Introduction of welding materials for flue gas desulfurization project

2022-07-14

Under the development of the international trading and shipping transportation, the pollution caused by exhaust emission of ships fueled with petroleumis becoming more and more serious,especially after the emission of SO₂, the oxidation process of SO₂ in the atmosphere combines with the water mist in the cloud to form acid rain.

Now, the main methods to reduce SO₂ emission are as follows:

Using low sulfur fuels

Petroleum desulfurization

Flue gas desulfurization,

The flue gas desulfurization technology is widely used to control the emission of SO_X.

In responding the call, starting from 2020 the sulfur emission requirement of all marine heavy fuel in the world should be reduced to 0.5%,therefore the desulfurization tower must be added to all ship types.

The flue gas desulfurization device is generally divided into upper and lower parts,

The temperature of the upper part is lower, the material used are super duplex stainless steel S32750,

The temperature of the lower part is higher, the material are all austenitic stainless steel s31254

1. The S32750 in the upper part belongs to super duplex stainless steel,he main components are Mo, Cr, Ni and a certain amount of n (the alloy content is higher than S31803),The pitting resistance index PREN is greater than 40, the alloy composition is higher than other ordinary duplex stainless steel, it has better corrosion resistance and high strength.

For S32750 welding, select the welding wire with matching composition, the GTS-2594 (AWS a5.9 er2594) and GES-2594 (AWS a5.4 e2594-16), the deposited metal has excellent properties, and through intergranular corrosion, pitting corrosion and other corrosion tests.

2. The S31254 in the lower part belongs to high chromium and high molybdenum stainless steel, it has excellent corrosion resistance, it is mainly used in seawater and other environments containing halides, it has excellent pitting resistance, and because its structure is single phase austenite, extremely sensitive to welding hot cracks, therefore, welding materials with low S and P should be selected.

3. For the welding of S31254, using the matching welding wire, the GTN-CM3 (AWS a5.14 ERNiCrMo-3) and GEN-CM3 (AWS a5.11 enicrmo-3), the GTN-CM3is using for backing and GEN-CM3 for filling and capping,these are common welding processes, these kind of welding material has good crack resistance, and it can obtain better welding process performance.

Whether it is LNG ship, dual fuel ship, EFI engine or ship exhaust gas treatment, the global shipping, the ship owners, ship managers and the crews will be facing a change, adapting to the changes of the market is the only way.

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