PRODUCT FEATURES
Union Welding End & External Thread — Product Features
Suitable for water supply and drainage, water treatment equipment, general chemical piping, fire protection systems, mechanical piping, food and light industry applications, construction piping, and pump and valve connection assemblies.
Product Feature
Notes
Product Feature
Material test certificates (EN 10204 3.1) are available for bulk orders. OEM and custom branding services are supported. Samples can be provided for quality verification prior to bulk ordering. Thread type and dimensions must be confirmed before production to avoid installation mismatches on-site.
OPERATING PRINCIPLE
How Union Welding End & External Thread Works
1. Dual-Connection Design: One end features a socket-weld connection for permanent pipe welding, while the other end features a male threaded connection (available in NPT or BSPT) for attaching valves, pumps, or other threaded fittings.
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2. Cast Construction
Offers high mechanical strength and stable performance under pressure, with excellent resistance to porosity or cracking.
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3. 304 Stainless Steel
Provides superior rust resistance, making it suitable for freshwater applications, mildly acidic environments, and outdoor piping systems.
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4. Easy Maintenance
Designed as a three-piece union, allowing for quick disassembly whenever pipe cleaning or repairs are required.
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5. Tight Sealing
The sealing surfaces are precision-machined to ensure reliable, leak-free performance at rated operating pressures.
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6. Thread Specifications
Supports NPT or BSPT tapered pipe threads, selectable based on specific project requirements.
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7. Size Range
1/4″ to 4″ (DN8 to DN50); custom sizes are also available upon request.
ENGINEERING DATA
Technical Specifications
Technical data supplied for UNION welding end & external thread. Ratings and material combinations should be confirmed for the selected configuration.
| PARAMETER | SPECIFICATION |
|---|---|
| – Material | AISI 304 (ASTM A182 F304) |
| – Type | Weld × Male Thread Union (Socket Weld to Male Thread Union) |
| – Thread Standard | NPT (ANSI B1.20.1) / BSPT (BS EN 10226-1) |
| – Pressure Rating | 150LB (MSS SP-83) |
| – Surface Finish | Pickled and passivated; smooth machined surface |
| – Manufacturing Standard | MSS SP-83, ASME B16.11 |
| – Operating Temperature | -20°C to +120°C |
MECHANICAL DIMENSIONS
Dimensions & drawings.
Compare connection size with the corresponding overall length, bore and handle clearance dimensions from the supplied drawing.
Dimension chart
| SIZE | L | A | B |
|---|---|---|---|
| 1/2 | 53 | 21 | 20 |
| 3/4 | 59 | 27 | 26 |
| 1 | 64 | 34 | 32 |
| 11/4 | 70 | 42 | 41 |
| 11/2 | 75 | 48 | 47 |
| 2 | 84 | 60 | 59 |
Refer to the supplied dimension chart.
APPLICATIONS
Applications
Applicable media: the supplied document lists the following fluids. Actual compatibility depends on selected materials, concentration, temperature, pressure and the specific service conditions.
Application – Water Circulation
Cooling water, circulating water, drinking water and neutral purified water.
Application – Steam Piping
Clean, low-temperature saturated steam, subject to the product’s confirmed temperature and pressure limits.
Application – Compressed Air
Compressed air and nitrogen; verify compatibility for each system.
PURCHASING SUPPORT
Frequently Asked Questions
Find answers to common questions about sizing, materials, threaded connections and operating conditions.
What is a 304 weld-end male-thread union?
Answer: This is a pipe union made of AISI 304 stainless steel. One end is designed for socket-weld connection to a pipe, while the other features a male thread for threaded connection. It allows for the convenient disassembly of piping systems—without the need to cut the pipes—to facilitate maintenance. It is also referred to as an SS304 weld-end male-thread union.
What is the material grade? Can an MTR (Material Test Report) be provided?
Answer: The standard material is AISI 304 (ASTM A182 F304). An MTR/material certificate, which includes data on chemical composition and mechanical properties, can be provided upon request. We also offer products in 304 or 316L grades.
What material grades are available?
Answer: Stainless steel: ASTM A182 F304 / F304L / F316 / F316L.
All raw materials come with an MTC (Mill Test Certificate) and a PMI (Positive Material Identification) report to meet the buyer’s traceability requirements.
What are the pressure ratings/working pressures?
Answer: Standard 304 weld-end male-thread unions are typically rated as Class 150 or Class 3000; the maximum working pressure varies based on temperature. Every batch undergoes hydrostatic testing.
What thread standards are supported?
BSPT, BSPP (G), or NPT standards are supported. Please specify the required thread type when placing an order.
What is the size range?
1/8 inch to 4 inches.
What documentation and certificates can be provided for customs clearance and on-site inspection?
Answer:
– MTC (Mill Test Certificate, for ASTM material traceability)
– PMI (Positive Material Identification report)
(These must be requested in advance; additional costs and longer lead times may apply.)
Why might a pipe union leak after installation? A: Common causes include:
1. Mismatched thread standards (e.g., NPT vs. BSP)
2. Overtightening or undertightening
3. Damaged PTFE (polytetrafluoroethylene) gasket
4. Scratches on the sealing surfaces
Avoid applying excessive torque to stainless steel threads to prevent galling (seizing).
What is the Minimum Order Quantity (MOQ)?
Small-batch orders are accepted, and different product specifications can be mixed within a single order.
What is the lead time?
Typically, orders are shipped within 7–15 days of receiving the deposit, depending on the order quantity.
How do you ensure quality control?
Raw material inspection → CNC machining → Thread inspection → Hydrostatic testing → Visual inspection → Final dimensional check before packaging.
What Incoterms are available for overseas buyers?
We offer FOB (Free On Board) terms from Chinese ports. We will provide a commercial invoice, packing list, and bill of lading for import customs clearance.
What Incoterms are available for buyers?
We offer FOB (Free On Board) terms from Chinese ports or CIF (Cost, Insurance, and Freight) terms. We will provide a commercial invoice, packing list, and bill of lading for customs clearance.
What should be done if defects in the threads or non-compliance with requirements are discovered upon arrival of the goods?
Please provide photos, videos, and inspection records. We will assess the root cause; depending on the contract terms, solutions may include product replacement, a partial refund, or a reshipment of goods.
UNION welding end & external thread
304 Stainless Steel UNION welding end & external thread(NPT/BSPT options available)
This SS304 union features a socket weld connection on one end and a male threaded connection on the other, facilitating easy disassembly for pipeline maintenance. Corrosion-resistant and rated for 150LB pressure, it is widely used in waterworks, industrial applications, and piping systems. Material Test Certificates (MTC) are available.
Type: UNION welding end & external thread
Material: 304/316L stainless steel
Nominal diameter: 1/4”–2” (D8–DN50)
Rated pressure: 1.6 MPa (PN16)
Connection type: Threaded connection (BSPT / BSPP / NPT)
