Subsea installations are a major investment. The amount of time and money it takes to…
It may be too soon to start talking about Christmas, but holidays are a year-round annoyance for the oil and gas industry.
We’re not talking about the festive season spent with family and friends, of course, but about the defects known as “holidays” that can appear as the result of damage or human error in the pipeline coating application process.
As you know, the substrate materials that make up pipes and other underwater structures must be protected from the corrosive effects of seawater. There are many pipeline coatings and splash zone protection options available to accomplish this, but if they aren’t applied just right, defects such as such as pinholes, discontinuities, and improper bonding can appear.
When these “holidays” appear on the coating on the substrate material surface, they aren’t always easy to detect without the aid of precise electrical measurements. The damage can quickly snowball, however, from microscopic to catastrophic.
Gouge in pipeline coating (courtesy of the South Dakota Public Utilities Commission)
Avoiding holidays starts with properly coating the pipe, which means preparing a pipe surface by cleaning, sandblasting, and preheating it according to the specifications of the coating manufacturer. Applying the coating may also require shielding to prevent moisture and dust contamination.
Surface preparation affects the performance of the coating more than any other variable. Think of it like the foundation laid before constructing a building. If you start with a weak foundation, the building will collapse sooner than it should.
You must first establish an “anchor pattern” on the surface of the pipe as the coating won’t easily adhere to a smooth surface. Those tiny peaks and valleys that make up a proper surface profile (anchor pattern) give the coating something to cling to.
Ensuring the pipe is free from all contaminants (both visible and unseen) is another important step. Oil, grease, and even fingerprints can create unwanted irregularities in the coating process.
Soluble salts such as chlorides and sulfates are invisible but, if left on the pipe surface during coating application, can draw moisture through the coating and cause blistering and eventually detachment. That’s why it’s critical that you thoroughly clean the surface of the pipe with a solvent before abrading it.
Click here to see the application procedure for SplashTRON® sleeves, which includes the use of an MBX Bristle Blaster to abrade the surface of the pipe. Bristle blasting is a process that uses a specially designed rotary bristle tool to remove corrosion and create an anchor profile.
The long and short of it is this: A top-quality pipe coating applied to an improperly prepared surface is no better than a cheap coating applied to an entirely clean, abraded surface!
Electronic holiday detection is also known as “jeeping.” It’s a process that sniffs out minute pinholes, cracks and other bonding defects before they become a larger problem. Pipeline owners, coating applicators and coating inspectors typically conduct an electrical inspection on fusion-bonded epoxy (FBE) pipeline coatings following shop application of the coating (but before installing the pipeline coating on-site).
Portable holiday detectors are used for pipeline, plant and other surface applications where the pipe is stationary. In-plant detectors work similarly, but the inspection surface moves past the stationary detectors. High-voltage detectors are most commonly used for thicker surface coatings, such as those used on pipelines and other industrial applications.
Need to know more? The Pipeline and Hazardous Materials Safety Administration cites common jeeping errors when inspecting new pipeline construction.
You should repair all holidays as soon as they are detected if the pipe is to remain in service. Consult the coating manufacturer to get repair recommendations. After surface preparation (cleaning and abrading), you will need to remove any abrasive particles trapped in the coating and the coating system re-applied to those areas. Don’t forget to repeat the holiday test after the repair work is complete!
Whether you need to coat your pipelines or re-apply coating where your pipes are vulnerable, Mark Tool and Rubber can help. Contact us today and let us know which of our products and services we can assist you with.