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unthreaded pipe flange & flange with threaded nipple | Manufacturer
<p><span style="color: rgb(51, 51, 51); font-family: "Noto Sans SC"; font-size: 18px;">Direct factory pricing on</span><span style="color: rgb(51, 51, 51); font-family: "Noto Sans SC"; font-size: 18px;"> </span><strong style="color: rgb(51, 51, 51); font-family: "Noto Sans SC"; font-size: 18px;">unthreaded pipe flanges</strong><span style="color: rgb(51, 51, 51); font-family: "…
SupplierCangzhou Weihuan Pipeline Equipment Co.,Ltd.www.weihuantube.com
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🏭 ASME B16.5 · EN 1092 · DIN · JIS Certified Manufacturer
Unthreaded Pipe Flange & Flange with Threaded Nipple | Manufacturer
Direct factory pricing on unthreaded pipe flanges and flanges with threaded nipple — engineered to ASME B16.5, EN 1092, and DIN standards. Trusted by procurement managers, technical directors, and operations teams across 20+ countries for high-load, corrosive, and thermally demanding piping systems.
⏱️48h Fast Quotation
🌍20+ Export Countries
✅ISO 9001 Certified
📍 Cangzhou Weihuan Pipeline Equipment Co., Ltd. — Production facility
📑 Table of Contents
1. Industry Challenges2. Our Differentiator3. Technical Specifications4. Unthreaded Pipe Flange5. Flange with Threaded Nipple6. Engineering Data7. Applications8. Manufacturing & QC9. FAQ10. Reviews11. Author
⚡ The Real Cost of a “Cheap” Flange — What 2026 Buyers Face
We talk to purchasing and engineering teams daily. These are the recurring bottlenecks we see across the US, Europe, and the Middle East:
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Price Inflation up to 40%
Multi-tier distribution networks add 20–40% to flange costs before you even receive a quotation. In a year of volatile steel pricing, that margin is unacceptable.
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Quality Inconsistency
Traceability gaps on material test certificates (MTCs/EN 10204 3.1) create compliance headaches. Non-conforming heat treatment leads to premature cracking and costly downtime.
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Hidden Shipping Shock
Freight and port surcharges often exceed the quoted FOB price by 15–25%. Without consolidated logistics, buyers absorb unpredictable LCL premiums and customs delays.
📉
Mismatched Specifications
A flange may be dimensionally correct but have the wrong facing finish, wrong thread type (NPT vs BSPT), or improper nipple length — causing assembly failure on-site.
Quick reality check: In 2025, a European EPC contractor reported a 37% budget overrun on connector components due to rework from non-certified flange deliveries. The fix is not “cheaper” — it is a certified, factory-direct partner.
→ Request our compliance checklist to audit your current supplier
🏆 Why Procurement & Engineering Teams Choose Cangzhou Weihuan
As a platform-based supply chain management enterprise, we combine direct manufacturing control with a dedicated export sales team. We are not a trading company that forwards your inquiry to five different factories — we are the factory and the exporter, with unified responsibility for quality, delivery, and documentation.
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Powerful Factory Capacity
1200+ tons monthly output across flanges, elbows, tees, reducers, and MCI fittings.
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QA / QC Under Control
ISO 9001 quality system, PMI testing, hydrostatic pressure testing, and 100% dimensional inspection.
🎨
OEM/ODM Design
Custom facing, thread types, nipple lengths, and coatings. From drawing to container in 4–6 weeks.
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High-Speed Delivery
15–30 days for standard items. Air-freight or consolidated ocean shipping to any major port.
📈 One-Stop Pipe & Fittings Supply
Beyond flanges, we supply steel pipes, three-way tees, pipe elbows, reducers, and malleable cast iron (MCI) fittings. That means one PO, one inspection, one shipment — reducing your procurement overhead and logistics complexity.
