For gas pipe, internal corrosion is the electrochemical response of recurring water and acid gas in the pipe comparable to galvanic cell and also the chain reaction that ruin the steel latticework. Both of these reactions create the pipe wall to loosen up, fall off and bore, which can no more endure the stress of natural gas in the pipe. In useful application, a sort of layer can not be very good protection, or can't satisfy the demand such as anti-corrosion, weather resistance, good look, as well as consequently most a number of covering on steel surface finishing interact to create a whole system, including guide layer, the middle layer, paint, layer one or numerous times each layer respectively as needed, and also there is only solitary layer such as powder finishes can satisfy the different needs at the same time.

The anti-corrosion coating of gas pipe should have the following homes: effective electric and also water insulation; Not restricted by layer approaches; Good attachment to pipeline surface; Resistant to harm throughout installation, storage space and transport; Resistance to chemical tool damage; Easy to repair; Long solution; Environmentally friendly as well as non-toxic. Today, the anti-corrosion layers for cross country transportation pipes mainly consist of coal tar paint, 2LPE, 3LPE, integrated epoxy powder (FBE), as well as double-layer integrated epoxy powder (FBE double-layer) finish.

Coal tar enamel.

Coal tar paint layer is the early pre-owned finishing, it's characterized by excellent insulation performance, low tide absorption, resistance to bacterial deterioration and also plant root penetration, long life span and low cost. However, its mechanical stamina is low and has a small suitable temperature level array, it might leave harmful gases as well as calls for stringent smoke treatment. In recent times, it has actually been gradually changed by various other covering layers due to the limitation of environmental management.

2LPE.

2LPE has great insulation efficiency, low water absorption, high mechanical stamina, tough wear resistance, acid, antacids, salt as well as bacterial deterioration, temperature modification resistance.

Nevertheless, there are also disadvantages: simple aging, inadequate attachment wldsteel.com with the steel tube surface, bad anti-cathodic removing efficiency. Electrostatic shielding of PE layer is not for external current cathodic protection.

3LPE.

The three layers of PE anti-corrosion layer combine the benefits of high density polyethylene and also merged epoxy powder. The epoxy powder is firmly combined with the surface area of the steel pipeline, as well as the high thickness polyethylene is immune to mechanical damages. The glue layer between the two layers makes the 3 type a composite structure of molecular bond, which realizes the good combination of deterioration resistance and mechanical buildings. It is the front runner for massive natural gas transportation pipe engineering.

Blend bonded epoxy powder (FBE).

The PBE finish has solid bonding with the surface area of the steel pipeline, excellent insulation performance, high mechanical strength, temperature change resistance and also chemical corrosion resistance, and also can be used in a selection of extreme atmospheres. The major disadvantage is bad ultraviolet resistance and also the thin 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, exactly how does the finish shield the internal wall of the gas pipe? We currently understand that metal corrosion is due to the activity of the ecological medium on the metal surface area to produce electrochemical response or chain reaction, the effect of the finish on the pipeline is attained by hindering the above reactions:.

( 1) Shielding: Many finishings on acid, antacids, salt and various other destructive media reveal chemical inertia, and also the high dielectric continuous to stop the development of rust circuit, so the metal surface finish to the metal surface area and also the atmosphere isolation as well as shielding the corrosive medium. It needs to be pointed out that the polymer layer is breathable and closely pertaining to its structure.

( 2) Passivation sluggish release: With the aid of antirust pigment in the covering as well as the metal surface area response, make it passivation or produce protective substances; In addition, several oils can also function as organic deterioration preventions by producing degradation items under the catalytic activity of metal soaps.

( 3) Electrochemical security: The covering potential is lower than iron metal filler (such as zinc) will certainly compromise the cathodic defense of the anode, and also the climatic deterioration products of zinc antacids zinc carbonate is fairly stable, can be closed, plug the final void.

So how to prevent the corrosion of the internal wall of the natural gas pipeline? We can stay clear of by doing this: firstly, the gas drawn out from the ground experiences a collection of processes such as desulphurization and also dehydration, prior to it enters the long-distance pipeline. Secondly, the reliable interior coating of the pipe can minimize rust, gas transmission resistance as well as cleaning time.