347H Seamless pipe / Boiler Tube / Stainless Steel Pipe
TP347H (1cr19ni11nb) is a high carbon Cr Ni austenitic stainless steel containing niobium. Because it contains stabilizing element Nb, it has good resistance to intergranular corrosion and polysulfate intergranular stress corrosion. In acid, alkali, salt and other corrosive media, its corrosion resistance is similar to that of 18-8 austenitic stainless steel containing Ti. Therefore, it is widely used in boiler, power generation, petroleum, chemical industry, synthetic fiber, food, papermaking and other industries. Used for large boiler superheater tube, reheater tube, steam pipeline and petrochemical heat exchanger.
#AISI ASTM SA UNS34709 TP 347H Seamless Austenitic Alloy-Steel Boiler, Superheater,and Heat-Exchanger Pipe/ Tubes
Application:
Used for large boiler superheater tube, reheater tube, steam pipeline and petrochemical heat exchanger. The allowable oxidation resistance temperature for boiler tubes .
ASTM SA213 TP347H S34709 stainless steel seamless pipe high pressure boiler tube 347h stainless steel boiler tube 347h stainless steel heat exchange tube 07cr18ni11nb stainless steel tube 347h stainless steel fluid tube 347h stainless steel seamless tube for nuclear power station
S34709 high pressure boiler stainless steel tube is a stabilized austenitic stainless steel containing Nb, which has good intergranular corrosion resistance and good corrosion resistance in alkali, seawater and a variety of acid solutions.
347h impermeable steel has the highest high temperature strength among the conventional 18% CR series austenitic heat-resistant steels, but its resistance to steam oxidation and spalling is limited. Through special heat treatment and hot working, TP347H grain is refined to above ASTM grade 8, that is, TP347h fine-grained steel is obtained, which improves the steam oxidation resistance. At the same time, due to the improvement of solid solution strengthening effect, the creep strength is improved, which plays an important role in improving the stability of superheater tube and has been widely used in many ultra supercritical nuclear power units
In 347h stainless steel, because niobium can fix carbon and make carbon difficult to escape, its ability to resist intergranular corrosion is quite outstanding. Niobium has a strong affinity with carbon, nitrogen and oxygen, and is a strong carbide and nitride forming element. When the content is greater than 8 times of carbon content, niobium can fix almost all carbon in the steel, so that the steel has good oxidation resistance, and niobium can increase tempering stability, It has the function of secondary hardening and can also improve the creep performance of steel. Niobium also has the function of refining grain, improving the impact toughness of steel and reducing its brittle transition temperature, which can improve the strength without affecting the plasticity and toughness. It can prevent intergranular corrosion of steel by oxidizing medium. It also has certain heat resistance. It can bear small load below 850 ℃, and its performance is similar to that of 1Cr18Ni9Ti, but its coercivity is low. It is mainly used to manufacture industrial equipment such as petrochemical, synthetic fiber, food and papermaking. It can be used as heat-resistant materials, such as exhaust main pipe and branch pipe of aeroengine and gas pipeline of turbine compressor, As well as other parts working under small load and temperature not exceeding 850 ℃, they can also be used as welding cores for welding nickel chromium stainless steel, radioactive system pipes, nuclear power pipes and pipes for high-pressure chemical industrial equipment
AISI TP347H UNS S34709 Chemical Composition, %
| C | Mn | Si | P | S | Cr | Ni | Cu | Nb | Fe |
| 0.04-0.10 | 2.0 Max | 1.0 Max | 0.045 Max | 0.030 Max | 17.0-19.0 | 9.0-13.0 | 0.50 Max | 8C-1.1 | Balance |
In recent years, with the rapid development of thermal power stations, the demand for 347h stainless steel tubes in the utility boiler industry has increased sharply. The ASTM SA213 Or ASTM SA312 347H stainless steel seamless pipe developed by Chongqing world steel has a maximum outer diameter of 720mm and a wall thickness of 50mm. 347H stainless steel seamless tube has good intergranular corrosion resistance and high temperature corrosion resistance due to the stable chemical element NB, It is widely used in heat exchanger and boiler industry.