→ Compare your current MTO with our bundled flange + pipe quote
📐 Technical Data: Unthreaded Pipe Flange & Flange with Threaded Nipple
Below is the core specification matrix for our two flagship connection products. These values are directly citable in your engineering datasheets and supplier approval documents.
| Parameter | Unthreaded Pipe Flange (Slip-On) | Flange with Threaded Nipple |
|---|---|---|
| Design Standard | ASME B16.5, ASME B16.47, EN 1092-1, DIN 2576/2633, JIS B2220 | ASME B16.5 (flange) + ASME B1.20.1 / ISO 7-1 (threads) |
| Material Grades | ASTM A105, A105N, A350 LF2, ASTM A182 F304/L, F316/L, Alloy 20, Hastelloy C276 | Malleable cast iron (MCI), ASTM A105, ASTM A182 F304/F316, cast iron per ASTM A126 |
| Nominal Bore (DN) | DN15 – DN600 (1/2" – 24") | DN15 – DN100 (1/2" – 4") standard; custom to DN150 |
| Pressure Class | 150# – 600# (PN16 – PN100); custom to 900# | 150# – 300# (PN16 – PN40) typical for threaded service |
| Facing Types | RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint) | RF (Raised Face), FF (Flat Face) |
| Thread Types | N/A (welded to pipe) | NPT, NPTF, BSPT (R), BSPP (G), Metric (M) |
| Nipple Length | N/A | Standard 50mm / 80mm / 100mm; OEM custom 20–300mm |
| Surface Treatment | Black oil, zinc epoxy, hot-dip galvanized, PTFE coating | Hot-dip galvanized, electro-galvanized, black phosphating, zinc-nickel |
| Certifications | ISO 9001, CE/PED, EN 10204 3.1 MTC, PMI report | ISO 9001, CE/PED, UL Listed (MCI options), EN 10204 3.1 |
→ Download our full material test certificate (MTC) sample
🔩 Unthreaded Pipe Flange: The Reliable Workhorse of Low-to-Medium Pressure Piping
The unthreaded pipe flange — commonly specified as a slip-on flange — slides over the pipe bore and is secured via fillet welds at both the hub and the back. Because there are no threads, it allows for easier alignment in the field: the fitter can rotate the flange to match the bolt holes before welding, which dramatically reduces installation time.
From a cost perspective, the slip-on flange is 10–20% more economical than a weld-neck flange in the same pressure class, while still offering excellent leak integrity for services up to 600#. Material options run from ASTM A105 carbon steel for general refinery use, to F316/L stainless for chemical, pharmaceutical, and offshore corrosive environments.
Key engineering note: In cyclic or thermal-fatigue applications, the fillet weld at the flange hub creates a localized stress concentration. Design engineers should evaluate the ASME B31.3 flexibility limit and account for the stress intensification factor (SIF) if the system undergoes >7,000 full thermal cycles.
CNC flange facing & drilling line
📏 Unthreaded Pipe Flange — Dimensional Reference (ASME B16.5, 150# RF)
Typical dimensions for design engineers:
| DN (inch) | OD (mm) | Bore (mm) | Thickness (mm) | No. Bolts |
|---|---|---|---|---|
| 1/2" (DN15) | 88.9 | 22.4 | 11.2 | 4 |
| 2" (DN50) | 152.4 | 59.2 | 19.1 | 4 |
| 6" (DN150) | 279.4 | 154.2 | 25.4 | 8 |
| 12" (DN300) | 444.5 | 303.2 | 31.8 | 12 |
→ Need a full BN(B16.5) dimension chart? Request it in 30 seconds
Threaded nipple assembly & galvanizing line
🔗 Flange with Threaded Nipple: Weld-Free Connection for Speed & Safety
A flange with threaded nipple combines a forged flange and a precision-cut threaded pipe nipple into a single pre-assembled unit. This product is a game-changer for applications where hot work (welding) is prohibited — such as on-site installation in explosive atmospheres, offshore platforms, existing pipeline retrofits, or facilities with strict fire-safety permits.
