Steel Pipes Offering High Tensile Strength

Offering endurance under both internal and external pressure as well as resilience against distortion and shock, high-tensile strength steel pipes are used in the construction of natural gas pipelines. Designed to withstand major earthquakes, steel pipes have exhibited their reliability most recently during the Miyagi Prefecture offshore and Niigata Prefecture Chuetsu earthquakes.

Technologies that Protect Pipes against Corrosion

Pipelines laid underground are protected by an external surface coating. In addition, cathodic protection achieved by the impressed current protection method is applied in response to such issues as galvanic corrosion. Recognized for its easy maintenance and operation, the impressed current protection method has proven extremely reliable in the control of corrosion of metal surfaces. This is particularly true for long-distance, large-scale pipelines. Under this method, the metal surface acts as a cathode for an electrochemical cell. Insoluble electrodes (which are used to corrode in place of the pipeline) are placed underground in contact with the surface to be protected and act as the anode of the electrochemical cell. Protected from the plight of natural corrosion, underground pipelines have a virtual permanent life span.

Monitoring System

The flow and pressure of natural gas channeled to LDCs and other users is monitored on a 24-hour basis utilizing communication satellite and other service lines. A monitoring center and individual supply stations are equipped with remote display units through which natural gas flows and pressure are centrally monitored and controlled. In the event of an emergency, flows are shutoff through remote operations. Emergency shutdown valves (ESDVs) are installed at major valve stations, LDCs and other user transfer points to enable gas to be shutoff in the event of an emergency by monitoring centers through remote operation. Other safety structures and systems in place to accommodate extraordinary circumstances include vent stacks installed at key valve stations for the safe release of gas into the atmosphere as and when required. In order to ensure the stable supply of natural gas to LDCs and other users, patrols regularly maintain and inspect the entire length of the pipeline. Every precaution is taken to secure safety. Pipelines are placed on an alert status in the event of such natural disasters as earthquakes and heavy rain. Security tags and sign posts are also employed as appropriate.