Titanium sponge production process often used stainless steel tube cooler for cooling four titanium tetrachloride, and four titanium tetrachloride contact material for austenitic stainless steel (1Cr18Ni9Ti), and the cooling medium contact material for Q235A steel. The hot side of the casing pipe cooler is welded by 180 degrees stainless steel elbow.
In the production process, the casing pipe cooler is often blocked. When removing the cleaning and dredging, it is found that there are many cracks in the inner side of the inner edge of the stainless steel elbow.
Causes of cracking:
1, residual stress: stainless steel elbow residual stress is not eliminated, stress in addition to the working stress generated by the load, the residual stress is more from the manufacturing process. Under the action of internal pressure and thermal stress and welding residual stress, the casing tube heat exchanger will have a certain level of tensile stress condition.
2, corrosion environment: in the casing for titanium tetrachloride liquid heat exchanger pipeline, the major media, which also contains ferric chloride, sodium chloride. Due to the double pipe heat exchanger without blowing and discharging device, in the long term parking cause into the air and water droplets, lead to pipeline gathered in the hydrolysis of titanium tetrachloride and blockage of the pipeline, the lower and because chloride containing chloride ions of the material corrosion resistance, led to the acceleration of corrosion.
3, material: tube plate’s pipe material for the 1Cr18Ni9Ti, in the chloride environment is easy to produce stress corrosion, and generally wear crystal fracture.
Control measures:
1, the choice of high stress corrosion material: in recent years for the development of a variety of should endure the stress corrosion of stainless steel: high purity austenitic chromium nickel steel, high silicon austenitic chromium nickel steel, high chromium iron prime steel and iron ferrite – austenite dual phase steel. Among them, the resistance to stress corrosion resistance of ferrite austenite dual phase steel is the best.
2, the control of stress: by stabilization after solid solution treatment can eliminate stress, also can obviously improve the material resistance to chloride cracking performance, but consider adopting this method to eliminate the stress should be a good trade-off by sensitization may cause all sorts of problems.
3, strictly comply with the operating procedures: process operation, process conditions on the corrosion of austenitic stainless steel has a huge impact. Therefore, it is necessary to strictly control the media composition, flow rate, temperature, pressure, pH value and other technical indicators. Adding corrosion inhibitor to the range of process conditions.
4, maintenance and management: to ensure the long-term safe operation of the heat exchanger casing type heat exchanger should be strict implementation of regulations and laws and regulations related to heat exchanger, the defects must be reexamined, timely grasp the operation of defects in the development of the situation, take appropriate measures, reduce equipment corrosion.
Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)
Tuesday, January 4, 2022
Reasons for cracking of austenitic stainless steel elbow
Related Posts:
What is threaded flange?What is threaded flange?A threaded flange is a connecting device that can be secured to a length of pipe without welding. Using a tapered thread, the … Read More
When to use slip-on flanges vs. lap joint flangesCurrently we are using lap-joint flanges and welding them directly to the piping. Is this an appropriate way to use lapped flanges, or should I chang… Read More
Outdoor water supply stainless steel pipe fittingsOutdoor water supply stainless steel pipe fittings, when the rain period construction should dig drainage groove, collecting well, ready to pump (subm… Read More
Surveying and mapping method for 180 degree stainless steel pipe fittings180 degree stainless steel pipe fittings mapping method are as follows:(1) with wire or the level of Surveying and mapping at both ends of the flange… Read More
What are lap joint flanges?What are lap joint flanges?Lap Joint Flanges (LJ Flanges) or Loose flanges (LF flanges) called are used on piping fitted with lapped pipe or with lap … Read More
0 comments:
Post a Comment