Thermal Grout
iSet-TGrout-M5 is a cementitious Thermal Grout primarily used to fill the inner annulus of a casing, encasing the conduits and all voids within the casing. iSet-TGrout-M5 Thermal Grout is generally installed within Horizontal Directional Drills, Micro Tunnels and Jack and Bores.
iGel-TGrout-M2 is a non-set Thermal Grout primarily used to fill the inner annulus of a conduit, encasing electric cables after they are installed and all voids within the conduit.
iSet-TGrout-M5 and iGel-TGrout-M2 Thermal Grout products are each designed not to exceed 65° C-cm/W @ Set-State. Each product can be pumped 100’-5,000’, and can be tailored to meet any project specification or requirement.
Thermal Grouting
inTerra is a national, full scope, self-performing thermal grouting contractor, providing:
- System design engineering
- Thermal Grout mix design engineering
- On-site Thermal Grout material production
- Installation of Thermal Grout within the system
- Risk mitigation for the system before, during and after Thermal Grout installation.
inTerra’s Services Team: An engineered approach, innovative technique and methodical execution.
Our meticulous approach to thermal grouting provides for the highest factor of safety in highly risky applications. In many cases, there is one opportunity to complete the operation with the exposure to liability in the millions. We hold this responsibility in high regard and have developed systems from engineering through installation which will mitigate the associated, inherent risks.
Our Thermal Grout is designed primarily to achieve a low thermal resistivity as dictated by high voltage cable manufacturers and electric utilities. However, our Thermal Grout must be pump-able over long distances without segregating or settling and cannot damage, crush, melt or otherwise compromise the system around which it is filling. inTerra’s product will optimize heat dissipation and will eliminate the common failures associated with Thermal Grout products and Thermal Grouting operations.
When an underground electric transmission line transitions into a Horizontal Directional Drill or a Jack and Bore (under a river or highway, etc.), the need for heat dissipation does not go away.
Opposed to open trench heat transfer solutions (Thermal Concrete, Fluidized Thermal Backfill) which are simply backfilled into the trench, Thermal Grouting is a complex process that must be engineered from start (mix design engineering) to finish (delivery within the casing). inTerra engineers superior thermal grouts and delivery systems eliminating the Achilles heal (hot spot) within the transmission line route.
Dense, thermally conductive grout is required to fill the voids within the HDD or jack & bore casing and around the conduits (which house the cables) or within the conduit around the cable. Thermal grouts can be cementitious or non-cementitious depending upon the specific use. The diagrams below, depict typical HDD, jack & bore or conduit grouting arrangements.
What is Thermal Grout?
Thermal grout is a combination of fine aggregates with heat transfer properties, water, additives, and cement or bentonite designed to stay in suspension during and after installation to maintain the integrity of the original mix design and thus heat transfer properties. The specific combination of ingredients is, among other factors, tailored for:
- Pumping over long-distances (1,000′-5,000′) within tight spaces
- Filling the annulus of a casing with a crowded conduit system
- Providing resistance to the conduit system during cable pulling
- Most importantly: optimal heat transfer to protect costly power cables
For more about the need for thermal protection around electric power cables, see “Thermal 101”.
Why is Thermal Grout Tricky?
Harmoniously balancing density, fluidity and the ability of the grout to stay in suspension while traveling through tight voids and at long distances is a difficult yet critical task. Pumping a thick, viscous, heat transfer material in these conditions can easily create internal pressures high enough to deform the conduits inside an HDD or jack & bore. The result can easily be that the conduit bundle is rendered useless, and a complete extract and rebuild is the only solution.
Thermal grouting is a bid item that is often overlooked and addressed when it is too late, and when the wrong conduit, spacers, strapping, welding and other items have already been specified, purchased and assembled into a conduit bundle. This is a costly mistake you can ill afford to make.
Thermal grout installation must be meticulously engineered prior to construction and in strict coordination with the drilling and/or electrical contractor to best mitigate the inherent risks associated with delivering a high density — low thermal grout within a closed environment housing the expensive high voltage electric transmission cables. Trying to “bull” your way through this sort of grouting project is a recipe for a very expensive disaster.
Why inTerra?
inTerra has the experience to work seamlessly with all parties involved from the design phase through construction to help mitigate potential risk of an inherently risky task, by providing recommendations on the conduit bundle system and material selection to ensure the system can withstand the grout delivery process.
inTerra is expert at sourcing thermal aggregates and conducting pre-design assessments in remote locations throughout the world, ensuring that the materials selected are functional for the project from a thermal and flow-ability/pump-ability standpoint, yet are not cost-prohibitive. To complete the design and ensure the thermal properties adhere to the specification, we retain the third party services of Geotherm, Inc., the world-wide leader in thermal design. Combining our lab and field expertise with Geotherm’s prowess ensures an optimized thermal grout that is able to be pumped at the long distances and in the tight spaces often required.
inTerra also devises comprehensive grout manufacture and delivery systems to ensure that all voids within the casing are filled with grout so that the cable can perform at its’ design ampacity. We work seamlessly with drilling contractors and electrical contractors to help mitigate the inherent risks associated with thermal grout delivery.
With virtually no margin of error, inTerra is dedicated to ensuring the success of thermal grout installation in the design phase as opposed to reacting to the many mistakes often made due to the industry’s lack of knowledge.
inTerra is a national specialty contractor and construction materials provider focused on innovative solutions for the design, manufacture, delivery and installation of products within the utility, renewable energy, geo-technical, heavy-civil and infrastructure industries.
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