Steel Piping Tubing Materials in Paper Industry

Duplex stainless steel has been used in foreign pulp and paper industry for 30 years, and it is also one of the fields with the most use of duplex stainless steel. Nordic paper industry developed, at present almost pulp and paper pressure vessels are made of duplex stainless steel. Pori factory in Finland has produced more than 100 pressure vessels. The largest digester has a volume of 400m3. 

Most are made of 2205 steel, while others such as UR47N(00CR25Ni6.5MO3N), UR52N+(00Cr25Ni6, 5Mo3, 5CuN) and super duplex stainless steel have been used. To manufacture wood chip pre-steam, intermittent and continuous pulp pulpers, paper pressure roller and recycling equipment, etc., have achieved good results.

In the continuous sulfuric acid cooking device, the Cr of wood chip presteam is up to 8000ppm, 316L steel can only be used for 1 year, and UR47N can be used for 4 years without corrosion. Continuous digester corrosion is lighter than intermittent digester, often use 304L or 316L composite plate, in recent years due to wear corrosion, stress corrosion increase, replaced with 2205 steel, mainly used in the lower part of the digester.

The boiling liquid medium in the intermittent boiler is composed of Na2S, Na2SO4, Na2C03, NaCI and 20%NaOH. There are several in the world at present. By UR45N | Taiwan (2205) and UR47N composite steel plate or the whole board manufacturing batch digester in use, life expectancy in 10 years.

Typical medium conditions for chlorine dioxide bleach tanks are ph6-7, 70C, >600ppmCI", 300ppmCIO3" and 20200ppmCIO2. In this medium UR45N(SAF 2205) is better than 316L steel, but there is still pitting corrosion, it is best to use super duplex stainless steel UR52N+, SAF 2507, etc., can be beautiful with austenitic stainless steel containing 6%Mo phase.

In the field of pulp and paper industry, the domestic is almost blank, sulfate cooking method is still mostly made of low carbon steel cooking pot, and the use of dual-phase stainless steel has been widely used abroad

Cooking, bleaching and other equipment, domestic also introduced, but the number is very few. To sum up, it can be seen that the use of duplex stainless steel in China has certain limitations, such as a large number of foreign use of duplex stainless steel such as pulp and paper industry, oil and gas T industry, transportation, and even the construction industry several big fields we are not involved, some are just beginning. According to the national conditions, using the performance advantages of duplex stainless steel, in addition to continue to expand the application in chemical and petrochemical fields, combined with the pulp and paper industry technical transformation needs.

To develop applications in this field, as for oil and gas pipelines, it is difficult to promote the current price of duplex stainless steel is too high but the manufacture of chlorine ions and sulfur resistance required for oil and gas fields

Hydrogenation devices such as gas collection lines and heat exchangers can still use duplex stainless steel, even super duplex stainless steel. The development of Marine transport industry, chemical ship manufacturing side.