The 813 mm diameter, X70 grade MoDa Pipeline, which runs between China and Russia, is a spur line of the East Siberian Oil Pipeline system. Covering a total distance of 926 km, the pipeline extends from the Chinese city of Mohe near the Russian border to Daqing, an important oil and petroleum producing city in China’s northeast.

The pipeline crosses arctic tundra and boreal forests, which presented the engineering parties with unique and challenging circumstances. The remote location of the pipeline also meant that the mobilisation of skilled workers, equipment and materials to site was challenging.

Withstanding extreme circumstances

The Chinese government enforces stringent rules with the aim of protecting its natural resources. The MoDa Pipeline runs through an important natural forest in northeastern China.

To mitigate the risk of forest fires, the government insisted that the construction works on the project be carried out during the winter season. This meant that the joint field coatings to be applied to the repaired section of pipeline would not only have to be resistant to a temperature of -25 degrees Celsius, but also applied in such conditions. This made the option of using traditional shrink sleeves difficult, as the shrink sleeves need to be heated to perfectly fit around the joint and can only be applied in minimum ambient temperatures of -5 degrees Celsius or higher.

In addition, the extremely low temperature of the region can cause the temperature inside the pipeline to drop to a level that may affect operational efficiency. In total, 180 km of the pipeline need to be thermally insulated to ensure appropriate functioning conditions for the pipeline.

These requirements meant that a high-quality coating had to be used, and with temperatures that could fall as low as -30 degrees Celsius, traditional insulation and protection methods would not be suitable to execute this project.

The existing MoDa Pipeline had been factory coated with three-layer polyethylene (PE), which was not providing sufficient protection against the harsh snow and frost. PE coating is crystalline, which means it will rupture when temperatures drop below -20 degrees Celsius. The selection of repair works to be carried out was determined by the specific limitations of this product.

China National Petroleum Corporation and the Daqing Oilfield Construction Group teamed up with STOPAQ to provide a coating solution to meet the specific requirements of the project. Several simulations were developed, in which STOPAQ’s experience with previous projects proved to be valuable.

The coating solution

STOPAQ was able to design coating solutions for the 180 km insulated section of the pipeline as well as the remaining length. For the 180 km pipeline section, STOPAQ wrapping band is covered with polypropylene (PP) outer wrap. For the remaining segments, STOPAQ’s wrapping band and paste are sufficient to protect the factory-applied coating from further cracking.

Coating commenced in May 2009, and is expected to be completed in November 2010. In total, 36 coating employees have worked on the project. Under normal circumstances, it takes an average of 8 minutes to cover an entire pipe joint with STOPAQ’s wrapping band. While working on the MoDa Pipeline, coating teams have reached a maximum of 20 joints per day. In total, more than 24,300joints will be coated using STOPAQ wrapping band for corrosion prevention purposes.

STOPAQ has a guaranteed lifespan of 30 years. Its service life exceeds 60 years.

Coating projects in the pipeline

Other projects in which STOPAQ’s protective technology will be applied include the Zhong – Mian Line running from Myanmar to China, the 900 km Shan – Jing line between Yulin and Beijing, and the 1,600 km Zhong-Gui line from Zhonwei to Guiyang.

At the time of writing, STOPAQ was tendering for the coating repair contract for the 9,012 km West – East Pipeline. This six year old pipeline needs to have its field joints repaired, which were initially covered with shrink sleeves.