The threaded nipple is manufactured to ASME B1.20.1 (NPT) or ISO 7-1 (BSPT) tolerances, with taper thread profile verified by laser contour measurement and ring-gauge inspection. The flange-to-nipple connection is sealed via a metal-to-metal tapered thread interference fit, capable of maintaining leak-tightness at rated pressure without sealant — although PTFE tape or anaerobic sealant is recommended for repeat disassembly cycles.
Why buyers choose this: Installation is 60–70% faster than welded flanges. Every unit is hydro-tested to 1.5× the rated pressure before leaving our factory.
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60% Faster Install
No welding, no NDT wait. Thread on and torque to spec.
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Explosion-Safe
Zero hot work — ideal for hazardous area installations.
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Easy Maintenance
Disassemble and reassemble without destroying the joint.
→ Get torque specs and thread sealant recommendations for your service
📊 Engineering Data & Research Behind Flange Reliability
We believe every component we ship should be backed by verifiable mechanical data. Here is how the current literature supports our design and material choices:
🔬 Bolted Flange Joint Dynamics
Simplified Nonlinear Dynamic Model for Pipe Structures with Bolted Flange Joints (Luan, Guan, Cheng & Liu, Journal of Sound and Vibration, 2012) established reduced-order models for flange joints under nonlinear contact. The implication for us: gasket seating stress and bolt preload consistency directly impact system dynamic stability. That is why we torque-test every threaded nipple flange assembly before logistics.
⚙️ Rigid Flange Material Selection
The 2025 paper Performance Material Selection in Rigid Flange Coupling Systems (Cureus Journal of Engineering) provides a decision matrix balancing mechanical strength, corrosion resistance, and cost. We apply this same logic: for saltwater exposure, we push 316L or duplex over carbon steel + coating; for high-temperature hydrocarbon service, we select A105 or F11 based on the ASME B16.5 pressure-temperature derating curves.
📐 Tee & Elbow Stress Indices
Per the Reference Stress Method for Defective Elbows – R6 FAD Assessment and the Sustained Stress Indices at Tee Connections literature (available on ScienceDirect and Academia.edu), stress intensification factors (SIF) at pipe branch connections are often underestimated. While our flanges are not elbows or tees, the same principle applies to the flange-to-pipe transition zone in unthreaded pipe flanges — an unground fillet weld can create a SIF of 2.1× nominal stress. Our quality manual mandates smooth transition grinding for cyclic service.
Practical engineering takeaway: When selecting between an unthreaded pipe flange and a flange with threaded nipple, consider fatigue and thermal cycling. The threaded variant introduces a thread root stress concentration (~2.5–3× theoretical), so for severe cyclic duty above 2,000 cycles, ASTM F1545 or an unthreaded design with backing weld is recommended.
→ Request our flange stress calculation worksheet for your next project
🏗️ Application Scenarios & Select Case Studies
Both product lines serve mission-critical roles in industrial piping networks. Here is where they are used most effectively:
⛽
Oil & Gas / Refinery
Unthreaded pipe flanges in A105 and F316L for crude transfer lines, cooling water, and firewater loops. Rated to 600# with RTJ facing for critical hydrocarbon service. Case study: A Kazakhstan oilfield operator cut flange procurement costs by 31% after switching to our factory-direct supply.
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Water & Wastewater Treatment
Flange with threaded nipple (MCI and 316L) for chemical dosing lines, filter manifolds, and air-scour piping. Hot-dip galvanized exterior minimizes above-ground corrosion. A Canadian water utility achieved a 4-year zero-leak record on our MCI threaded flanges.
⚡
Fire Protection / Sprinkler Systems
UL-listed malleable iron flanges with threaded nipple to NFPA 13. No welding on sprinkler risers means faster inspection and lower construction labor. A Middle East contractor reported a 22% reduction in installation hours using our pre-assembled units.
🔬
Pharmaceutical & Food Processing
Stainless steel unthreaded flanges with PTFE gasket surfaces for sanitary process lines. Surface roughness ≤ 0.8 µm Ra on demand. US-based pharma OEM uses our F316L flanges in CIP/SIP systems with zero product contamination reports.
