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
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
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.
Trenching Operation Ė Ditcher
A trench, approximately one metre deep, is dug using a trencher
or other suitable excavation equipment.
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
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
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 isnít possible, an extra
protective coating called rock shield
is applied to the pipeline surface prior to 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
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
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
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.