Natural gas transmission systems transport natural gas from a production facility to distribution systems and end users.
Natural gas distribution systems take gas from the point at which the transmission system delivers gas to the “city gate” station to various consumer points of supply. Transmission systems and distribution systems are generally constructed of either steel or plastic to specific standards. Transmission systems are operated at pressures upwards of 2000 kPa. Distribution systems can be operated at various pressures that are typically up to about 400 kPa, although higher pressures are sometimes used.
Liquefied Petroleum Gas (LPG) is supplied by bulk tanker or in cylinders to supply depots and consumer installations. When stored and supplied in containers, LPG is in liquid form. It is vaporised by withdrawal from the tank or cylinder.
While most LPG supplied in New Zealand is delivered in bulk form or in cylinders, there are some small LPG distribution systems in the South Island.
A supply of gas is deemed to be unsafe if it is at a pressure or has a characteristic that, in a properly functioning gas installation, results in a gas appliance becoming unsafe.
The regulations specify limits for accuracy of measurement of gas for revenue purposes.
Gas supply systems that supply or are intended to supply annual consumption greater than 10 TJ of gas per year are required to maintain an SMS from 4 May 2013.