If you’re running pipes full of oil, you need to be a world-class risk manager. Take Canada’s Enbridge, which transported 14B barrels of crude over a decade with a “safe delivery record” sitting at 99.9993%. That impressive percentage is still 0.0007% too low for their liking.

Oil leaks damage the surrounding environment, throw work schedules and budgets out with emergency repairs, and threaten the business’s reputation. One way Enbridge keeps the number of emergencies down is through preventative maintenance digs (or ‘integrity digs’).

Preventative maintenance digs do exactly what the name says.

• Preventative – by working on pipes before they leak, bigger problems are prevented.
• Maintenance – the work done maintains the current pipes, restoring them to the way they were rather than making any changes to the network.
• Dig – unlike automated inspection, this work is done by people who dig down to the pipe and work on it directly.

While Advanced Piping Systems supplies pipe that is almost always destined for an above-ground installation, you can still apply the principles from this article to your pipeline.

Monitoring is essential, but seeing is believing

Enbridge scans pipes internally with in-line inspection tools. As the company explains, ‘when an in-line inspection finds something that requires a closer look, we excavate the pipe…examine it and make any necessary repairs.’

Typical issues fixed through preventative maintenance digs include:

• corrosion
• cracks
• dents
• external damage.

First steps: Taking a proper look

Preventative maintenance digs at Enbridge start by stripping away the topsoil. This is stored separately from the subsoil, which is usually dug up with a backhoe.

Workers then clean the pipe and remove its coating to begin inspection. The next steps depend on what they find.

No news is good news

The first possibility is that nothing needs fixing. All that’s left to do is to recoat the pipe and undig the hole.

Enbridge still sees value in digs like this. As they put it, every visual inspection “adds to our overall knowledge about the line’s condition”.

For land-owners, CAEPLA’s Pipeline Observer blog suggests that preventative maintenance digs are like medical check-ups. ‘Similar to a CT scan that ends with no tumour, you can focus on the relief.’

Bad news is also good news

On the other hand, preventative maintenance often identifies some repair or replacement work to be done. This is a win for your inspection process! A little bit of work now is going to save a lot of work later.

Preventative maintenance is safer, cleaner, and cheaper than dealing with a leaky pipe. It also adds to the pile of emergencies that you’ll now never have to deal with.

For buried pipes, it also means that you’ll be putting back in place a stronger, better quality pipe.

Repairs and replacements

If the pipe does need work, that could be anything from cleaning and coating a bit of corrosion to removing a section and welding in a replacement length. Work can take a couple of days, or as long as a fortnight.

Whatever work is done, tests follow to make sure that everything is to standard. The pipe is recoated and then everything is covered up again.

Putting things back the way they were

Once the pipe is fit for service the excavation is backfilled, topsoil returned, and the site cleaned up. In buried pipelines, the aim of a preventative maintenance dig is to leave everything the way it should be.

Enbridge’s 99.9993% record of safe delivery shows that they’re a world leader in oil pipe maintenance. By learning from their practices like preventative maintenance digs, you’ll begin to see how many 9s you can line up in your own reports.

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