For gas pipeline, internal corrosion is the electrochemical reaction of recurring water and acid gas in the pipeline comparable to galvanic cell and also the chemical reactions that damage the steel latticework. Both of these reactions cause the pipeline wall surface to loosen up, fall off and bore, which can no more hold up against the stress of gas in the pipe. In functional application, a kind of finishing can not be great security, or can't fulfill the demand such as anti-corrosion, weather resistance, good appearance, and also as a result most several finish on steel surface area coating interact to create an entire system, consisting of primer layer, the middle layer, paint, finishing one or several times each layer specifically as required, and there is just single layer such as powder finishes can satisfy the various demands at the same time.
The anti-corrosion finishing of gas pipeline must have the adhering to residential or commercial properties: reliable electrical and water insulation; Not restricted by covering methods; Good adhesion to pipeline surface area; Resistant to harm throughout installment, storage space and also transport; Resistance to chemical medium damage; Easy to repair; Long service; Environmentally pleasant as well as safe. At present, the anti-corrosion finishes for far away transport pipes generally include coal tar paint, 2LPE, 3LPE, fused epoxy powder (FBE), and double-layer fused epoxy powder (FBE double-layer) finish.
Coal tar enamel.
Coal tar paint finishing is the early used layer, it's defined by excellent insulation efficiency, low water absorption, resistance to bacterial deterioration and plant origin infiltration, lengthy life span as well as low price. Nevertheless, its mechanical toughness is low as well as has a tiny appropriate temperature variety, it might leave hazardous gases and also calls for rigorous smoke therapy. In the last few years, it has been gradually changed by various other covering layers because of the constraint of environmental management.
2LPE.
2LPE has excellent insulation efficiency, low water absorption, high mechanical toughness, challenging wear resistance, acid, antacids, salt and also microbial deterioration, temperature change resistance.
Nonetheless, there are also disadvantages: easy aging, bad attachment with the steel tube surface area, inadequate anti-cathodic removing performance. Electrostatic protecting of PE layer is not conducive to outside current cathodic defense.
3LPE.
The three layers of PE anti-corrosion layer combine the benefits of high thickness polyethylene and integrated epoxy powder. The epoxy powder is securely integrated with the surface of the steel pipe, and also the high density polyethylene is immune to mechanical damage. The sticky layer in between the two layers makes the 3 type a composite framework of molecular bond, which realizes the great combination of deterioration resistance as well as mechanical properties. It is the front runner for large gas transportation pipe engineering.
Fusion adhered epoxy powder (FBE).
The PBE covering has solid bonding with the surface of the steel pipe, excellent insulation performance, high mechanical stamina, temperature change resistance and also chemical rust resistance, as well as can WLDSTEEL INC. be made use of in a range of harsh environments. The major drawback is inadequate ultraviolet resistance as well as the slim overburden layer (0.35 ~ 0.50 mm). The double-layer FBE is similar to 3PE, with excellent compatibility, smooth surface area of the covering layer, which can avoid cathodic securing.
So, how does the finish secure the inner wall surface of the gas pipe? We already recognize that metal deterioration is because of the action of the ecological tool on the metal surface area to create electrochemical response or chemical reaction, the result of the coating on the pipeline is attained by hindering the above reactions:.
( 1) Shielding: Many coverings on acid, alkali, salt and also various other corrosive media reveal chemical inertia, as well as the high dielectric consistent to stop the formation of deterioration circuit, so the steel surface area layer to the steel surface and the atmosphere isolation as well as securing the destructive tool. It has to be mentioned that the polymer finish is breathable and carefully related to its framework.
( 2) Passivation slow-moving launch: With the aid of antirust pigment in the layer as well as the steel surface response, make it passivation or create safety substances; In addition, many oils can likewise function as organic rust preventions by producing deterioration items under the catalytic activity of metal soaps.
( 3) Electrochemical protection: The finishing possibility is lower than iron steel filler (such as zinc) will compromise the cathodic security of the anode, and the climatic deterioration items of zinc antacids zinc carbonate is reasonably stable, can be closed, plug the final gap.
So exactly how to avoid the rust of the inner wall of the natural gas pipeline? We can stay clear of by doing this: first of all, the gas drawn out from the ground experiences a collection of processes such as desulphurization and also dehydration, before it gets in the long-distance pipeline. Second of all, the effective internal layer of the pipeline can reduce corrosion, gas transmission resistance and also cleaning time.