Connections
Thread identification basics
A fitting description needs more than a size. Collect the connection specification and its sealing details before asking a supplier to identify a replacement.
Published · Updated
Start with the equipment record
Write down the manufacturer and exact model of the kit or component that needs a fitting. Keep a photograph of its label and any existing part reference with the enquiry. A familiar-looking brass connector is a useful clue, but its appearance does not identify its specification. Equipment made by different manufacturers can use connections that look similar while needing different components.
Separate information you can read from information you still need confirmed. For example, a part number printed in a manual is a firmer starting point than a size estimated from a photograph. If a reference is missing, say so. A clear description of an uncertainty is more helpful than silently turning an estimate into an order specification.
Distinguish the thread from the end connection
Swagelok’s identification guide considers diameter, pitch and whether the thread is tapered or straight. Those characteristics help distinguish thread standards. The guide also treats end connections and sealing arrangements separately. A thread description alone may therefore leave out information needed to identify the complete connection.
For a buying enquiry, ask which thread standard and nominal size the manufacturer specifies, whether the end is male or female, and how that connection is intended to seal. Do not treat a nominal size as a direct measurement of every visible surface. Record a manufacturer’s wording rather than replacing it with a shorthand description such as “standard fitting”.
Collect evidence without guessing compatibility
Clear photographs can help a supplier understand the enquiry. Include the whole component, readable markings and the visible ends. State which equipment it belongs to and why a replacement is needed. Photographs are supporting evidence; they are not a substitute for the relevant drawing, parts list or written manufacturer confirmation.
Ask for the replacement reference and the document that connects that reference to your exact model. If the answer supplies only a size, ask whether the sealing arrangement, material and complete component configuration have also been checked. Matching one characteristic does not establish that two fittings are interchangeable.
Keep the answer with the order
Retain the supplier’s response alongside the model identification and quoted part. If a proposed alternative differs from the original reference, record who confirmed it and the basis for that answer. This makes later replacement enquiries less dependent on memory and helps another person distinguish a confirmed component from a spare of uncertain origin.
This guide concerns identification and purchasing questions. It does not give connection, torque, sealant or field-testing instructions. Use the equipment manufacturer’s current documents and appropriate qualified support for those matters. The linked sources include US-oriented equipment material; they do not establish requirements for every country or water authority.