Frequently Asked Questions

Your questions answered

Q: We can't survey where the pipeline goes under a road. Can survey this section?

A: Yes. It can survey over any tarmac/blacktop. If the traffic is active, you can take a reading either side of the road. This will give an indication of the coating quality across the road.

Q: There is a field with cattle in. We don't want to survey in there as the wire (CIPS) will get broken. How can we survey this field?

A: You can either take the into the field, or if the cattle are not 'friendly' you can take a survey point either side of the field. This will tell you if you need to go into the field to find any fault that is indicated.

Q: Our pipeline goes across a marsh that is always in at least 8 inches (20 cm) of water. Our present method cannot survey here. Can do it?

A: The is completely immersion proof to about 2 feet (600mm). So yes you can survey here.

Q: We have two parallel pipelines that are cross-bonded. However we cannot find one cross-bond. How can we find it?

A: Walk between the two pipelines with the . When you pass over the cross-bond the will show 'overhead'.

Q: We have a problem surveying two parallel lines that are so close they are touching and the cross-bonds are buried. How do we survey this?

A: If the pipes are that close and are cross-bonded, you can treat both pipes as one. Do a survey as normal. Any faults that are found could be on either pipe. It is not possible (by any method) to distinguish between these two pipes. It would, however, be impossible to excavate only one of the pipes!

Q: Our pipeline crosses another (not ours). How can we tell if they are touching?

A: If the pipelines are cross-bonded, disconnect this. Survey on your pipeline. If you get a fault in the crossing area, take another reading on the other pipeline. If you get a reading, the two pipelines are touching.

Q: We suspect that a pipeline we have been contracted to survey has sunk due to wet ground. This could be placing a strain on the pipeline. How do we check this?

A: Take depth readings along the pipeline section. This will show any bowing and by how much. You can use the 'close interval mode' on the 2010 for this.

Q: We need to make a map of the pipeline we are surveying. Is there any way of doing this?

A: As the 2010 has a built in GPS unit (you can use an external GPS with the 2000 unit), the report made by DCAPP, has a GPS plot. You can either scale this plot and overlay it on your map or you can take the latitude and longitude readings (also printed out) and input this to a GIS system.

Q: Our pipeline has an IJ. How can we survey this?

A: An IJ will interrupt the current flow, so you can either bridge it out if you need to do a continuous survey, or you can connect one side to a convenient ground point and survey up to it. If the IJ is not bridged or grounded, surveying will show increased attenuation as you approach the IJ. This is because the current leaves the pipeline before the IJ.

Q: We have been using the 2000 and we have a problem. When surveying a pipeline in very high resistance ground (desert). An injected current of 800mA, using a CP ground bed as earth, cannot reach the first test post (1 km away). How can we possibly survey this pipeline if the signal cannot go this far (we lose it all after about 200m)?

A: This indicates that you have a serious fault within the first 200m. If the attenuations are all high then the coating is completely gone and surveying the pipeline is a waste of time as it is all faulty (at least the first 200m). If you only have one very high attenuation then there is a very bad fault in that place. Fix this first before continuing to survey. This fault will stop the CP from doing its job on the rest of the pipeline and is therefore important that it is fixed as soon as possible.