Custom Engineering: Case Studies

Trinidad and Tobago 56” Cross Island Project

The Challenge

The 56” Cross Island Pipeline (CIP) Project for the National Gas Company of Trinidad and Tobago Limited (NGC) is the largest natural gas pipeline in the Western Hemisphere. The 56-inch CIP system transports 3.8 Bcf/d of natural gas. The contractor, Bechtel International, encountered a number of challenges during the construction phase of the project. Buoyancy control for such a large diameter pipeline is significant and PipeSak Inc. was asked to play a significant role in helping Bechtel to simplify some rather difficult areas of terrain on the project. Bechtel turned to PipeSak Incorporated for a proposal and review of the project’s technical requirements. Bechtel had decided early on that iron ore would be used as ballast in the PipeSak. Iron-ore has a density greater than normal stone, thus a custom design was necessary.

PipeSak’s Solution

PipeSak engineered and delivered to Bechtel a finished weight to hold 14,000 lbs (6350 kgs) that still maintained a 4x safety factor. The iron ore used by Bechtel, although fine, set-up very well in each PipeSak, giving a finished weight of 14,250 lbs (6464 kg).

Bechtel quickly proceeded with filling and installing PipeSak in areas that required buoyancy control. PipeSaks were filled in a nearby yard and trucked to the site. Excavator operators required only a short training period to become familiar with the extra heavy weights, but once comfortable they installed the PipeSaks quickly and safely. One added benefit of using a geotextile fabric weight or saddle weight such as a PipeSak is that the overall installation costs are typically much lower than any other method of pipeline buoyancy control.

Wood Buffalo Pipeline PipeBags

The Challenge

Alberta oil sands presents oil producers with unique challenges - extraction, refining and/or transportation. Enbridge came to PipeSak Inc. for a custom engineering solution when they encountered their challenge of wanting to twin one of their existing pipelines. They found the terrain this new line would cross through wouldn’t allow for the use of standard weighting methods. The pipeline was to be buried in solid rock trench crossing a river. The width of this trench couldn’t be dug to the standard width of 45” for a 30” pipe due to the rock, so standard weights couldn’t be used due to the limited clearance on either side of the pipe and trench wall.

PipeSak’s Solution

To address terrain logistics PipeSak Inc. designed the PipeBag™. The PipeBag, essentially a longer PipeSak, would offer the same set-on technique as a standard size PipeSak. The new design would consist of two large cylindrical saddle weights that would sit on either side of the pipeline, essentially wedging them in between the trench wall and the pipeline. The PipeBag was designed with the same standard 4x safety factor that the original PipeSak weight follows. The design was tested for strength and durability. Each PipeBag could be picked up using one of two loops located on either end and the PipeBag draped onto the pipeline easily. PipeSak Project Managers oversaw PipeBag filling and installation for this custom designs to ensure they were filled to proper weight and then installed correctly to provide the negative buoyancy that Enbridge required.

PipePillo™ for In and Out of Trench Structured Pipeline Support

PipeSak engineers developed and then launched the PipePillo structured pipeline pillow (SPP) in 2011.

The Challenge

PipePillo stems from the pipeline construction industry’s need for secure support for buried pipelines. The pipeline industry was building larger diameter pipelines with thinner wall thicknesses (high D/t ratios) and risks of ovality and denting sharply increased.

The PipePillo product criteria was based on our experience in the field and what owning companies and contractors had told us they wanted for an in-trench structured pipeline support. The PipePillo has contoured frustoconical inner and outer supporting walls that transfer the enormous size and weight of pipelines.

The Structured Pipeline Pillow (SPP) has evolved since it’s initial design into a multi-functional tool with both in-trench and out-of-trench support applications. The SPP design was initially based on the following criteria and the PipePillo was then successfully designed to meet these requirements;

  1. Light enough to be handled individually with a maximum weight of 18 kg (40 lbs).
  2. No one required in the trench for installation.
  3. Resists floatation.
  4. Strong enough to hold a pipeline filled with hydrostatic test water.
  5. Stackable for easy transport.
  6. Contact area with the pipe surface should be porous enough to allow free flow of groundwater and cathodic protection currents.
  7. UV resistant.
  8. Resistant to a wide range of chemicals (pH) found in soil.
  9. Pipe clearance off the bottom of the trench must maintain for the life of the pipeline.
  10. Inner cavities accessible to soil inflow over the long term.

PipeSak’s Solution

The PipePillo structured pipeline pillow (SPP) was engineered to be the pipeline construction industry’s answer for in-trench pipeline support. The PipePillo permanently supports and suspends pipelines above rocky trench bottom. PipePillos are injection-molded and made from high strength, long lasting, and environmentally inert polyethylene that is treated for extreme UV exposure. Custom designs and variations on the commercial PipePillo design for pipe support are available and can be developed upon request.

Compared with the other current support techniques PipePillo:

  • is stackable and easy to transport;
  • is lightweight for installation from outside of the trench and won’t float out of position when groundwater is present;
  • ensures the pipeline is centered in the trench;
  • won’t obstruct cathodic protection systems;
  • won’t biodegrade;
  • addresses concerns over ovality/denting; and
  • maintains long-term pipe clearance above rocky trench bottoms.
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PipeSak® is a registered trademark of PipeSak Inc.
PipePillo™ (patent pending) is a trademark of PipeSak Inc.
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