Distribution catalogues have a particular origin that still shapes them. They were digitised from printed price lists, and a printed price list is an ordering instrument: it assumes the reader has already decided and needs the code. Search by part number works beautifully because that is the job the structure was built for.
The buyer who has not decided is doing something else entirely. They have a specification to meet, and they are trying to find every part in your range that meets it.
Eleven parts fit and the site can show you all eleven
An engineer needs a valve rated to a pressure, in a thread size. Your catalogue contains eleven that qualify. The website can list them, ordered by part number, and it cannot filter by either of the two properties that decide the purchase.
So they call. The sales desk answers the same specification question repeatedly and files it under service, because the catalogue was never expected to answer it. That is a reasonable thing to believe about a catalogue built from a price list, and it is no longer true about what buyers expect.
The spec is not missing. It is in a PDF, which is the same as missing to everyone except the person who already knows the part number.
Why this sector is the cheapest to fix
The distinguishing fact about distribution is that the data almost always exists. It arrived with the range, in a supplier datasheet, as a table in a PDF. Nobody mapped it into a field because nobody needed it in a field while part-number search was sufficient.
That makes most of the work mapping rather than acquisition, and the two differ by an order of magnitude in cost. The question worth answering before budgeting is which of your gaps are which.
The argument that lands internally
Specification search is not a better version of part-number search. It serves a different customer: the one evaluating you against an alternative, and the one specifying a new build who has no incumbent relationship with you at all.
Part-number search serves the customers you already have. Specification search is how you get the next ones, and it is also the most direct route to reducing the load on a sales desk that is currently acting as the catalogue's query interface.
We will not put a number on that reduction, because we have not measured one on your traffic. The questions your desk repeats every week are a good place to point the measurement.