A threaded fitting is only as good as its thread: cut concentric to the bore, to the full gauged length, in a forging with enough wall around the thread root. The catalogue execution on this page shows the pattern concretely: a forged plug at 3 inch, Class 3000, NPT, in A105.
Threaded systems are assembled with sealant or PTFE tape and can be broken and remade — the property that keeps them specified for utility headers, galvanised fire and water lines, air systems and temporary works, even in plants that weld everything else.
| Item | Range / Options |
|---|---|
| Standards | Confirmed per product at enquiry — catalogue execution: 3 inch Class 3000 NPT plug in A105 |
| Types | Plugs (catalogue execution: 3 inch, Class 3000, NPT, A105) |
| Size range | Catalogue execution: 3 inch; other sizes confirmed per product at enquiry |
| Pressure classes | Class 3000 in the catalogue execution; other classes assessed against your enquiry for the specific product |
| Materials | Carbon steel ASTM A105 in the catalogue executions referenced on this site; further grades confirmed per product at enquiry |
| Finish | Confirmed per product at enquiry |
Class Follows the Pipe Wall
Threaded classes pair with pipe walls just as socket weld classes do: on the correlation ASME B16.11 uses as its rating basis, Class 2000 goes with Schedule 80 / XS, Class 3000 with Schedule 160 and Class 6000 with XXS. The thread removes metal from the pipe, so the heavier the class, the heavier the pipe wall the correlation assumes. Ordering by class keeps the pairing straight. That correlation is the basis the ratings are calculated from, not a rule that only those walls may be used — other pipe walls can be used, with the rating then governed by the applicable piping code and by whichever of pipe or fitting controls.
Galvanised Systems
Threaded fittings are the natural joint for hot-dip galvanised pipe, where welding would burn the coating off. Where a galvanised execution is required, state it on the enquiry and it will be confirmed for the specific product. Fire water, cooling and general utility headers are the typical galvanised applications.
Honest Limits
Threaded joints can weep under severe thermal cycling and are restricted by most process specifications above small sizes or in hazardous service. Where the specification is silent and the service is severe, the socket weld system is the safer default. Where dismantling matters, threaded wins — the same plant often uses both, divided by service.
Frequently Asked Questions
NPT or BSPT — can I mix them?
No. NPT (60 degree, ASME B1.20.1) and BSPT (55 degree) threads differ in angle, pitch and taper practice and do not seal together reliably. Our standard execution is NPT; if your pipe carries BSPT, name it on the enquiry and the execution will be confirmed for the specific product. Confirm the thread system of your pipe before ordering.
Do threaded fittings need seal welding?
Not by default — the joint seals on the thread with sealant or tape. Some specifications add a seal weld after make-up for specific services; that is a project decision and should be stated if required.
What is a hex bushing used for?
It reduces a threaded outlet to a smaller thread size in one forged piece — for example from a 2 inch header tapping to a 1/2 inch instrument connection. Flush bushings do the same with no protruding hex where space is tight.
Can threaded fittings be reused after dismantling?
Generally yes, if the threads are undamaged and clean: inspect the thread flanks, remove old sealant, and remake with fresh sealant or tape. Fittings that have been over-torqued, galled or corroded should be replaced — a forged fitting is cheap insurance against a weeping joint.
Related Products
Threaded Flanges
The flanged form of the threaded joint — thread form confirmed per product.
Send Your Specification
Tell us the size, schedule or pressure class, material grade and quantity for the threaded fittings you need. MOQ and lead time are confirmed in the quotation for your exact specification.