Cause of pipe failure

Press, 3 September 1977, Page 6

Cause of pipe failure

PA Wellington Earth movement was responsible for the failure of the Maui natural gas pipeline north of New Plymouth in Julv, said the Minister of Mines (Mr Gair) yesterday. He had received all the reports he had called for and they confirmed that detailed investigation of the failed section, including the undamaged pipe cut from either side of the failure, had shown no corrosion or welding irregularities which would have caused a failure of the pipe. “Geological investigation, supported by engineering and surveying checks on the pipe and the ground surface subsequent to the pipeline's being returned to service, have shown that the area in the immediate neighbourhood of the failure is, in

fact, subject to ground-; creep, aggravated by thevery wet winter period,” Mr I Gair said. | “Steps will be taken to introduce expansion loops into < ; the pipeline to relieve the i (stresses introduced by this < ■ground creep.” In the longer term, a close 1 monitoring of the particular section would be made to i ensure that the expansion loops would be sufficient ; safeguard or. alternatively, i ■to enable a decision to be ■ reached as to whether the < pipeline should be rerouted Mr Gair denied sugges- . tions that pipeline inspection ; •had not been adequate. The requirements of the i Petroleum Pipeline Regu- i ■ations demanded a con- ; i t i n u e d inspection by i qualified staff employed by a j pipeline owner, and in this (case the Natural Gas Corpor- i

ation had adequately fulfilled its obligations under the legislation. The petroleum pipelines inspectorate had continuously checked that inspections had been carried out, and the chief inspector was satisfied that this check had also been adequate. “After the failure, the methods of inspection and the frequency of inspection are being reviewed and even more detailed inspection will, in future, be carried out," said Mr Gair. "Although the repair of the failed section was completed as quickly as could be expected under the circumstances, some improvement in the emergency procedures and the equipment available may be required, and the corporation is considering the best ways to achieve such improvement.”