For natural gas pipeline, interior deterioration is the electrochemical reaction of residual water and acid gas in the pipeline comparable to galvanic cell and also the chemical reactions that ruin the metal lattice. Both of these reactions trigger the pipeline wall surface to loosen, diminish as well as perforate, which can no longer stand up to the stress of natural gas in the pipe. In functional application, a type of covering can not be very good defense, or can not fulfill the demand such as anti-corrosion, weather resistance, excellent appearance, and also as a result most a number of covering on metal surface finish collaborate to form an entire system, consisting of guide layer, the center layer, paint, coating one or a number of times each layer specifically as needed, and also there is only solitary layer such as powder layers can meet the different demands at the very same time.
The anti-corrosion finish of gas pipe must have the complying with properties: effective electric as well as water insulation; Not restricted by finishing approaches; Good adhesion to pipe surface area; Resistant to damage throughout installation, storage and also transport; Resistance to chemical medium damage; Easy to repair; Long solution; Environmentally friendly as well as safe. At present, the anti-corrosion coverings for cross country transportation pipes generally include coal tar paint, 2LPE, 3LPE, integrated epoxy powder (FBE), and double-layer integrated epoxy powder (FBE double-layer) finish.
Coal tar enamel.
Coal tar paint finish is the very early used covering, it's defined by excellent insulation efficiency, low water absorption, resistance to microbial rust and also plant root penetration, lengthy life span and also low cost. Nevertheless, its mechanical strength is reduced and also has a little suitable temperature variety, it might leave toxic gases as well as needs strict smoke therapy. In recent times, it has been progressively replaced by various other covering layers as a result of the restriction of environmental protection.
2LPE has excellent insulation performance, low tide absorption, high mechanical stamina, hard wear resistance, acid, antacids, salt and also bacterial corrosion, temperature level change resistance.
However, there are additionally disadvantages: very easy aging, inadequate adhesion with the steel tube surface, inadequate anti-cathodic removing efficiency. Electrostatic protecting of PE layer is not for outside current cathodic protection.
The 3 layers of PE anti-corrosion layer integrate the benefits of high density polyethylene as well as merged epoxy powder. The epoxy powder is securely combined with the surface area of the steel pipe, and also the high thickness polyethylene is immune to mechanical damages. The sticky layer between the two layers makes the 3 kind a composite framework of molecular bond, which understands the excellent combination of deterioration resistance as well as mechanical buildings. It is the front runner for large gas transport pipe design.
Blend bonded epoxy powder (FBE).
The PBE finish has strong bonding with the surface of the steel pipe, great insulation performance, high mechanical stamina, temperature adjustment resistance and also chemical deterioration resistance, and can be utilized in a variety of severe atmospheres. The primary negative aspect is inadequate ultraviolet resistance as well as the thin overburden layer (0.35 ~ 0.50 mm). The double-layer FBE resembles 3PE, with great compatibility, smooth surface area of the covering layer, which can prevent cathodic protecting.
So, exactly how does the finishing safeguard the inner wall of the gas pipeline? We already understand that metal rust is due to the activity of the environmental tool on the metal surface area to produce electrochemical reaction or chain reaction, the impact of the covering on the pipe is accomplished by inhibiting the above reactions:.
( 1) Shielding: Many coatings on acid, antacids, salt and various other harsh media reveal chemical inertia, as well as the high dielectric continuous to prevent the development of corrosion circuit, so the steel surface area finish to the steel surface and the environment isolation as well as securing the harsh medium. It should be explained that the polymer finish is breathable as well as very closely related to its structure.
( 2) Passivation slow release: With the help of antirust pigment in the covering and the metal surface area response, make it passivation or generate safety compounds; In addition, many oils can additionally work as natural rust inhibitors by creating deterioration products under wldsteel.com the catalytic action of metal soaps.
( 3) Electrochemical security: The covering potential is less than iron steel filler (such as zinc) will sacrifice the cathodic protection of the anode, as well as the atmospheric deterioration items of zinc antacids zinc carbonate is reasonably stable, can be shut, connect the final space.
So just how to prevent the deterioration of the inner wall surface of the natural gas pipeline? We can prevent by doing this: firstly, the gas extracted from the ground experiences a collection of processes such as desulphurization as well as dehydration, prior to it goes into the long-distance pipe. Second of all, the efficient internal covering of the pipeline can minimize corrosion, gas transmission resistance and also cleaning time.