In
316 stainless steel tube welding process we should distinguish between the bottom of the bow coating, choose to use their own welding materials for welding. In order to ensure the corrosion resistance of the coating, the weld composition of the coating should be as same as the coating steel composition, but at the boundary between the two layers, the coating must be diluted by the bottom layer to reduce or embrittle the corrosion resistance; while the bottom layer It is alloyed and becomes brittle. Therefore, the key to welding stainless steel plate is to deal with the welding of two parts of the border. The approach is to deal with the transition weld between the bottom and the cladding.
Post-weld heat treatment welded components of large-thickness stainless steel wrenches post-weld heat treatment eliminate residual stresses in the weld. However, it should be noted that when heat treatment temperature high, on the side of the carbon steel will form the decalcification of the ferrite body to reduce the progress; while the stainless steel side is carburized and become hard and brittle, forming impact toughness decreases, into a welded joint, the danger of failure is not desirable.
Detailed application of austenitic stainless steel tube in petroleum refining industry:
With petroleum refinery off gas, natural gas or naphtha as raw materials, after a series of chemical reactions can be made of ethylene, propylene, B fast, further synthesis can consume polyethylene, polystyrene, acetone, butadiene and so on. About the synthesis process is similar to the chemical industry, will be exposed to all kinds of acidic media, decommissioning corrosive quite harsh, and media conditions vary greatly, the scope of the information used is also wider, hit the stainless steel, nickel-iron-based resistance erosion of alloys and nickel-based corrosion resistant alloy.
(1) Ethylene consumption
The thermal synthesis furnace tube for ethylene consumption is mainly made of 0Cr25Ni20 or high-carbon 25Cr-20Ni (HK40) centrifugal cast pipe, making it the choice of high temperature and high creep rupture strength. Pipeline using Incolog800 alloy. Cryogenic steel is used at low temperatures and 0Cr18Ni9 is only used at -100 to -175 ° C.
(2) Acetylene
Acetylene consumption, due to thermal synthesis temperature above 1100 ℃, so the use of alloy grades higher than ethylene consumption grades.
(3) Other processing
Other processing, including oxidation, hydration, dehydrogenation, dehydration, alkylation, heterogenous and so on. It will be exposed to acid-related media process, the use of information is mainly 0Cr17Ni14Mo2 and 00Cr17Ni14Mo2, Inconel600, Incoloy800, 20 alloy and Hastelloy B, C, D and so on. The working conditions of these processes are shown in the following table. In the process of petrochemical industry, some processes need to use sulfuric acid, hydrofluoric acid, phosphoric acid, hydrochloric acid and other corrosive media, depending on the acid concentration, temperature and the use of different corrosion-resistant materials.
