Features of the training centre
The main pipeline is 2" dia. thin wall, mild steel pipe welded into a pipeline 50 meters long.
The total electrical resistance of this pipeline is 0.186 ohms and it therefore represents
a 36" dia 1/2" wall steel pipeline 1500 long in electrical circuit terms.
The main pipeline has three types of coating.
Raychem shrink coating applied over specified two part primer
applied by experienced coating team with Raychem certificate.
Tape wrapped with 1/3 overlap black and 1/3 overlap white.
Coal tar enamel field flood coated by experienced crew.
The whole pipeline was layed on a bed of sand and then back filled with a variety
selected materials to simulate many of the conditions experienced
in the field.
This section of the pipeline is layed and backfilled to the highest specifications found on cross-country pipelines thoughout the world.
These circumstances are found when weather conditions are good at the time of construction and there is an efficient team of trained pipeliners carrying out the work with no pressures to complete the job in a hurry.
There must be a plentiful supply of good quality sand that has not got a particularly high value on the local market.
The construction company would have had good quantity survey and inspection services in place.
grass and organic
This type of backfill is common when the pipeline crosses agricultural land during wet weather when everyone is fed up with the job and in a hurry to get home. It is very easy to persuade the backfill inspectors to go to the comfort of a local hotel bar and the dozer drivers to push whatever is available into the ditch on top of the pipe.
Pipelines often pass through urban areas that have been used as rubbish landfill sites in the past. The specification for backfill is usually very strict and the inspection usually good. However, in many cases there are lengths of pipeline that are backfilled with rubbish such as we have use in this section of the main pipeline. In such instances it is nearly impossible to take core samples to ascertain the pH of the electrolyte or establish the true nature of the backfill that can vary meter by meter.
Good arable top-soil is often in plentiful supply and used as backfill. This often
has better conductance than surrounding ground and will affect the path taken by the cathodic protection current and must be considered when interpreting the voltage measurements.
This grey sand has different qualities to the brown sand. The colour is the result of the differing chemical composition of any material and is a good indicator of that component of the corrosion configuration.
granite pieces and chips
The pipeline passes under concrete with no sleeve and under ashphalt with a sleeve.
The anulus between pipe and sleeve has spacers and no filler.
The sleeve has a vent and no coating.
An impressed current cathodic protection system is installed, and can be connected to all pipelines.
Sacrificial anode on main pipeline
The main pipeline has a sacrificial anode that can be switched to enable a hybrid system to be analysed.
The second pipeline is 12 M long and runs in a continuous wayleave from the main pipeline.
Sacrificial anode attached to second pipeline.
The third pipeline is a T off from the second but not connected. It crosses the first pipeline allowing for interference to be simulated and studied.
A variety of equipment allows the whole system to simulate most forms of interference and complications.
A physical electrical model is being made concurrent with the construction of the training centre.
This will reflect the measurements and readings obtained by a variety of techniques and procedures.
A computer model is being developed to simulated the whole training center layout
as an equivalent circuit enabling circuit analyses to be carried out using
standard electronic software if necessary.
Soil samples have been taken at selected locations.
A control panel is being constructed to display the training area and simulate the automatic control of a pipeline system.