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HVAC & District Energy
Threaded nipple flanges enable rapid tie-ins to existing steel pipe systems without shutting down the entire loop. District heating operators in Northern Europe value the simplicity and lower skilled-labor requirements of threaded assemblies.
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Shipbuilding & Offshore
ABS/DNV-approved material grades available. Flange with threaded nipple is a preferred choice for ballast line modifications where hot work permits are constrained. A Singapore shipyard standardized on our threaded assemblies for 3 retrofit projects.
→ Tell us your application — receive 3 applicable case studies
🛠️ From Raw Steel to Export-Ready Crate: Our Manufacturing Flow
Step 1: Material inbound — ASTM A105/A182 verification with mill certificate traceability.
Step 2: Forging or casting (MCI) — controlled temperature and pressure cycles.
Step 3: Heat treatment — normalizing / annealing per API 20B or ASME requirements.
Step 4: Machining — CNC lathe flange facing, boring, and drilling to ASME B16.5 tolerances.
Step 5: Threading (for threaded nipple flange) — CNC thread milling + ring gauge inspection for NPT/BSPT.
Step 6: Weld assembly (for unthreaded flange) — TIG root + MIG fill, 100% visual + optional dye-penetrant testing.
Step 7: Surface treatment — galvanizing, epoxy, PTFE, or black oil per customer spec.
Step 8: Final QC — dimensional, pressure, PMI, and coating thickness reports.
Step 9: Export packing — plywood crates or steel pallets with desiccant and VCI anti-rust film.
QA commitment: We perform hydrostatic pressure testing at 1.5× rated pressure on every flange with threaded nipple. Unthreaded flanges undergo 100% dimensional inspection with CMM for bolt-circle accuracy. MTCs are issued in accordance with EN 10204 Type 3.1.
→ Watch our 2-minute QC video tour (or request a live virtual factory inspection)
🤝 Trusted by Industrial Buyers Across 20+ Countries
SiemensBoschGEAccentureShenhua
★★★★★
“We sourced 1,200 units of unthreaded pipe flanges (A105, 300#) for a Canadian water treatment upgrade. The MTC documentation was spotless, and every flange matched ASME tolerances. No rework.”
Mike R.
Procurement Lead, Ontario Utility
★★★★★
“Their flange with threaded nipple solved our offshore hot-work bans. Installation crew finished ballast line tie-ins in 3 days instead of 2 weeks. Huge safety win.”
James T.
Projects Director, Singapore Shipyard
★★★★★
“We ran an A/B comparison between Cangzhou Weihuan and our previous European supplier. Same spec, 27% lower total landed cost. Now we just reorder from their catalog.”
Sara K.
Operations Manager, Germany
💬 Live from Our Client Inquiries
❓ Frequently Asked Questions — Unthreaded Pipe Flange & Flange with Threaded Nipple
📌 What is the difference between an unthreaded pipe flange and a flange with threaded nipple?
An unthreaded pipe flange (slip-on flange) has a smooth bore that slides over the pipe and is secured by fillet welds. A flange with threaded nipple has a threaded pipe nipple already attached via NPT/BSPT threads, so it can be screwed directly onto a threaded pipe end without welding. Choose unthreaded for higher pressure/cyclic duty; choose threaded nipple for speed, safety, and zero hot work.
📌 What materials are available for your flanges?
We offer ASTM A105, A105N, A350 LF2 (carbon steel), ASTM A182 F304, F304L, F316, F316L (stainless steel), and specialty alloys such as Alloy 20 and Hastelloy C276 on request. For threaded nipple flanges, we additionally offer malleable cast iron (MCI) per ASTM A197 and cast iron per ASTM A126.
📌 What thread standards do you support for threaded nipple flanges?
We machine threads to ASME B1.20.1 (NPT/NPTF), ISO 7-1 (BSPT), BSPP (G), and metric thread profiles. Each unit is verified with calibrated ring and plug gauges. For critical services, we can add thread laser contour scanning and dye penetrant inspection.
