Use this guide to prepare a clearer technical request. Final manufacturing feasibility is confirmed against the complete RFQ, drawings and project specification.
Do not specify by nominal size alone
Different thread systems can share a nominal size while using different flank angles, pitch, taper and sealing methods.
Separate tapered and parallel threads
NPT and BSPT are tapered systems. BSPP is parallel and normally relies on a separate sealing face or washer selected for the joint design.
Define metric threads completely
State diameter, pitch, tolerance class and sealing arrangement. The word metric alone does not define an interchangeable connection.
Identify the mating part
For replacements, provide the mating component drawing, gauge result or a clear sample. Photographs alone rarely establish thread geometry.
Put inspection in the RFQ
Agree applicable gauges, engagement criteria, thread protection and cleanliness before production.
Standards can be revised and projects may add special requirements. State the designation, edition and supplementary conditions in the RFQ.