There's a reason why CPAs are always in demand.
They took the time to read the tax code and condense it down to what you need to know.
The repair codes for pipelines are the same way.
Except there aren't any CPAs readily reading and translating the pages of a repair method and manual.
Let's change that.
This post explains what you'll see when you dig up a pipeline and ways to fix them.
General Types of Defects
Dents in a pipeline can be caused by rocks, third parties, or bad manufacturing. They can range from a shallow dent or a deep one that prevents tools from navigating through them.
Because of the way that dents occur, there are usually cracks within them. This makes these repairs high profile because while one defect is suspicious, a combination of them can mean a high risk consequence for the pipeline.
Cracks occur in the girth and seam welds of a pipeline. Think of it like a crack in the grout between the tile or a crack on your windshield. With temperature swings and different flows in the pipeline, they can become real bad real fast.
Mid Wall (Lamination or Fabrication Errors)
These features are commonly found in seamless pipelines because the rolling process sometimes causes wall thickness variation. You can't see these features with the naked eye and need special ultrasonic tools in order to find them. They interact with other features in a major way, so getting them repaired ASAP is always a good idea.
Corrosion can happen anywhere on a pipeline. Internal corrosion occurs when the product has microbes or another corrosive substance (water anyone?) running through it. Like laminations they aren't visible and can only be found by tools and UT inspection. Running additives that control the microbes or products other than water can mitigate this.
For easier to spot features, this is the most common. Corrosion can be connected or isolated depending on the area the pipeline runs through. Because it's so common corrosion is easy to mitigate. As part of the checks to the system you should check the cathodic protection as corrosion may be an indicator that it isn't working. Otherwise it can be due to moisture or other objects in the ground.
When dents or mechanical damage happens, a gouge is often paired with it. Metal is missing from the pipeline due to the equipment that took it away. It should be easy to see on the coating even before you blast it off!
Types of Repairs
The best part about repairing a pipeline is that many methods can be done (and some even require!) on in service pipeline. No operation changes need to be made.
Here's typical methods of repair and what type of defect they are used for.
Sometimes you need to slap on a fresh coat of paint and primer to prevent corrosion. These are the easiest repairs to complete and take relatively little time and extra equipment to do. Make sure you have the right epoxy and can mitigate the corrosion by checking your cathodic protection and surrounding area.
Sometimes a gouge or crack can be grinded out. This is not recommended for most repairs because it does take away metal. However, if the UT inspection is done thoroughly you can perform it with no issue.
Type A Reinforcing Sleeve
These repairs involve a sleeve that goes around the pipeline but is not directly welded on. While it is a great repair method that doesn't interact with the pipeline, it does present some issues if not performed correctly or if there are other factors such as cycling involved with the operation of the pipeline. These repairs are most likely a temporary fix for a Type B or full replacement to take place.
Type B Pressure Containing Sleeve
Type B sleeves are essentially welding another set of pipe to the existing pipe. You can weld on an in service pipeline due to the heat loss that occurs when there is product flowing. The heat loss can present challenges with the welding speed and cooling times, so a proper procedure and trained welders are key to performing the repair correctly. In addition, there are not many manufacturers of Type B sleeves, so having some on hand rather than waiting for the repair call is useful for speed of repair and return to normal operations.
Composite wrap repair
When recoating just isn't enough, you need a bit more protection from the elements. Composite repairs are the perfect solution when welding is not an option and you still need a way to eliminate corrosion or prevent further crack/weld damage from taking place. There are plenty of vendors for these type of wraps so there is less stress on having them on hand. However the application method varies - so training crew members on proper application is critical in completing a repair.
Full cylinder replacement (cut out)
The last resort for high profile pipelines is to shut down a line and take out an entire piece of pipe to replace with another joint. These repairs are welding intensive and require coordination on many fronts due to decomissioning and recomissioning the line. Welding material is crucial as well due to weld methods and proper inspection procedures. Before everything is tied up you'll need to make sure the welds are thoroughly inspected.
The difficult part about these repairs is getting the line down and working efficiently to reduce the business losses. As a project manager during these repairs its critical to communicate the status and identify roadblocks as early as possible
How to Determine the type of repair
Knowing is half the battle when it comes to the types of defects and repairs. How do we decide on what repair to move forward?
A few things can be taken into account as part of this process:
The mechanical codes and repair guidelines given by PHMSA, ASME, and company internal requirements are great references to go by. Most of the time they say the same thing, and are conservative guidance due to the high visibility of liquid product pipelines.
You can readily find these codes online or within the company manuals. As someone who was new to this coming in, the search function is your friend, and the calculations are straightforward to put into a spreadsheet for future reference.
Theoretical versus Feasible
While it's great to be conservative, you have to keep in mind what can be done for a repair. Pipelines don't just run through plots of land. They can go through swamps, bridges, rivers, schools, etc. that aren't easily accessible or allow for a full sleeve repair to take place. Working within the guidelines you can come up with creative solutions to repairs. Sometimes having to opt for a new trajectory of a pipeline or accepting a reduction to improve the life of the pipeline.
Do what makes sense with all your stakeholders. The best decision is one made with consensus and input from all key players.
Automating Pipeline Repair Methods
Since most codes and guidelines are similar, it makes sense to put the calculations and guidance found into easy to understand visuals and sheets that allow someone with less experience to get their feet wet on repair projects.
Two methods are described below
Hydraulic calculations, wall calculations, and weld speed calculations are all great formulas to have on hand. Developing a one stop shop for basic equations is a great idea that you can standardize, update, and pass on to the newest project managers.
Visuals allow one to teach themselves a thought process rather than having to tell them each time. For run of the mill defects, these work great as an outline of the logic that goes into repair calls. As the repairs get more specific, there come exceptions and other factors that come into play. These charts can be updated for exceptions as well as updated if repair guidance is changed. Condensing hundreds of pages of codes is no easy task, but can save you many hours of training new hires when the work is put in.
With each method its great to consult existing managers about their experience and allow them to make notes based on what they have encountered. Leverage the experience to make the tools available for posterity invaluable.
We scraped the surface of what pipeline defects are and how to fix them. Making them easy is a matter of condensing information into digestible and reusable tools that you can pass on and update as the industry evolves.
Sometimes repairs call for a cold eyes review to determine and plan. For extensive experience in pipeline repairs and methods, feel free to message and connect with me.