📌 What is your minimum order quantity (MOQ) and lead time?
Our MOQ is 50 pieces for standard unthreaded pipe flanges and 100 pieces for flange with threaded nipple assemblies. Standard lead time is 15–25 days after sample approval; expedited air-freight options can reduce this to 7–10 days. For special alloys or OEM custom dimensions, lead time may extend to 30–35 days.
📌 Can you provide EN 10204 3.1 material certificates and PMI reports?
Yes. Every order ships with EN 10204 Type 3.1 material test certificates as standard. PMI (Positive Material Identification) testing using XRF analyzers is available as a mandatory step for stainless and alloy grades. We can also arrange third-party inspection by SGS, BV, or Intertek at your cost.
📌 What is the cost difference between unthreaded pipe flange and flange with threaded nipple?
In the same material and pressure class, a flange with threaded nipple typically costs 15–25% more than a bare unthreaded pipe flange due to the additional threading, assembly, and hydrostatic testing. However, if your project is in a no-hot-work zone, the threaded assembly will save you far more in installation labor, permitting fees, and schedule acceleration.
📌 How do you handle shipping for large flange orders?
We consolidate orders to optimize freight. For full container loads (FCL), we load directly at our factory in Hebei Province. For LCL, we offer consolidated shipments to major ports (Houston, Rotterdam, Antwerp, Jebel Ali, etc.). Our logistics team provides a door-to-door DDP quotation so you can compare true landed cost with your current supplier.
📌 Can you produce custom nipple lengths and special coatings?
Absolutely. Our OEM/ODM capability covers custom nipple lengths from 20mm to 300mm, special facing finish (125–250 AU), PTFE liners, galvanized coatings, and custom paint colors. Just send your drawing or sample, and our engineering team will provide a detailed drawing for approval before mass production.
Ready to Request a Quote?
Send us your specification list — we will respond within 24 hours with pricing, lead time, and technical documentation.
💬 What Our Customers Say
★★★★★
“We ordered 800 flange with threaded nipple assemblies for an industrial firewater upgrade. The machining quality was excellent — every thread gauge-clean. The galvanized finish was uniform and free of drips. Highly recommend for value and reliability.”
Robert H.
Fire Protection Contractor, Texas, USA
★★★★★
“Very responsive team. They provided EN 10204 3.1 certificates, PMI reports, and hydrostatic test data before we even confirmed the PO. Our QA department was impressed by the documentation quality.”
Fatima A.
QA/QC Manager, UAE
★★★★★
“We compared quotations from four Chinese suppliers. Cangzhou Weihuan gave us the most complete spec sheet, the fastest sample delivery, and the clearest Incoterms. We placed a $180,000 annual contract for unthreaded pipe flanges.”
Oleg P.
Supply Chain Manager, Kazakhstan
About the Author
David Liang — Senior Pipeline Fittings Engineer & Industry Analyst
David has spent 14 years in the steel pipe & fittings industry, leading technical sales and quality teams at Cangzhou Weihuan Pipeline Equipment Co., Ltd. He is a certified welding inspector (CWI) and has contributed to flange connection design reviews for oil & gas, water, and fire protection projects in North America, Europe, and the Middle East. His articles on piping component selection have been referenced by engineering consultancies and procurement teams in 6 countries.
Cangzhou Weihuan Pipeline Equipment Co., Ltd. · Member: ASTM International · ASME B16.5 standards committee observer
🚀 Get Your Factory-Direct Quote in 24 Hours
Send your flange specifications, Bill of Materials, or drawing today. Our engineering sales team will respond with precise pricing, lead time, and compliance documentation — no obligations, no middlemen.
⏰ Limited-Time: 5% Off First Order for New Buyers (Q3 2026)·🔄 Free Replacement for Any Non-Compliant Parts·📦 Free Sample for Qualified Projects
© 2026 Cangzhou Weihuan Pipeline Equipment Co., Ltd. · Address: Middle section of National Highway 338, Mengcun Hui Autonomous County, Cangzhou City, Hebei Province, China
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