There is indeed not much readily available about W B Haas & Co. I can tell you a little bit, however, that might provide some useful context for your pipe.
The firm originated in St Claude, Jura, France as W B Haas et Cie; as you probably know St Claude was the epicenter of briar pipe making for the second half of the 19th century (the focus moved to England as the 20th century wore on, but that's another story).
Haas was in business in France no later than 1883, and by 1891 a UK affiliate was listed in the London directory as W B Haas & Co. Ltd., located at 6 Castle St, Falcon Sq, EC. There it remained at least through 1899, after which its appearance in directories becomes more sporadic. About 1905 the address is listed as 23 & 25 Bevendon St., East Road, N. Shortly thereafter it appears in neither city nor early telephone directories.
Several notices make it clear that the company (described as "well known pipe manufacturers") was doing business in Australia (and presumably New Zealand) by 1891.
The Aluma name was trademarked in the UK in the first week of February in 1894. It appears in industry trade directories of "pipe, pouches, fancy goods, etc" through 1934, and is absent in 1936.
There is a hint that W B Haas may have been absorbed by A. Oppenheimer (both are listed as producing pipes using the brand name Riseagle), but the evidence I've seen so far is too slender to feel confident. Certainly their profile, never terribly high, recedes into the mist early in the 20th century.
So to sum, the evidence is consistent with a pipe dating from 1894 onward. Personally I find Jesse's view that it dates earlier rather that later persuasive. At a pinch I'd think 1894-1904 not a bad provisional range.