Rust is just one of the major reasons for the damages as well as failing of buried pipes. For the long-distance pipeline as well as central pipeline network of gas transmission, the rust of hidden pipes can not be directly found and is troublesome for maintenance. Exactly how to prevent corrosion damages is a vital variable of pipe security engineering. According to the deterioration part, the deterioration of hidden carbon steel pipe can be split into inner rust as well as exterior deterioration.

direct interment steel pipeline

Internal Rust

The interior rust of pipeline is triggered by corrosive chemical parts in the transported medium. Different tool cause different deterioration factors. As an example, natural gas is high in H2S, CARBON DIOXIDE, water material and dust, which may result in perforation as well as burst accidents. The interior deterioration of pipeline is not just the outcome of several outside elements, however also related to pipe product as well as production method, along with stress and anxiety.

External Deterioration

Dirt erosion. Soil is basically a porous gelatinlike blood vessel with 3 phase states: solid, liquid and also gas. The pores of the soil are filled with air and water. A certain amount of salt in the water makes the soil have ionic conductivity. The physical and chemical residential properties of the dirt and the electrochemical inhomogeneity of the steel material satisfy the electrochemical rust conditions of hidden pipes, resulting in corrosion.

Stray present rust. Stray current is the existing that wears away and harms steel pipelines outside of the protection system layout for underground flow. Roaming present corrosion includes DC stray present rust as well as ac stray existing rust. The DC roaming existing mostly originates from the dc electrified railway, the DC electrolytic tools basing electrode, the anode ground bed in the cathodic security system and more. The roaming current circulation process forms 2 deterioration batteries established by the external prospective difference. One is that the existing spurts of the rail and also right into the steel pipe. The rail is the anode of the deterioration battery, and also deterioration occurs. The other is the current draining of the pipe back to the rail, the pipe is the anode that rusts the battery, wears away, the rail is the cathode, does not wear away.

Casing rust. Via casing is commonly used in long-distance transport pipes. The rust of the casing (specifically the steel casing) through the pipe area is complicated and has a shielding impact on standard cathodic protection. Casing corrosion can be divided into conventional deterioration as well as unusual deterioration 。.

Erosion rust. As a result of the disintegration and also cutting of the riverbed by the river, the underwater bare pipelines are exposed in the river, resulting in erosion corrosion.

The Corrosion Tests Of Direct Interment Steel Pipeline.

Interior deterioration discovery.

Interior examination primarily includes the geometry of the internal wall surface of the pipeline (such as ellipticity, flexing, girth weld, rust decrease of wall thickness, etc.). Pipe c orrosion is generally identified by thinning of the pipe wall and local pits and pitting. General pipe corrosion discovery is primarily to gauge and also assess the modifications in the term of pipe wall. The inner deterioration of intricate liquid pipelines is closely related to the corrosion qualities of the medium as well as the circulation characteristics of the fluid.

Exterior corrosion discovery.

Buried carbon steel pipe outside rust security is generally composite layer made by insulating layer and cathode security. Cathodic protection criteria can be from the damages of the pipe defense WldSteel layer, judge the pipe deterioration. Established on the basis of the principle of this method, the examination parameters are primarily tube/potential dimension and dimension of tube existing.

Now there are 6 main sort of detection approaches for external cover: Pearson detection technique, alternating current depletion technique, dc possible slope approach (DCVG), in-tube existing and also voltage technique (likewise called dc present and voltage method), variance-frequency selection approach, as well as close interval potential approach (CIPS).

Amongst them, the first 3 methods are generally used to identify the damages factor of the outer cover; The center 2 approaches are mainly used to find the insulation resistance of the outer covering layer. The last method indirectly examines the problem of the outer covering layer by detecting the pipe protection possibility. These methods identify the condition of the outer finishing by applying ranked ac/dc power to the pipeline, or by means of the unfavorable protection of the pipeline, and also by finding signal modifications straight over the pipe.