One of the great things about Fabrication is its infinite expandability. One of the worst things about Fabrication is its infinite expandability.
Users can specify a material such as stainless as Stainless, stainless, SS316, Stainless Steel, etc. Connectors could be weld, Weld, WeldGap, etc. The choices are infinite. Also, as the connectors (and also potentially the material) controls what connects to what and how, there can be a lot of problems.
Solution 1 would be to build and maintain your own library of parts.
Solution 2 would be to use something like MEPContent which has millions of pre-built and maintained libraries of components from manufacturers.
MEPContent is, I believe, the only 'protected/locked' content that Autodesk has authorized. The idea is that the library is incorruptable. Everything should connect as designed by the manufacturer. The downside is that it is very difficult to 'cheat' and you are stuck with the pre-designated names for materials, connectors, etc. You can certainly add your own 'custom' components to Services but, it is much easier to use the MEPContent materials and connectors for your components rather than the other way round. For things like material names, you could use the Abbreviation parameter that each material has.