OEM manufacturer ASME B16.11 · ASME B1.20.1
Hex Head Bushings — ASME B16.11
A hex head bushing reduces a female-threaded opening to a smaller female thread. Teshi Group manufactures hex head bushings to ASME B16.11, with NPT threads to ASME B1.20.1, in carbon, low-temperature, alloy and stainless steels.
Also called: hex bushing, reducing bushing, threaded bushing, NPT bushing, pipe bushing
What is a Hex Head Bushing?
A hex head bushing has a male thread on the outside, a smaller female thread on the inside and a hex for tightening. It screws into a fitting, valve or equipment connection and lets a smaller pipe, gauge or instrument be connected without a separate reducer. ASME B16.11 covers hex head and flush bushings without a pressure class designation. Bushings are compact but reduce the bore abruptly, so they are mostly used on instrument and utility connections.
Key features
- Hex head bushings per ASME B16.11
- NPT male and female threads per ASME B1.20.1
- Compact reduction without a separate reducer
- Machined from forgings or bar
Specification
| Supply | OEM manufacturer — Teshi Group, India |
|---|---|
| Standard | ASME B16.11 |
| Pressure class | Not class-designated in ASME B16.11 |
| Size range | Outside thread NPS ¼"–4", with smaller inside thread |
| Threads | NPT per ASME B1.20.1; BSPT (ISO 7-1) on request |
| Materials — carbon steel | ASTM A105 / A105N; ASTM A181 Cl 60, Cl 70; ASTM A266 Gr 2, Gr 4 (large forgings) |
| Materials — high-yield carbon steel | ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70 (MSS SP-44 grades F52–F70) |
| Materials — low-temperature carbon steel | ASTM A350 LF1, LF2 Cl 1, LF2 Cl 2, LF3, LF6, LF9 |
| Materials — alloy steel (Cr-Mo) | ASTM A182 F1, F2, F5, F5a, F9, F11 Cl 1 / 2 / 3, F12 Cl 1 / 2, F21, F22 Cl 1 / 3, F22V, F91, F92, F911; ASTM A336 F11, F22 (large forgings) |
| Materials — stainless steel | ASTM A182 F304, F304L, F304H, F304LN, F309H, F310, F316, F316L, F316H, F316LN, F316Ti, F317, F317L, F321, F321H, F347, F347H, F348 |
| Materials — 904L and 6Mo | 904L (ASTM A182 F904L, UNS N08904); 254 SMO / 6Mo (ASTM A182 F44, UNS S31254); AL-6XN (ASTM A182 F62, UNS N08367) |
| Materials — duplex stainless steel | ASTM A182 F51 (UNS S31803), F60 (UNS S32205, 2205) |
| Materials — super duplex stainless steel | ASTM A182 F53 (UNS S32750, 2507), F55 (UNS S32760), F61 (UNS S32550) |
| Materials — nickel alloys | ASTM B564 / B160 / B462: Nickel 200 / 201 (N02200 / N02201), Monel 400 (N04400), Monel K-500 (N05500), Inconel 600 (N06600), Inconel 625 (N06625), Inconel 718 (N07718), Incoloy 800 / 800H / 800HT (N08800 / N08810 / N08811), Incoloy 825 (N08825), Hastelloy C276 (N10276), Hastelloy C22 (N06022), Hastelloy B2 / B3 (N10665 / N10675), Alloy 20 (N08020) |
| Materials — titanium | ASTM B381 Grade F1, F2, F5 (Ti-6Al-4V), F7, F12 |
| Materials — copper-nickel | Cu-Ni 90/10 (UNS C70600) and 70/30 (UNS C71500), ASTM B151 bar; flanges to ASME B16.5 or EEMUA 145 |
| Grade availability | Every grade listed is made or supplied against order, with EN 10204 3.1 certificates (3.2 / third-party inspection when specified) and PMI on alloy, stainless, duplex and nickel grades. |
| Testing | Visual, dimensional and thread/socket gauge inspection; PMI on alloy and stainless grades; hardness check; MPI/DPT when specified |
| Documents | EN 10204 3.1 mill test certificate; 3.2 / third-party inspection when the order specifies; dimensional inspection report; IBR certification for boiler/steam service when specified |
Applications
- Gauge and instrument connections
- Reducing threaded equipment ports
- Utility and instrument air lines
- Valve drain and vent connections
Hex bushing vs threaded reducing coupling
A hex bushing screws into an existing female port and reduces it, adding almost no length to the assembly. A threaded reducing coupling sits between two male pipe ends and adds a fitting length. Use a bushing to connect a smaller line or instrument to an existing port; use a reducing coupling for an in-line size change between two pipes. Some piping specifications limit bushings to one size reduction.
FAQ
Hex Head Bushing: common questions
What is the difference between a hex bushing and a hex nipple?
A hex bushing has an outside male thread and an inside female thread. A hex nipple has male threads on both ends with a hex in the middle.
Do bushings have a pressure class?
No. ASME B16.11 does not assign class designations to bushings. Choose the bushing material to match the parent fitting, valve or equipment port, as per the piping specification.
Can a bushing reduce by more than one size?
Yes. Bushings are made in a range of outside and inside thread combinations, so one bushing can step down more than one size. State both thread sizes in the enquiry.
How should bushing threads be sealed?
Use a thread sealant or PTFE tape suited to the service on NPT threads and tighten to normal make-up. For hazardous, cyclic or high-temperature service, many piping specifications require threaded joints to be seal welded.
Need a size or grade not listed here?
Our engineering team manufactures against your drawing or datasheet, with dimensional sign-off before dispatch.
Send us your specificationTraceability
From mill heat to your site
- 01
Approved mill material
Received against the mill certificate; heat number registered.
- 02
Forging & machining
Heat number carried through every stage in our Indian works.
- 03
PMI, dimensional & NDT
Every lot inspected to the governing standard; TPI witness on request.
- 04
Stamped & certified dispatch
Hard-stamped pieces with EN 10204 3.1 / 3.2 certificates.
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