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Posted on August 31, 2016 3:08:15 PM
  • Jorge Marciano - Shawcor Pipeline Performance Group, Argentina
  • Publication: World Pipelines Magazine, July 2016
  • A comparison of Pipe-in-Pipe (PiP) and continuous manufacturing techniques.

New opportunities have appeared in Argentina over the last few years, regarding unconventional shale oil and gas and tight gas development in the Vaca Muerta oilfield, Neuquén.Shawcor plays a key role in this development with a large portfolio of products and services. Leveraging a wide range of capabilities, Shawcor is introducing solutions to the area with an aim to improve production.

Flow assurance is one of the most critical challenges facing oil and gas producers today – both onshore and offshore. The formation and deposition of paraffins, asphaltenes, hydrates and scales in wells, flowlines or processing plants is a very real problem that can significantly influence the profitability of onshore/offshore operations.

Similar to conventional oilfields, oil and gas extracted from unconventional oilfields can also have very high paraffin content. In some unconventional hydrocarbon basins, the critical temperature, or the temperature at which these paraffins begin to deposit and reduce the flow of hydrocarbons, is higher than that of conventional hydrocarbon basins. Therefore, it becomes imperative to minimize heat losses along the entire flowline. In order to improve transport efficiency, polyurethane foam (PUF) thermal coatings are used to insulate these flowlines both in onshore and offshore facilities – although this technology is limited to shallow waters up to 100 m depth offshore. With the appropriate design, these coatings are able to thermally insulate flowlines so that the hydrocarbon being transported stays above its critical temperature for the entire length of the pipeline.

Pipe coaters have typically prepared their facilities to thermally insulate pipes using a pipe-in-pipe process technique (PiP). Pipes fabricated for thermally insulated oil transportation using a continuous manufacturing technique are being introduced in Latin America. With an aim to gain
productivity, efficiency and quality as well as reinforcing its commitment to safety, Shawcor decided to incorporate a continuous process in one of its facilities in Argentina.

The purpose of this article is to make a comparison between the two manufacturing systems, discuss the parameters involved in each process and cover advantages of the continuous system. And, finally, set the parameters that should be considered when designing a coating for a given application.

The Coating

This system consists of three components:

  • Anticorrosion coating: could be a fusion bonded epoxy (FBE) or a three-layer polyethylene (PE) or polypropylene (PP) depending on the customer’s request.
  • Thermal insulating coating: rigid PUF with low thermal conductivity and good mechanical resistance.
  • HDPE jacket: it works as a barrier to moisture and mechanical protection of the PUF.

The foam is a two components formulation: polyol and isocyanate. The polyol largely defines the final properties due to containing the blowing agent, catalyst, foam stabilisers and other additives.

The production of thermally insulated pipes for onshore hydrocarbon transport requires a tailor made formulation in order to comply with all the properties and specifications established by oil companies as well as the European Committee for Standardisation’s EN 253 standards. These properties are: low thermal conductivity, small cell size, high content of closed cells, low water absorption and sufficient strength to resist the pipe’s weight and in-service stresses, i.e. good compression resistance, axial and tangential shear.

Process Techniques

Conventional process: PiP

Themal Insulation PUF - 2

The PiP process technique.

The pipe in pipe technique consists of filling the cavity or annulus between two concentric pipes, a steel pipe with an anti-corrosion coating in the center and a polyethylene extruded pipe on the outside, with a polyurethane rigid foam. The pipes are placed on an inclined table and the foam is injected filling the entire cavity/annulus by gravity.

During the injection, pipes and PE casing are kept concentric using polypropylene or polyurethane spacers in order to ensure homogeneous foam thickness. Also, caps are put at the ends of the pipes to contain the foam and guarantee complete filling of the cavity.

The amount of raw material is a function of: machine flow, length of the pipe and final density desired. Nevertheless, final distribution of densities along the pipe is defined by: the table’s angle, the temperatures of the components, pipe and PE jacket and PU kinetic. 

Themal Insulation PUF - 3

ContiLine - coated pipe with PUF before the external layer HDPE application.

Themal Insulation PUF - 4

ContiLine - stage of PU injection before the pipe entering into the mold.

This is a manual and hands-on process prone to many flaws, which ultimately determines the productivity of the process as it is limited by the number of tubes per injection. In addition, it is important to note that for a given foam formulation this process doesn´t always generate reproducible, or the expected, foam properties. Environmental conditions may generate non-homogeneous densities along the tube which may result in higher raw material consumption in order to ensure the annulus is completely filled. Finally, the fact that this is a manual and hands-on process means it is labor intensive which ultimately requires a larger workforce increasing the Environmental, Health and Safety risks of the team during the operation. 


Learn more about the new technology - the ContiLine concept and methodology and how it doubles the production speed of the PiP process by downloading the full article.

Shawcor's Pipeline Performance Group has incorporated the latest technology in this type of coating process and continuously addresses challenges in unconventional resource development with new solutions. In addition to PUF thermal coatings, we offer a wide range of internal coatings to meet the most demanding operations, corrosive fluids, and abrasive conditions, thus significantly extending the life of the pipeline.


Topic Highlights:

In certain hydrocarbon basins, the critical temperature can be higher than normal, so minimising heat losses along a flowline is crucial. To improve transportation efficiency, PUF coatings for thermal insulation on pipes can be implemented.

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