welcome to the GMB

Unfortunately, of the vases from this factory showing in my book, this one is absent, but a little information as follows: my feeling is possibly designed by either Asta Stromberg or Gunnar Nylund, some time around 1957 - 58. At least that's about as near as I can get for this code, since I don't have more precise information on manufacturing dates - other folk may have a more accurate idea.
As you can imagine, there have been mountains of books on Scandi glass over the past 20 odd years - some very comprehensive and expensive, others just general coffee table books and cheap.
Unfortunately, the company suffered a serious fire some years back - was then sold to Orrefors - and finally ceased in 1979 I think. Whether Orrefors maintained the earlier records of Strombergshyttan I don't know.
Plain undecorated vases carried the prefix code B, with obviously other codes for bowls and engraved pieces etc., and this very accentuated bevelling of the rim was a feature common to much of their clear glass work. Let's hope someone else has more detailed and specific information for you.
As for removing stains from the interior of vases, we must have spilled gallons of ink on this over the years - if you use the Board's search facility and type in related words or phrases, can guarantee you'll have enough to read till the end of the month.
Ref. 'Smoke & Ice - Scandinavian Glass 1930 - 2000' - Vigier & Pina - 2002.