Cap Nuts
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When exposed industrial threads protrude from machinery frames, pipeline joints, or chemical processing units, they introduce serious structural and safety hazards. These bare metal ends easily snag operator clothing, cause workplace scratching injuries, and collect corrosive moisture or chemical residue that leads to early rust lock. Sunmach manufactures high-performance Stainless Steel Cap Nuts and heavy-duty Duplex Cap Nuts also known as dome or acorn nuts to completely shield these vulnerable thread ends. Designed with a smooth, closed dome head, these specialized fasteners encapsulate the end of the bolt to provide a clean, snag-free surface while sealing out ambient moisture to keep internal thread tracks pristine and easy to maintain over a long service life. To ensure absolute structural safety and clean performance in sanitary, high-stress, and marine setups, we produce our entire hardware line using only pure, top-grade metals from audited global mills. We offer a versatile selection of premium materials, from cost-effective Stainless Steel Cap Nuts tailored for long-term outdoor weather and factory washdowns to high-capacity Duplex Cap Nuts made from certified Duplex 2205 raw materials that are exactly twice as strong as standard steel. Every production batch is rigorously checked in our laboratories through precise thread inspections, hardness testing, and complete batch traceability to guarantee long-term stripping resistance, providing a reliable, worry-free lifespan of up to 50 years.
Cap Nuts
Sunmach is one of the leading global manufacturer and supplier of Standard & Custom made Premium Nickel Alloys Cap Nuts engineered for the most critical industrial applications. We are an ISO 9001:2015 certified company, demonstrating our commitment to rigorous quality standards and consistent product excellence to deliver the best of the Nickel Alloys & Special Steel Fasteners.
Nickel Alloys Cap Nuts are manufactured by us from a range of high-performance & exotic materials such as : Hastelloy® C-276, Hastelloy® C-22, Hastelloy® B-2, Monel® 400, Monel® K-500, Inconel® 600, Inconel® 625, Inconel® 718, Titanium Grade 2, Titanium Grade 5, Titanium Grade 7, Duplex S31803, Duplex S32205, Super Duplex S32750 to various Stainless Steel grades of SS 304L, SS 316L SS 310, SS 310H, SS 347H, etc followed by Special Stainless Steel Grades such as 904L Stainless Steel, UNS N08904, DIN EN1.4539 Nitronic® 50, Nitronic® 60, UNS S21800, DIN EN, 254 SMO, UNS S31254, DIN EN 1.454, A4-80 Stainless Steel etc.
Sunmach’s extensive manufacturing capabilities and In-Stock Genuine & Authentic Raw Material availability allows us to support demanding industrial requirements with durable, corrosion-resistant, heat resistant & reliable Nickel Alloys Cap Nuts delivered dot in time to any corner of the world, supported by all required test certificates and with 100% traceability.
Nickel Alloy Cap Nuts Specifications
Using Advanced Hot Forming Technology, Our Nickel Alloys Cap Nuts are manufactured in various specifications including DIN, ISO, ANSI and IS standard in nominal diameters ranging from 1/4” to 3.4” (M6 to M20). We provide Cap Nuts in both Imperial and metric sizes to accommodate diverse application needs. Our Nickel Alloys Cap Nuts are specially engineered to withstand high temperature and high-pressure, ensuring superior strength and reliability.
Nickel Alloy Cap Nuts Application Industries
Sunmach serves a diverse range of markets including Chemical Processing, Semiconductor, Power Generation, Aerospace, Oil & Gas, Pharmaceutical, Food & Beverage, Marine, Pulp & Paper, Petrochemical & Refining, Air Pollution Control and Water Treatment.
Sizes
| Metric : | M6 to M20 |
| Imperial : | 1/4" to 3.4" |
| MOQ : | 1 Piece & Above |
| Certification : | EN 10204 3.1, EN 10204 3.2 (On Demand) |
Specification
| Bolt | DIN | ISO | ANSI | IS |
|---|---|---|---|---|
| Cap Nut | 931 | 4014 | B18.2.1 | 1364 |
Dimensions - Imperial
Dimensions - Metric
Frequently Asked Questions
Common questions about Sunmach Stainless Steel & Duplex Cap Nuts
A: You should choose Stainless Steel Cap Nuts if your assembly has exposed thread ends that could scratch workers, catch on clothing, or collect dirt and moisture. The smooth, closed dome head covers the sharp thread ends entirely, providing a clean appearance, improved workplace safety, and a barrier that keeps the bolt threads safe from environmental damage.
A: You should upgrade to Duplex Cap Nuts when your equipment operates in highly aggressive environments like offshore oil platforms, desalination plants, or chemical refineries. These heavy-duty components are specifically built using high-strength alloys that resist micro-cracking and thread stretching under massive pressures where standard hardware would fail.
A: Standard open nuts leave the end of the bolt open to the air, allowing rain, salt spray, or washing chemicals to pool inside the thread tracks. Because Duplex Cap Nuts feature a solid, single-piece dome with excellent saltwater resistance, they act as a physical roof that blocks moisture and corrosive chemicals from creeping down into the internal threads, preventing early rust freeze.
A: The most critical check is ensuring the protruding bolt thread is not longer than the internal depth of the cap nut dome. If the bolt is too long, it will hit the inside ceiling of the dome before the nut can fully tighten down against the joint face, leaving the assembly loose and unstable.
A: We ensure complete field reliability by subjecting both Stainless Steel Cap Nuts and Duplex Cap Nuts to strict laboratory checks that far exceed real-world use. We verify the internal thread depth for a flawless fit, pull them under massive weight loads to ensure the dome will not split away from the hex base, and run corrosion resistance evaluations to ensure they remain free of surface rust for decades.