Maybe part of an inscription along the lines of "---thorn Crucible Steel Foundry Company".
Various small foundries that cast steel as well as the usual iron used crucibles rather than larger and more expensive plant (open-hearth furnaces, tropenas converters, etc) to melt steel, and hence described themselves as "crucible steel foundries". For example. its still possible to see some manhole covers in the Cynon Valley inscribed "Hirwaun Crucible Steel" (or similar wording - this is from memory).
The challenge will be to identify the missing letters before "thorn". As these smaller castings often didn't sell too far outside their county of origin, it might be worth scanning early twentieth century trade directories from the Noirth Riding and from adjoining counties.