Pressure Testing

All hydrocarbon pipelines are tested to 125% of the licensed maximum operating pressure of the line being put into service. Most tests are done hydrostatically but air testing is preferable during winter because methanol must be added to water to reduce the freezing point. The mixture must then be properly disposed of or reused in other tests. Even during winter warmer months of the year, it is becoming environmentally unacceptable to discharge the test water, without treating it first, back to groundwater. Testing with air or nitrogen though, means that the gas can simply be vented to atmosphere.

For safety reasons, the test pressure never exceeds 90% of yield and the tests are conducted on pipelines that are not larger that 16" in diameter.

Pigging & Purging

Alberta Mobile Air has de-watered many pipelines where the pipeline elevation profile dictates use of higher pressure equipment for the dewatering portion of the program. For larger diameter pipelines, it is sometimes advantageous to use Alberta Mobile Air's equipment even if relief is not an issue because of the large volume units that we can readily deploy.

To repair a crude oil pipeline, it is necessary to purge the line free of the crude oil before any welding can proceed. Alberta Mobile Air has been involved in many purging operations involving air. In these cases the rude oil is separated from the air by a batch(s) of water with poly pigs encapsulating the water. Of course, if the client chooses to use site-generated nitrogen, there is no need to use the batch of water to separate the crude oil and nitrogen.

Drying

Air drying of pipelines is made simple with Alberta Mobile Air's three tower and two tower desiccant dryers. These dryers are capable of supplying 170m3/min and 26m3/min of combined -57 degrees C dew point air at atmospheric pressure. When combined with Alberta Mobile Air's mobile compression, the dry air will push the cleaning and drying pigs and absorb the remaining free water in the pipeline. We supply the pigging heads, pigs, and air string to complete the job.