1/4-20 — Minimum Size, Tight-Access Precision

Core Info

 

1/4-20 UNC heavy hex nut, ASTM A194 Grade 2H, cold forged from 45K medium-carbon steel, quenched and tempered, then finished with an eco-grade Dacromet zinc-aluminum flake system in place of thick galvanizing. Per ASME B18.2.2 heavy-hex, it measures 1/2 in (12.7 mm) across flats and about 15/64 in (6.0 mm) tall; the internal thread is 1/4-20 UNC, class 2B. This is the smallest size ASTM A194 covers, yet it remains a pressure-bolting component: heavy-hex proof load is 175 ksi and hardness is controlled near 248–327 HB, with A193 B7 as the standard mating stud. At this diameter, tolerances are tight, so qualify each lot by proof-load test and post-coating thread gauges, protect the bearing face from burrs, and keep thread engagement at about one nominal diameter or more so the nut threads are not stripped before the stud yields.

 

Its territory is precision equipment with limited swing room: analyzer cabinets, instrument tubing headers, small valve bodies, gauge and relief-valve adapters, sampling cylinders, panel-mounted devices and light turbine accessories. Compared with its larger siblings it develops lower absolute preload and tighter spacing, so alignment, hole condition and a qualified lubricant govern achieved tension more than wrench size. The 20 TPI form is the finest here, giving finer position adjustment and steady flank support on short screws. A slim 1/2 in socket or nut driver reaches into crowded enclosures, the flake film curbs rust staining indoors; for chemical splash, freeze-thaw salt or offshore fog, specify a sealed duplex coat and requalify the friction coefficient.

Classified by property class as follows：

Main Sales Markets of the Product:Europe, the Middle East and Southeast Asia

We are certified by ISO9001:2015, IATF16949:2016, and other international quality standard certifications.

Long-term quality warranty and comprehensive after-sales service are provided.

Established in 2005, our company has evolved over two decades of continuous development into a leading regional enterprise in the fastener industry with fully automated end-to-end production. With an annual output value exceeding RMB 130 million, our product range covers diverse market segments from mid-range to high-end and is distributed worldwide

 

Our factory & quipment

 

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