Wasif,
There is no direct way to find the ASTM equivalent. First find the UNS number for OLT 35. Looks like STAS is a Romanian standard. Once you know the UNS no. You can look up the ASTM equivalent in many reference charts. Matweb is one place. ASME BPVC Sec II Part D is another. ASME B31.3 Table A-1 is another.
Thanks. In Romanian Standard, STAS 8183-80, is there any difference between tube and pipe material and dimensions? . As in ASTM standard Schedule is used for pipe and there is standard chart for pipe dimension , further tube dimension is given in guage. In Romanian standard, is there any difference in tube and pipe dimensions and material.
M.Wasif,
I am not sure about your project but remember to look at two things when you plan to replace the Romanian tubes with ASTM tubes. One is obviously, the material equivalence, the other is the dimensional standard. While the ASTM material will follow the ASME B36.10, the Romanian tube might follow one of the dimensional standards like STN 42 6710, 42 5716 or 42 5715.
Romanian mills are very versatile. They make pipe & tubes for European, Russian and North American markets
I personally have no experience with Romanian material. This is what I found doing some research.