locate objects. For most of its part, both the technologies have vital features that don't let the modern equipment outdate the traditional one.

Application and Importance of EML and GPR Surveys in Ireland

EML detection wands are considered industry-standard tools in Ireland for detecting conductive pipes and cables when used in conjunction with a signal generator.

These wands detect shallow and deep infrastructure using a variety of frequencies, but they are essentially 2D locators. To detect underground infrastructure, they work well because the pipe or cable must be easily accessible and conducive to generating a signal.

In a trade-off test with no manhole access, Ground Penetrating Radar will recover the locations ...
... of more underground features than Electromagnetic Location methods.

During a GPR survey's site reconnaissance phase (which involves lifting manholes and identifying services), information is recovered as part of the process of clamping onto services to induce a signal, which is typically done in conjunction with an EML survey. Also, EML uses a known signal that is then traced to enable services to be positively identified and tracked as opposed to simply being located by GPR.

Parameters That Determine Which Device To Use in Pipeline Testing

The core outline to determine the selection of equipment of course is based on the purpose of the mapping, but on the technical front, it also includes the following.

• Whether it is to pinpoint the location of the pipelines, record the information or mark on the ground

• The nature and material of the underground asset - whether plastic pipes, concrete or metal.

• Nature of the pipeline and duct internals - whether it is empty or hollow or has any anomalies present.

When detecting power cables and other utilities is the primary goal, the EML technology can be the best option to choose. When used correctly with all modes and a transmitter, the EML locator can detect power cables even if there is no flowing current in them. However, using EML locators around non-current-carrying cables can make excavation difficult. Damage to power cables is a new threat. It may lead to larger disruptions that may even require excavation of the site. A humongous expense and hazard for the site owner to bear. Because it can detect both metallic and non-metallic targets in the same scan, GPR has a better chance of recovering the locations of more underground features than EML.

Pipe Penetrating Radar for Pipeline Testing

Pipe penetrating radar (PPR) is a new technology employed to detect anomalies around and within the diameter of pipelines. Underground pipes made of various materials, such as PVC, concrete, vitrified clay, and HDPE, can be detected using this method. PPR can map areas outside the pipe that are filled with air or water to some extent, unlike GPR, which can only map non-ferrous pipe walls, pipe bedding, and conductive soil.

The Surveyor usually uses a pair of PPR antennae. These can be set to collect information from any two clock positions between 9 and 3 o'clock. Lines of data are collected from two clock positions as the robot moves in one direction, and two different positions as the robot return to the deployment point, in a typical survey. With just one deployment, four lines of PPR data are generated. The PPR antennae on the Surveyor operate at 1.6 GHz or 2.3 GHz, with a signal penetration depth of up to 920 mm.

The Importance of Utility Characterisation

The feats of a successful utility survey must characterise the utility as a specific service, particularly with regards to finding evidence and justification for each action. As a result, engineers can carry out fieldwork more confidently, knowing that the detected utility is also identified well and good.

So as an engineer looks at a picture of an electric cable, they can rest assured that the structure is indeed an electric cable. The mitigating factors surrounding misidentification of other utilities, on the other hand, mean that any utility, unidentified utilities or those identified by power or radio (indirect methods), should always be considered as a potential hazard.

Author Bio:

The author takes the onus to answer this popular query that many clients have when choosing between the EML and GPR surveys in Ireland. These are both significant for various pipeline testing and other underground survey parameters. Get insight from experts.