The environment is highly corrosive in the top section of fractionator in the crude oil distillation unit. SUS27 (18-8 steel) was failured due to stress corrosion cracking in 3 months and SUS38 ...(13Cr-Al steel) due to severe general corrosion. Corrosion resistance of typical austenitic and ferritic stainless steels and the developed 17Cr-Mo steel were compared in such an environment. Then, corrosion resistance of these steels in a few mineral acid solutions and of their weld joints were compared in laboratory. The results were as follows: (a) In the top section of fractionator, 17Cr-Mo steel (containing 0.5-2%Mo) is most resistant to general or pitting corrosion and/or stress corrosion cracking. (b) In laboratory tests, 17Cr-Mo steel shows the lowest corrosion rate in hydrochloric acid solution of 0.1% concentration or less. (c) Austenitic steel containing Mo also shows low corrosion rate in dilute hydrochloric acid solution, but it appears to be susceptible to stress corrosion cracking in dilute hydrochloric acid solution saturated with hydrogen sulfide, judging from test results with SUS27 (18-8). (d) Weld joint of 17Cr-Mo steel is resistant to corrosion as well as the base sheet or plate itself.
The susceptibilities of the stainless steels to stress corrosion cracking in hydrogen sulfide-saturated water were studied. The U-bended pieces of the austenitic steels cracked under the following ...proposed test conditions; dipping in the water prepared to pH 3.0 with hydrochloric or sulfuric acid and saturated with hydrogen sulfide, at 80°C, and for 5-15 days. The cracks were transgranular in the solution-treated austenitic steels, and intergranular in the sensitized ones. Only shallow pittings were observed on the surfaces of the annealed ferritic steels, but intergranular stress corrosion crackings were observed in the sensitized ones under the same conditions mentioned above. In a new ferritic stainless steel, no crack was observed no but only shallow pittings were observed in both annealed and sensitized pieces.
Treatment for Myeloma of the Spinal Lesions Sagara, Taka-aki; Akasaki, Koji; Kawatani, Yosuke ...
Orthopedics & Traumatology,
2012/09/25, Volume:
61, Issue:
3
Journal Article
Open access
We experienced eight cases of myeloma with spinal lesion from 2001. The patients consisted of five males and three females with mean age of 64 years (range: 35 to 78 years). Seven patients had ...multiple myeloma and a patient had solitary myeloma. Five patients were obliged to undergo operative therapy because of pain and muscle weakness of the lower extremity, but two patients did not recover from Frankel B grade. The prognosis of myeloma patients with vertebral lesions seems to be very difficult to predict. Cooperation between physicians and orthopedic surgeons will become increasingly important.
Ossification of the posterior longitudinal ligament (OPLL) of the upper thoracic spine occurs clinically less frequently than that of the cervical spine. However, thoracic OPLL causes severe ...myelopathy and surgical treatment becomes necessary. We experienced two cases of upper thoracic OPLL by anterior decompression using the total sternum spitting approach. Case 1: A 62-year-old female with OPLL of T2-3 underwent anterior decompression and fusion of T2-3 using total sternum splitting approach. Her myelopathy improved without critical complication. JOA score improved from four to eight points. Case 2: A 51-year-old female with OPLL of T1-3 underwent anterior decompression and fusion of T1-3 using total sternum splitting approach. Myelopathy improved without critical complication. JOA score improved from three to nine points. The surgical outcome of anterior decompression and fusion by total sternum splitting approach for upper thoracic OPLL was good. This approach has a low risk of the injury of the intra thoracic artery and is useful.
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