焊接式止回阀又称为逆流阀、逆止阀、背压阀、单向阀。这类阀门是靠管路中介质本身的流动产生的力而自动开启和关闭的，属于一种自动阀门。止回阀用于管路系统，其主要作用是防止介质倒流、防止泵及其驱动电机机反转，以及容器内介质的泄放。焊接式单向阀只允许介质向一个方向流动，而且阻止方向流动。

       公称压力：PN2.5 PN4 PN6.4 PN16 PN40Mpa
       公称通径：DN5～DN125
       适用介质：油﹑水﹑气等多种非腐蚀性或腐蚀性介质
       适用温度：-20℃～+440℃ -70℃～-240℃ ≤540℃ ≤570℃等
       制造材料：20#﹑1Cr18Ni9Ti﹑304﹑316﹑316L﹑12Cr1Mov等

外螺纹焊接止回阀

外螺纹焊接止回阀是一种阀体端部加工有外螺纹（Male Thread），并通过焊接方式与管道系统实现长久性连接的止回阀。这种独特设计率先通过螺纹进行快速定位与预紧，通过焊接实现高强度密封，融合了螺纹连接的便捷性与焊接连接的稳定性。其核心功能是自动允许流体单向通过，并高有效阻止介质反向流动，广泛应用于石油、化工、电力等行业的中高压、小口径关键管路。

该阀门的安装分为两个步骤：将阀门的外螺纹与管道或管件上的内螺纹进行旋合，实现初步紧固与对中；随后，在螺纹连接处的承插接口或坡口进行密封焊接（通常为角焊或对焊），形成一种不可拆卸的、零泄漏的长久连接。这种 hybrid（混合）连接方式比单纯的螺纹连接更耐振动和高压，比完全的对焊更易于安装。

外螺纹焊接止回阀主要特点：

双保险密封机制： 螺纹提供机械预紧与初始密封，焊接提供的长久性金属密封，密封等级极高，远超单一连接方式。

结构紧凑强度高： 承插焊或对接焊结构使其体积小巧，重量轻，同时能承受极高的压力（如Class 3000, Class 6000）和强烈的压力波动。

外螺纹焊接止回阀安装便捷对中准： 螺纹起到了天然的导向和定位作用，使焊接前的对中调整变得非常简单，降低了安装技术难度。

抗振动与冲击： 焊接连接消除了接头松动的风险，使其在振动、冲击工况下性能极其稳定。

经济有效： 省去了法兰、螺栓和垫片，减少了潜在的泄漏点，降低了总体拥有成本。

外螺纹焊接止回阀典型应用：

外螺纹焊接止回阀石油天然气行业：井口装置、高压仪表管线、取样系统。

外螺纹焊接止回阀化工与石化：高压小型工艺管线、反应器进出口、催化剂注入线。

外螺纹焊接止回阀电力工业：锅炉给水小口径阀门、高压蒸汽取样系统。

外螺纹焊接止回阀船舶制造与海洋工程：紧凑空间内的液压与燃油系统。

外螺纹焊接止回阀各类中高压、小口径且不允许泄漏的苛刻工况。

Product Overview of Male Threaded Welded Check Valves

Product Overview:

A Male Threaded Welded Check Valve is a type of check valve with external male threads machined on its body ends, designed to achieve a permanent connection to the piping system through welding. This unique design first utilizes threads for rapid positioning pre-tightening, ultimately relies on welding for high-strength sealing, perfectly combining the convenience of threaded connections with the reliability of welded joints. Its core function is to automatically allow unidirectional fluid flow efficiently prevent reverse flow of media. It is widely used in medium-high pressure, small-bore critical pipelines in industries such as oil, chemical, power.

The installation is a two-step process: First, the valve's male threads are screwed into the female threads of the pipe fitting to achieve initial tightening alignment. Subsequently, a sealing weld (typically a fillet weld butt weld) is applied at the socket bevel of the threaded connection, forming a non-demountable, zero-leakage permanent joint. This hybrid connection is more resistant to vibration high pressure than a threaded-only connection easier to install than a full butt weld.

Key Features:

Dual-Sealing Mechanism: The threads provide mechanical preload initial sealing, while the welding provides the final permanent metallic seal, offering an extremely high sealing integrity far exceeding that of a single connection type.

Compact High-Strength Structure: The socket weld butt weld design makes it small lightweight, yet capable of withstanding very high pressures (e.g., Class 3000, Class 6000) severe pressure fluctuations.

Easy Installation Precise Alignment: The threads act as a natural guide locator, making alignment before welding straightforward reducing the technical difficulty of installation.

Vibration Shock Resistance: The welded joint eliminates the risk of connection loosening, making it exceptionally stable under vibrating shocking conditions.

Cost-Effectiveness: Eliminates the need for flanges, bolts, gaskets, reduces potential leak points, lowers the total cost of ownership.

Typical Applications:

Oil & Gas Industry: Wellhead equipment, high-pressure instrument lines, sampling systems.

Chemical & Petrochemical: High-pressure small-bore process lines, reactor inlet/outlet lines, catalyst injection lines.

Power Industry: Small-bore valves in boiler feedwater systems, high-pressure steam sampling systems.

Shipbuilding & Offshore Engineering: Hydraulic fuel oil systems in compact spaces.

Various medium-high pressure, small-bore severe services leakage is unacceptable.

关键术语翻译 (Key Terminology Translation):

外螺纹焊接止回阀: Male Threaded Welded Check Valve

外螺纹: Male Thread / External Thread

焊接: Welding

承插焊: Socket Weld (SW)

对焊: Butt Weld (BW)

角焊: Fillet Weld

坡口: Bevel

预紧: Pre-tightening / Preload

对中: Alignment

零泄漏: Zero Leakage

苛刻工况: Severe ServiceOffshore Platforms & Ships: Piping systems space is limited safety requirements are extremely high.

关键术语翻译 (Key Terminology Translation):

美标焊接止回阀: American Standard Welded Check Valve

对焊连接: Butt Weld Connection / Butt-Welded End (BWE)

焊接坡口: Weld Bevel / Beveled End (for welding)

锻件: Forging / Forged Body

铸件: Casting / Cast Body

材料牌号: A105 (碳钢锻件), A216 WCB (碳钢铸件), A182 F316 (不锈钢锻件)

旋启式: Swing Type

升降式: Lift Type

零泄漏: Zero Leakage

压力-温度额定值: Pressure-Temperature Rating

苛刻工况: Severe Service