Visual & Sounding Inspections
Visual and sounding inspections are a reliable method of detecting pipes in an advanced state of distress.
Internal visual and sounding inspections require manned entry to the pipeline and dewatering of the pipeline. Typically, a visual and sounding inspection is conducted in parallel with an electromagnetic inspection. Using the data from both inspection methodologies, Pure’s Engineering Services team can deliver an accurate report on the condition of the pipeline.
Any pipes judged to be in a potential state of incipient failure will be immediately reported to the utility so that replacement or rehabilitation can be performed while the pipe is out of service for the inspection.
Visual and sounding inspections are performed by trained personnel in manned, confined space entry. For the manned entry, access manholes along the length of a subject pipeline will be used.
The visual portion of the inspection consists of observing visible features and cracks that indicate potential distress. This inspection requires experienced staff to know which cracks are normal and which are indicative of a problem. It also requires a thorough understanding of the width and length of cracks that are normally produced during the production of pipe as opposed to those that might indicate lack of prestressing, or distress, in the pipe.
The visual inspection will also include an examination of the joints as well as the width of joints or the amount of pull the pipeline was subjected to in order to maintain line and grade. All anomalies will be noted with the distance and location from known features. In many instances closure pieces, adapters, shorts, and other specials are inserted in pipelines to make station on outlets and other tie-in features.
Figure: Cracks on the interior of a pipe identified during a visual inspection. In many cases, cracks are not this obvious. A careful visual inspection is performed with people dedicated to the task and with considerable experience in these types of inspections.
The sounding portion of the inspections relies on impacting the interior surface of the pipe wall with a tapping rod and listening for hollow sounds that indicate delamination. Delamination is also an indication of a loss of prestressing in a pipe due to wire break damage.
Visual & Sounding internal inspections have the following capabilities:
- It is an excellent, proven method of finding pipe sections in a state of incipient failure. As wires break in a prestressed pipe, the pipe begins to expand. Since the concrete liner cannot expand, either a delamination or crack will form as the pipe approaches failure.
- Provides an excellent lay schedule of pipe that is in the ground; as-built records often differ from in-ground pipe conditions.
- Provides good documentation of the interior condition of the pipe. Dimensions and photographs of cracks are provided and joint problems are documented.
- Provides information on the condition of joints.
- Urgent anomolies reported immediately
- Find and locate:
- Cracks (latitudinal, longitudinal)
- Welding defects
- Loss of mortar coating
- Unknown pipeline features such as lost valves
- Inspection of valves