Do you often see “U-shaped bolts” in various places at manufacturing sites, such as fixing pipes in factories or the undercarriage of vehicles? That is the “U-Bolt” we will explain this time. Although it looks like a simple shape, it is actually one of the fasteners with the most ordering mistakes due to the difference between “nominal diameter” and “actual size.”

Especially in manufacturing sites in Vietnam, selecting materials compatible with the high-temperature, high-humidity climate and procuring special sizes for sudden equipment maintenance tend to be challenges. In this article, from the perspective of a procurement professional that Ohta Vietnam has cultivated over many years, we will explain the basic knowledge of U-bolts, how to read standards, and selection points suitable for Vietnam’s unique environment in an easy-to-understand manner in 3 minutes. Let’s acquire the correct knowledge and prevent procurement mistakes and on-site troubles before they happen.

As the name implies, a U-bolt is a bolt bent into the shape of the alphabet “U”, featuring threads cut on both ends. While a general hex bolt “tightens and joins two members,” a U-bolt is mainly used to “embrace and fix pipe-shaped objects to a mount or wall surface.”

It plays an important role not only in physical support capacity but also in preventing pipe displacement or falling off due to vibration, and its uses are diverse.

When selecting a U-bolt, it is essential to understand the following four dimensional elements.

The most common mistake in ordering U-bolts is confusing the pipe’s “Nominal Diameter (A)” with the “Actual Size (mm).”

For example, when ordering a “U-bolt for 50A pipe,” the inner width of the U-bolt is not approximately 50mm. The “50A” for carbon steel pipes for ordinary piping in JIS standards (JIS G 3452, etc.) is defined as having an outer diameter of 60.5mm. Therefore, the inner width of a U-bolt for 50A needs to be 60mm or more (usually with a clearance of a few mm) to accommodate this.

If you say, “I bought a 50A U-bolt because I want to fix a round bar with a diameter of 50mm,” the size will be too loose to fix it. Be sure to check the “Outer Diameter (OD) of the object to be fixed” and select a size that fits it.

Although the demand for ship-related repair parts is high in Vietnam, dimension standards may differ between “for general piping” and “for marine use (JIS F 3022, etc.).” Marine use is generally designed to be thicker and stronger to withstand vibration and impact. It is necessary to note that the catalog to be referenced differs depending on whether the application is a land plant or an offshore facility.

In general indoor environments, iron (SS400 equivalent) with unichrome plating (silver) or chromate plating (yellow) is used. While excellent in cost performance, rust occurs easily in high-humidity environments. Since the average humidity in Vietnam exceeds 80%, caution is required even indoors in factory areas without air conditioning.

Recommended in the Vietnam market is stainless steel, which has excellent corrosion resistance.

With off-the-shelf U-bolts, requests such as “I want longer legs because I want to lay a thick rubber mat under the pipe” may not be met. At Ohta Vietnam, through cooperation with our own factory and partner factories, it is possible to manufacture custom U-bolts where leg length (L dimension) and thread length can be specified in millimeter units. We flexibly respond to prototypes from one piece and orders for high-mix low-volume production.

If standard U-bolts are needed for sudden maintenance, as an authorized distributor of Trusco Nakayama (TRUSCO), we can quickly supply products from the vast inventory listed in the “Orange Book.” The convenience of purchasing Japanese-quality products in local Vietnamese currency is highly evaluated by many Japanese companies.

We conduct quality checks on received fastener products using our own inspection equipment. In the future, we aim to provide “fastening solutions” that go beyond mere parts supply, such as set supply with anti-loosening nuts (Hard Lock Nut, etc.) and proposals for IoT sensor bolts that monitor the fastening axial force of important pipelines.

U-bolts are the unsung heroes supporting the stable operation of factories. However, incorrect size selection or material choice carries the risk of leading to pipe breakage or serious accidents.

Ohta Vietnam responds to all your “fastening” needs, from immediate delivery of standard products to manufacturing of special specifications. If you have any concerns regarding pipe support or fixation, please feel free to consult us.

Conclusion

For inquiries regarding samples or materials, please respond to this email or contact our sales representative!

At Ohta Vietnam, we not only provide ready-made products such as screws and bolts, but also support activities in the manufacturing field such as cutting, inspection, assembly, packaging…
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As a “specialized support” for the manufacturing industry in Asia. If you have any related questions, feel free to contact Ohta Vietnam for detailed support!
URL: https://ohtavn.com/en/contact/