Overview
Union bolt fasteners are specialized mechanical connectors designed to join sections of piping while allowing for future disconnection. Unlike permanent welding or threading, these fittings use a nut-and-bolt mechanism to clamp sealing surfaces together, creating a robust yet serviceable joint. Primarily used in industrial fluid systems, these components solve the challenge of maintaining pressurized pipelines that require periodic maintenance. Their design typically includes three parts: a central body with pipe threads, a gasket or sealing surface, and a bolted flange that compresses the assembly.
Structure and Working Principle
The standard union bolt fastener consists of a female threaded body, a male threaded counterpart, and a hexagonal nut that draws the two halves together. Between the mating surfaces sits a deformable gasket (often rubber or PTFE) that forms the actual seal when compressed. When the nut is tightened, it forces the flanged ends of both pipe sections against the gasket with evenly distributed pressure. This creates a metal-to-gasket-to-metal sandwich that prevents leakage even under high internal pressure or vibration conditions. The bolt pattern (usually 2, 4, or 6 bolts) determines the clamping force distribution.
Key Features
Modern union bolt fasteners offer several advantageous characteristics for industrial applications. Their material options provide chemical compatibility - stainless steel for corrosive fluids, brass for potable water, and carbon steel for high-pressure oil/gas systems. These fittings maintain their sealing integrity through thermal cycling and vibration better than threaded joints. The bolted design allows for precise torque application, with many models including torque value markings. Some high-end variants feature self-aligning flanges or built-in anti-vibration washers for challenging installations.
Application Areas
Union bolt fasteners see widespread use across multiple industries due to their reliability and serviceability. In water treatment plants, they connect filter housings and pump discharge lines where regular membrane replacement is needed. The oil and gas industry employs heavy-duty versions for wellhead equipment and pipeline junction points. Chemical processors utilize specialty alloy unions for acid lines. Even HVAC systems use these fittings for chiller connections that require seasonal servicing. Their versatility makes them indispensable in any piping system expecting future modifications.
Maintenance and Precautions
Proper maintenance ensures long-term performance of union bolt connections. During installation, always use a calibrated torque wrench to achieve the manufacturer's specified values - under-tightening causes leaks while over-tightening may crush gaskets or warp flanges. Inspect gaskets during disassembly and replace if showing compression set or chemical degradation. For systems with thermal cycling, consider retorquing after initial heat exposure. Always match gasket material to the process fluid - EPDM for hot water, Viton for oils, and Kalrez for aggressive chemicals.
B2B Procurement Guide
When sourcing union bolt fasteners wholesale, specify these critical parameters: nominal pipe size (NPS), pressure class (e.g., 150# or 300#), material grade (ASTM A182 F304 for stainless), and facing type (RF for raised face). Bulk purchases typically offer 20-35% cost savings over single units. Leading manufacturers include Parker Hannifin, Swagelok, and GF Piping Systems. For custom requirements, provide CAD drawings showing bolt circle diameter, flange thickness, and special coatings like Xylan for friction reduction.
Related Manufacturers
- 主营：[]
- 主营：缩梗螺栓、扭剪螺栓、双头螺栓、预埋螺栓、大六角螺栓、高强度螺栓、双头螺纹螺栓、地脚螺栓、预埋件、全螺纹螺柱
- 主营：[]
- 主营：[]
- 主营：自攻螺丝、燕尾螺钉、圆形弹垫、螺栓螺丝、六角螺栓、焊接螺栓、螺栓垫片、双头螺栓、注塑螺栓、自钻螺钉、螺母垫片、活节螺丝、六角螺母、法兰螺母、加大平垫、六角螺丝、法兰螺帽、化学锚栓、压板螺母、自钻螺丝、钻尾螺钉、拉铆螺母、导向螺钉、钻尾螺丝、螺丝螺母
- 主营：[]
- 主营：热镀锌螺丝、热镀锌连接副、锚栓、钢结构大六角螺栓、钢结构扭剪型螺栓、热镀锌螺栓、热渗锌螺栓、热镀锌高强度螺栓、地脚螺栓、预埋地脚螺栓、地基锚固螺栓、大六角头螺栓、高强度大六角螺栓、10.9级扭剪型螺栓、扭剪型螺栓、扭剪型高强度螺栓、扭剪螺栓、国标热镀锌螺栓、热镀锌紧固件、风电螺栓、基础地脚螺丝、设备地脚锚栓、预埋锚栓
- 主营：[]
- 主营：短网系统、水冷电缆、水冷护屏、调节螺栓、导电元件、水冷大套、波纹管油缸、锻造铜瓦、冶金设备
- 主营：铜镍合金、镍基合金、高温合金、螺栓紧固件、圆钢、无缝管、钢板、钢带、弯头、三通、法兰、抓斗
- 主营：铝合金铆钉、六角螺母、方螺母、六角螺栓、四方螺栓、活节螺栓、圆柱头螺丝、内六角螺丝、十字自攻、沉头螺丝、圆头螺钉、平垫、弹垫、梅花螺钉、非标螺丝、紧定、自攻螺丝、T型螺丝、圆柱销、铆螺母、钻尾螺丝、挡圈、牙条、牙棒
- 主营：内六角、加厚平垫、六角螺母、膨胀螺栓、定制螺栓、双头螺栓、外六角螺栓、拉杆紧固件、紧固件螺栓、车削壁虎螺栓、定制加长螺栓、加大平垫、六角螺丝、合金螺丝、六角十字三、不锈钢螺帽、六角法兰面、实心铝拉杆、不锈钢垫片、梯形扣丝杠、不锈钢卸扣、螺丝彩钢瓦钉、不锈钢半球门、扁头自攻螺丝、不锈钢平垫片
- 主营：球拍螺丝、非标螺丝、异形螺丝、活接螺丝、非标螺栓、球拍螺栓、双头螺栓、台阶螺栓、法兰螺栓、四方螺栓、家具螺丝、手拧螺丝、母指螺丝、双头螺丝、马车螺丝、自攻螺丝、非标连接件、异形铆钉、六角螺母、非标冷镦件、鱼眼垫圈
- 主营：三组合螺钉、不锈钢螺丝、304 螺丝、六角螺栓、六角螺母、平垫、弹垫、十字沉头、内六角螺丝
- 主营：家具螺丝、沉头、自攻丝、高强度螺栓、螺母、铜螺丝、开口销、平弹垫、四爪母、内外牙、平键、建筑类螺丝、全扣丝
- 主营：铜镍合金、哈氏合金、高温合金、Monel400、双相钢、奥氏体不锈钢、N06617、GH3128、BZn15-20锌白铜管、GH3044、C75200、GH3039仪表管、GH3030冷轧板、Cr20Ni80带材、钨合金、钨镍铁合金
- 主营：垫圈、波形垫圈、双自锁垫圈、非标螺丝、不锈钢螺丝、挡圈、防松垫圈
- 主营：定位销、GB1096平键、GB1097平键、非标螺栓、304平键、不锈钢平键、导向平键
- 主营：316LMoD、316LN、GH3536、SUH660紧固件、GH3128、GH3030、GH3039、CuNi44
- 主营：镍基合金法兰、不锈钢管件、特种不锈钢、哈氏合金紧固件、六角螺栓、紧固件、定制螺栓法兰、蒙乃尔合金、GH4169、2507、高温合金、253MA、不锈钢法兰、锻件法兰、封头、管件、对焊法兰、平焊法兰、盲板、弯头、三通、2205、耐腐蚀合金、大小头管件、耐腐蚀法兰