How to stop interior rust of natural gas pipeline ?

Author : Kimble Lehto | Published On : 06 Mar 2021

For gas pipeline, internal rust is the electrochemical reaction of residual water and acid gas in the pipe similar to galvanic cell and also the chemical reactions that ruin the metal lattice. Both of these reactions trigger the pipe wall surface to loosen up, diminish and pierce, which can no more endure the stress of gas in the pipe. In useful application, a sort of layer can not be very good defense, or can not satisfy the demand such as anti-corrosion, weather condition resistance, great look, and as a result most a number of layer on metal surface area finishing collaborate to develop a whole system, consisting of guide layer, the middle layer, paint, finish one or numerous times each layer specifically as required, and also there is just solitary layer such as powder finishes can meet the different needs at the same time.

The anti-corrosion coating of gas pipeline ought to have the adhering to buildings: efficient electric as well as water insulation; Not limited by layer techniques; Good adhesion to pipeline surface area; Resistant to harm during installation, storage as well as transport; Resistance to chemical tool damage; Easy to repair; Long service; Environmentally friendly as well as non-toxic. Today, the anti-corrosion coatings for cross country transport pipelines mostly include coal tar paint, 2LPE, 3LPE, integrated epoxy powder (FBE), and double-layer fused epoxy powder (FBE double-layer) layer.

Coal tar enamel.

Coal tar paint covering is the early used finish, it's characterized by excellent insulation performance, low tide absorption, resistance to bacterial deterioration and plant origin penetration, long service life and low cost. Nevertheless, its mechanical strength is reduced as well as has a little suitable temperature variety, it might leave poisonous gases and needs strict smoke therapy. In recent times, it has been progressively replaced by various other covering layers as a result of the constraint of environmental protection.


2LPE has great insulation performance, low water absorption, high mechanical stamina, difficult wear resistance, acid, antacids, salt and also bacterial corrosion, temperature level modification resistance.

However, there are additionally disadvantages: easy aging, bad attachment with the steel tube surface area, inadequate anti-cathodic stripping efficiency. Electrostatic shielding of PE layer is not conducive to outside existing cathodic defense.


The three layers of PE anti-corrosion layer integrate the benefits of high density polyethylene and also merged epoxy powder. The epoxy powder is strongly integrated with the surface area of the steel pipeline, and the high density polyethylene is immune to mechanical damages. The glue layer in between both layers makes the 3 type a composite framework of molecular bond, which realizes the good mix of deterioration resistance and also mechanical homes. It is the first choice for massive natural gas transportation pipeline design.

Combination adhered epoxy powder (FBE).

The PBE coating has strong bonding with the surface area of the steel pipe, good insulation performance, high mechanical toughness, temperature change resistance as well as chemical corrosion resistance, and also can be utilized in a selection of severe settings. The main drawback is poor ultraviolet resistance and also the slim overburden layer (0.35 ~ 0.50 mm). The double-layer FBE is similar to 3PE, with excellent compatibility, smooth surface of the covering layer, which can avoid cathodic protecting.

So, exactly how does the coating safeguard the internal wall of the gas pipe? We currently recognize that steel deterioration is due to the activity of the ecological medium on the steel surface area to generate electrochemical reaction or chain reaction, the effect of the coating on the pipeline is achieved by preventing the above responses:.

( 1) Shielding: Many layers on acid, antacids, salt as well as other harsh media show chemical inertia, and also the high dielectric consistent to stop the development of deterioration circuit, so the metal surface coating to the steel surface as well as the environment seclusion as well as protecting the harsh tool. It has to be mentioned that the polymer covering is breathable as well as carefully related to its structure.

( 2) Passivation slow release: With the aid of antirust pigment in the layer as well as the steel surface area response, make it passivation or create protective compounds; In enhancement, lots of oils can likewise act as natural rust inhibitors by generating destruction items under the catalytic activity of steel soaps.

( 3) Electrochemical defense: The covering potential is less than iron steel filler (such as zinc) will compromise the cathodic protection of the anode, and the climatic deterioration items of zinc antacids zinc carbonate is relatively steady, can be shut, connect the final void.

So exactly how to prevent the corrosion of the internal wall surface of the natural gas pipe? We can avoid by doing this: to start with, the gas extracted from the ground undergoes a series of processes such as desulphurization as well as dehydration, before it gets in the long-distance pipe. Secondly, the effective internal finishing of the pipeline can decrease corrosion, gas transmission resistance and cleansing time.