Why the Thick Coat?
The development of modern thermoplastics with specialized formulations that provide effective anti-corrosion properties for oceanic pipelines had an unexpected consequence. How to remove the coating that was designed to be tough, permanent and to stick to the pipe through the ravages of the deep ocean.
Plastics can be manufactured in an astonishingly wide range of finishes and chemical compositions. They can be brittle and super hard like polycarbonates, acrylics or acetals, or they can be soft and pliable such as polyethylene, high-density polyethylene, polyurethanes, and vinyl-based plastics like PVC.
The fact that most plastic formulations are based on petroleum chemicals gives them exceptional resistance to highly corrosive saltwater and offer a long life despite the harsh environment.
In addition to the coatings, durability is the important factor that the coating remains flexible to permit pipelines to flex, expand and contract. As many pipelines are laid on the ocean floor the coatings must provide effective anti-abrasion protection from rocks and sand that could significantly damage or destroy the pipe.
Finally, the tough thick coating serves to provide an efficient thermal barrier that ensures that the oil remains viscous enough to flow correctly in the frigid water depths that pipelines are run. The advent of deeper and deeper pipeline depths makes this an ever-increasing factor for maintaining proper transfer rates for offshore petroleum development.
The Coating Problem
So now that we understand why today’s oceanic pipelines utilize tough, thick coatings, what happens when you need to cut and weld coated pipeline sections. The coating must be removed back from the weld joint to allow the use of pipe facing machines for precision beveling to occur, a prerequisite for reliable and quality pipeline welding. Simultaneously, the coating removal process must prepare the area on either side of the weld joint for the subsequent injection molding of a plastic band that will be created to protect the weld area.
The coating placed on offshore pipe typically comprises several layers that may or may not be formed from similar materials due to the durability and thermal properties desired. These layers are “color-coded” to assist with the process with a tough outer and intermediate layer being formed around an “indicator” layer that signifies that the remaining coating is very close to the pipe.
Tri Tool Custom Engineering Solutions
Coating removal systems have been designed to provide form tool cutting (specially shaped tool bits), or by milling with an end cutting bit. The custom engineering team saw an opportunity to utilize one of our standard products, the clamshell lathe, to create a solution to this unique application. The clamshell lathe has proven to be an excellent platform for form tool cutting or milling with an end cutting bit. Our clamshell lathes offer exceptional mounting rigidity, precision, and optimal depth control to cut uniformly down to the critical indicator coating layer, making it an ideal solution.
Due to the diversity of materials and coating layers involved, most coating removal solutions must be configured for maximum efficiency for the project at hand. Tri Tool custom engineering has the experience and custom manufacturing support to specify, design and manufacture a coating removal system for your most demanding requirements.