Exposed PipelinesDig Safely Home< BackNext >

 

It’s critical to support and protect exposed Duke Energy natural gas or propane pipelines.
Pipelines that are exposed due to construction activities can shift, separate, or be damaged when they are not adequately supported by the soil around them. Supporting and protecting these pipelines ensures their continued safe operation, and helps protect your crew and the public from the very serious risk of a fire or explosion. Below are some general guidelines for working around exposed lines; please contact Duke Energy for specific recommendations for your jobsite in Ohio and Kentucky.

There are several ways to safely support exposed pipelines.
Please click here to view and download technical illustrations of proper support methods. The best method for your jobsite depends on the type and condition of the pipeline, the depth of construction activity, and the surrounding soil.

 

Whether you utilize supports from above or below, the allowable length of pipe between supports (the “free span”) is determined by the pipeline’s diameter. Smaller diameter pipes are less rigid and therefore have a shorter allowable free span. Please contact Duke Energy’s Gas Engineering Department for specific distances.

When determining the free span you must consider the surrounding soil conditions. The edge of the excavation area may erode or slough off over time, and the free span can become much longer as the project goes on. Therefore, start with the smallest allowable free span possible when installing supports, especially when working in sandy or loamy soils.

Once pipelines have been supported, exercise caution when working around them:

  • Do not walk on, climb on, strike, or attempt to move exposed pipelines. Even a slight impact or load can separate pipeline joints, damage protective coatings, or destabilize supports. In addition, if you walk on the pipeline you are likely to deposit a residue on its surface, which can lead to corrosion. Please DO NOT walk on the pipeline during repairs or during new construction.
  • Protect the pipeline’s coating. The coating on the pipeline is critical to preventing corrosion. Any wooden beams in contact with the pipeline must be structurally sound and free of nails, and they must be removed prior to backfilling. Cover or pad any support material.
  • Slings must be made from nylon and in good serviceable condition. Each sling shall be properly rated for the load. All slings must be carrying equal loads at intervals no greater than the maximum allowable span of unsupported pipe. The slings must be made taut before excavating below the gas main.

Check regularly for damages.
Check the pipeline regularly for nicks, dents, or other damage. When your excavation work is complete and before you backfill around the pipeline, check it again. Even a minor nick or scrape can lead to future corrosion and/or gas leaks. Duke Energy must be informed if you find any of the following:

  • Nicks, dents, gouges, cuts, scrapes, or scratches in the pipeline coating or pipeline wall.
  • Damage to any wires attached to the pipe. (These are necessary to control corrosion.)
  • Damaged valve boxes.
  • Broken locating wire (on plastic pipes).
  • Damaged pipeline coating or wrapping.

Backfill with pipeline safety in mind.
Before you backfill, make sure rocks, pavement, sharp objects, trash (including paper), debris, wire, or other materials that could damage gas pipelines or interfere with the accuracy of future locates are not buried in the trench. Remove large chunks of hard-packed clay or dirt.

Well-compacted fill helps prevent stress and shearing forces on the pipe, so as you backfill, compact all fill underneath and around gas pipelines and fittings. Ensure that the top of the pipeline is covered by a minimum of 12 inches of fill material prior to the use of any mechanical compaction equipment. Hand tamp around any fittings where mechanical compaction cannot be used.

Please contact Duke Energy prior to using any high-energy compaction equipment. Impact-type compaction equipment is not approved for use over plastic pipelines. In these cases, controlled density type backfill is acceptable to use in lieu of compacted fill.