Pipeline corrosion reasons: 1, poor construction quality coating; 2, soil properties through lots of different pipes, easy to form an oxygen concentration cell, so that part of the pipe section appear localized corrosion; 3, anti-corrosion layer mending failure, a serious impact antiseptic quality; 4, anti-corrosion materials, poor resistance to aging; 5, cathodic protection rate is less than 100%. The proportion of accidents caused by violation of rules for third place.

Pipeline external damage mainly refers to the role of external forces to make the pipeline or equipment from damage. Such incidents accounted for 8.3% of the total number of accidents, the reason is as follows: 1, force of nature disturbs the pipeline deformation or rupture; 2, pipeline workers artificially make piping or equipment damage; 3, non-pipeline sabotage the pipeline workers or equipment. Pipeline point multi-line long, mostly buried in the ground, if the problem is not the quality of construction of buried money to solve, it will leave to run in the future pipeline accidents. Once a long-distance pipeline leak detection and repair more difficult and expensive. So, how good construction quality is the key to the safe operation of the pipeline.

Main problems of construction quality are the following several aspects: 1, nozzle weld quality problems; 2, trenching, down pipe, backfilling, construction procedures were not strictly in accordance with that pipe coating before running it destroyed. 15 accidents caused by pipe quality, the spiral weld cracking 10 cases, one case of leakage defects caused blisters. China's manufacturing mostly ssaw steel pipe, spiral pipe joints have their own little bit, but it has a stress concentration weld length, weld defects caused by the accident and thus higher than the probability of straight pipe joints. Even straight seam steel pipe, weld inspection if failed, will leave accidents.