The Estimation Of Service Life For Gas Pipe Network

This article gave a description of the actuality about gas pipes network which now in Shenzhen and the whole country. As time goes on ,the gas pipe network in Shenzhen is being aged and move into a period when accident occurred very ofen. Since the aging and eroding of network itself and destroying caused by all kinds of artificial factors, it leads that the accidents occurred frequently and has influence seriously on the normal function and environment around. The security of network give prominence to increasingly. So it's very necessary to make integration of estimation for the service life of gas pipe network. As conclusion which comes from venture grade system of U.S experts, such hydrocarbon pipe network which venture account is about 300 and belong to seriously dangerous. Aim at each segment of the pipe,the difference of the condition brings the difference of invalidation time and influence on the environment surroundings.The main factors which influence it's service life are four sides:first is the condition around just like the physical chemistry characteristic of the soil, soil electricity resistance, pH value, bacteria instance, mottle electricity,etc;second is the effects of antisepsis,because different kinds of antisepsis layer used to protect the underground pipe, the effects is decisive to service life of the pipe. Generally, antisepsis and cathedral protection are both used to get double safeguard to enhance the effects. The article compares the performance of the antisepsis layer which used very often,such as PVC adhesive tape, epoxy power, coal tar bitumen,etc.The third is material and it's quality of the pipe and manufacture factors.The last one is the pressure during the running of pipe.For estimate the using of underground pipeline, detecting is necessary.Person method(PS),DC pressure grads method(DCVG),"A" frame method are used for breakage detection of antisepsis layer; standard pipe /ground potential detection method,dense intermission potential detection method are used for detection the parameter of cathode protection;multipipe current method, current and potential method, frequency conversion- frequency choose method used for detection resistance ratio of the antisepsis and insulated layer.It is bring forward that current attenuation ratio could be used to grade the antisepsis layer in pipe detection when the current detection technique adopts in multipipe. The epoch of natural gas is very near in shenzhenjt has calculated in the article whether it could endure for the function pressure which has breakage somewhere. As you know from thearticle that the decrement of wall thickness has not influence the matrix metal very much.The data used in the article is according to the digger gas pipe which is mined over 8 years, the actual data is lacking for time longer or wall thickness decreased more.The suggestion is bring forward in the article that we should make detection not less on the wall thickness of the pipe which is being used over 10 years, but also on the welding line and matrix metal capability of the pipe,and running archives should establish for all the pipe underground so that the pipe system could be in control.