For natural gas pipeline, interior deterioration is the electrochemical reaction of recurring water and acid gas in the pipeline similar to galvanic cell and the chemical reactions that ruin the metal latticework. Both of these responses trigger the pipeline wall surface to loosen, fall off and also bore, which can no longer stand up to the pressure of natural gas in the pipe. In functional application, a sort of finish can not be excellent protection, or can not fulfill the need such as anti-corrosion, climate resistance, good look, and also consequently most numerous layer on metal surface finishing collaborate to develop an entire system, including primer layer, the middle layer, paint, layer one or numerous times each layer specifically as needed, as well as there is just solitary layer such as powder coatings can fulfill the different needs at the very same time.
The anti-corrosion layer of natural gas pipeline ought to have the complying with homes: efficient electric and water insulation; Not restricted by finish approaches; Good bond to pipe surface area; Resistant to damage throughout installation, storage space and transportation; Resistance to chemical medium damages; Easy to fix; Long solution; Environmentally friendly and non-toxic. Currently, the anti-corrosion layers for cross country transport pipelines generally include coal tar paint, 2LPE, 3LPE, integrated epoxy powder (FBE), and also double-layer fused epoxy powder (FBE double-layer) layer.
Coal tar enamel.
Coal tar paint layer is the early secondhand covering, it's identified by good insulation performance, low tide absorption, resistance to bacterial deterioration as well as plant origin penetration, long life span as well as low price. Nevertheless, its mechanical stamina is reduced and also has a little ideal temperature level array, it may escape hazardous gases as well as requires strict smoke therapy. In the last few years, it has actually been progressively changed by other covering layers as a result of the constraint of environmental protection.
2LPE.
2LPE has excellent insulation efficiency, low tide absorption, high mechanical stamina, difficult wear resistance, acid, antacids, salt and microbial deterioration, temperature modification resistance.
Nonetheless, there are additionally disadvantages: very easy aging, poor adhesion with the steel tube surface area, inadequate anti-cathodic stripping performance. Electrostatic shielding of PE layer is not for external current cathodic protection.
3LPE.
The three layers of PE anti-corrosion layer incorporate the benefits of high density polyethylene and integrated epoxy powder. The epoxy powder is strongly integrated with the surface area of the steel pipe, and the high thickness polyethylene is resistant to mechanical damages. The sticky layer between the two layers makes the 3 kind a composite structure of molecular bond, which realizes the great mix of corrosion resistance as well as mechanical residential or commercial properties. It is the first choice for massive natural gas transport pipeline design.
Combination adhered epoxy powder (FBE).
The PBE finishing has solid bonding with the surface area of the steel pipe, good insulation performance, high mechanical stamina, temperature adjustment resistance as well as chemical deterioration resistance, and also can be utilized in a selection of harsh environments. The main downside is inadequate ultraviolet resistance and also the slim overburden layer (0.35 ~ 0.50 mm). The double-layer FBE resembles 3PE, with good compatibility, smooth surface of the covering layer, which can stay clear of cathodic shielding.
So, exactly how does the covering shield the internal wall surface of the gas pipe? We already recognize that metal corrosion results from the activity of the ecological medium on the metal surface to generate electrochemical reaction or chain reaction, the effect of the finish on the pipe is attained by inhibiting the above responses:.
( 1) Shielding: Many finishes on acid, antacids, salt as well as various other corrosive media reveal chemical inertia, and also the high dielectric constant to avoid the development of corrosion circuit, so the metal surface area coating to the metal surface area and also the setting seclusion and also securing the corrosive tool. It has to be mentioned that the polymer covering is breathable as well as very closely related to its structure.
( 2) Passivation slow launch: With the aid of antirust pigment in the coating as well as the steel surface area reaction, make it passivation or produce protective compounds; In enhancement, several oils can likewise act as organic deterioration inhibitors by creating destruction products under the catalytic action of steel soaps.
( 3) Electrochemical protection: The finish possibility is less than iron metal filler (such as zinc) will certainly give up the cathodic defense of the anode, and Read More Here the atmospheric deterioration items of zinc alkali zinc carbonate is relatively steady, can be shut, plug the last space.
So just how to prevent the deterioration of the internal wall surface of the natural gas pipe? We can prevent by doing this: firstly, the gas removed from the ground goes through a collection of processes such as desulphurization and dehydration, prior to it enters the long-distance pipe. Secondly, the effective internal coating of the pipeline can minimize deterioration, gas transmission resistance and cleaning time.
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