管道示蹤線測試原理

Principle of pipeline tracing line test

銅包鋼是由鋼芯線和緊緊包裹在其周圍的銅層組成的金屬芯。外側為PE防腐層。銅起傳導微弱電信號的作用，鋼絲起支撐作用。銅芯線一般由內層銅芯線、中間層絕緣護套和外層保護套組成。銅包鋁由鋁芯線和將其緊緊包裹形成金屬芯的銅層組成，外層為PE防腐層。

Copper clad steel is a metal core composed of steel core wire and copper layer tightly wrapped around it. The outer side is PE anticorrosive coating. Copper plays the role of conducting weak electrical signals, and steel wire plays the role of support. Copper core wire is generally composed of inner copper core wire, intermediate insulating sheath and outer protective sheath. Copper clad aluminum is composed of aluminum core wire and copper layer tightly wrapped to form metal core, and the outer layer is PE anti-corrosion layer.

由于鋼制燃氣管道外層防腐層為塑料層或具有絕緣防腐性能的涂層，其結構類似于銅包鋼、銅芯線、銅包鋁和其他外層，它們也是具有絕緣和防腐性能的塑料層。.因此，我們采用兩個等效物，采用PCM管道電流衰減率法來測試示蹤線防腐層的平均絕緣質量。

As the outer anti-corrosion coating of steel gas pipeline is plastic layer or coating with insulation and anti-corrosion performance, its structure is similar to copper-clad steel, copper core wire, copper-clad aluminum and other outer layers, which are also plastic layers with insulation and anti-corrosion performance Therefore, we use two equivalents and PCM pipeline current decay rate method to test the average insulation quality of the anti-corrosion coating of the tracer line.

檢測原理是向示蹤線施加一定頻率的電流信號，電流從示蹤線傳到遠處會逐漸衰減。其衰減與示蹤線塑料層的絕緣電阻率有關。示蹤線塑料層的平均絕緣電阻率越高，電流衰減越慢，反之亦然。

The detection principle is to apply a certain frequency current signal to the tracer line, and the current will gradually decay when it is transmitted from the tracer line to a distance. Its attenuation is related to the insulation resistivity of the plastic layer of the tracer line. The higher the average insulation resistivity of the tracer line plastic layer, the slower the current attenuation, and vice versa.

管道示蹤線試驗方法

Test method for pipeline tracing line

為保證示蹤線的導電性、強度、耐腐蝕性和耐用性，一般建議選用截面積大于2.5mm的多股銅線，并盡量將示蹤線保持在鋪設時管的頂部。在分支處，應剝去導線接頭的絕緣層，將銅芯絞在一起數圈，然后在接頭處纏上絕緣膠帶，以保持良好的導電性。

In order to ensure the conductivity, strength, corrosion resistance and durability of the tracer wire, it is generally recommended to select multi strand copper wire with a cross-sectional area greater than 2.5mm, and try to keep the tracer wire at the top of the pipe when laying. At the branch, the insulation layer of the conductor joint shall be stripped, the copper core shall be twisted together for several turns, and then the joint shall be wrapped with insulating tape to maintain good conductivity.

示蹤線應留有一定的線頭余量，并避免線頭被泥土或雜物覆蓋。為了減少不能出地的示蹤線末端的接地電阻，需要在剝去絕緣層后，將裸露的芯線30cm處做好接地。措施，定向鉆孔鋪設的PE管道，應使用較強的導體，以免施工過程中被拉斷，導致無法檢測定位；當導體的直徑遠小于埋深，而忽略地面介質和空氣的介質變化時，示蹤線可視為均質介質中的無限長線。

A certain amount of thread end allowance shall be reserved for the tracing line, and the thread end shall not be covered by soil or sundries. In order to reduce the grounding resistance at the end of the tracer wire that cannot be grounded, it is necessary to ground the exposed core wire 30cm after stripping the insulation layer. Measures: for PE pipes laid by directional drilling, strong conductors shall be used to avoid being broken during construction, which will make it impossible to detect and locate; When the diameter of the conductor is much smaller than the buried depth and the medium change of the ground medium and air is ignored, the trace line can be regarded as an infinite line in homogeneous medium.

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