A. Design
TransGas pipelines and related facilities are designed to national standards using quality materials and equipment. Our trained staff work hard to find economical solutions for our customers. TransGas works closely with our pipeline suppliers to ensure the production of top quality steel pipe. For each project, the correct grade and weight of pipeline is selected according to national standards.

All pipes are coated with a protective covering, such as epoxy and polyethylene, before installation. Epoxy coating is fused and polyethylene coating is extruded or melted onto the bare steel pipe, providing the steel pipe with a first line of protection against corrosion. In the past, asphalt, coal tar and tape were used as pipeline coatings.

Another means of defence against corrosion is the design and installation of cathodic protection systems.

B. Grading & Trenching
The surface right-of-way area, located on both sides of the pipeline will be, is carefully prepared before installation begins. Topsoil is stripped off the area of trench construction using soil preservation techniques and piled on the right-of-way until after construction is complete. Once complete, the topsoil is carefully replaced and the terrain is restored to its original state.

Right-of-Way Preparation

Trenching Operation – Ditcher

A trench, approximately one metre deep, is dug using a trencher or other suitable excavation equipment.

C. Stringing/Bending/Welding
Segments of pipe approximately 16 metres in length are shipped to the construction site. These segments, called joints, are laid out, end-to-end on pipe stands along side the trench. Where required, a pipe joint is bent using hydraulic equipment to form the pipe to the lay of the land.

Welded pipe segments

Each joint is then welded together to form one continuous pipeline. Certified welders do all welding according to strict TransGas weld procedures, industry specifications and National Standards.

Once each weld has passed radiographic inspection, each weld seam is coated with a protective sleeve (similar to polyethylene coating), protecting the pipeline material.

D. Lowering-In & Backfilling
Construction workers use sidebooms to lower the pipeline into the trench. In locations where the trench bottom may damage the pipeline coating, a layer of sand is placed on the bottom of the trench to protect the pipe and it’s coating.

Lowering-In Operation

The pipeline is then backfilled using as much original dirt as possible. If the original material contains larger rocks, it may not be used as backfill. Rocks cannot be placed directly on a pipeline as they may damage the coating or even the pipeline steel. If using the original material isn’t possible, an extra protective coating called rock shield is applied to the pipeline surface prior to backfilling.

Backfilling

All TransGas pipelines are designed and installed to have a minimum ground cover of 1.0m.

E. Crossings & Tie-ins
At roads, railways and waterways, specific techniques are used to minimize surface damage and enhance safety. We drill a hole underneath these crossings and then pull our pipe through this hole. One method of drilling is using a direction drill unit (directional drilling). Once complete, we weld this section of pipeline to the rest of the pipeline. This technique minimizes any adverse affects to the road, railway or waterway.

For added protection, thicker walled pipe is used to make the pipe withstand any extra weight at these locations. Also, there is a minimum of 1.5m of cover under roadways and 2.0m under railways and waterways.

Directional Drilling

F. Pressure Testing
Following installation of the pipeline system, pressure-testing operations commence. Pressure testing allows our engineers to ensure the pipeline is safe and ready for operation. Under normal circumstances, the pipeline is filled with water and raised to a pressure higher than the maximum operating pressure of the pipeline. All testing is done in accordance with National Standards and Provincial/Federal regulations and is approved by a Professional Engineer.

G. Control Valves
Approximately every 30 kilometres, control valves are installed on the pipeline. Should a leak occur, pressure in the pipeline will decrease, triggering these control valves to close automatically or manually by operations personnel dispatched from our Gas Control centre. This decreases the total amount of escaped gas and ensures safety.

H. Clean Up
Restoration of the right-of-way is conducted, together with TransGas Environmental Affairs Department, for the entire length of the pipeline. Returning the terrain to as close to the original condition is always the goal. The topsoil originally removed during the grading process is returned and then seeded where appropriate to do so.

Right-of-Way Restoration