BS 3603, 1503, 1501 1

[Mountain2000]

I am Looking for the ISO, EN, ASME or DIN equivalent of the following steel: BS 3603 COS27 LT50
The writing on the drawing from 1975 is awful, so it might be something similar like:
BS 3603 CDS27 LT50
BS 3603 C0S27 LT50
BS 3603 CAS27 LT50
It should be some material for tubes.
The other - almost unreadable - item is BS1503 224 Gr.28A LT 50, which would be some carbon steel for plates. It couls be an error, becaus the Item BS1501 224 Gr.28A LT 50 is used too, but probably the forging variant. Any thoughts?

Thanks

 

[TVP]

The designation is BS 3603 CDS27 LT50. The contemporary designations for low-temperature, pressure-capable tubes are P215NL (1.0451) or P265NL (1.0453) in EN 10216-4 or ASTM A333 Grade 6. Here are some references:

http://www.smp-tubes.com/img/Downloads_Prospekte_2011/SMP_Heat_Exchanger_Tubes.pdf

http://www.vmexport.be/vme/pdf/din.pdf

http://www.tubesolution.com/standard/BS/BS 3603.pdf