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Views: 0 Author: Site Editor Publish Time: 2026-10-19 Origin: Site
Weld Neck vs Slip On Flange: Differences & Application Guide
Compare weld neck vs slip on flanges: structure, pressure rating, welding performance and application scenarios. Choose the right flange for your industrial piping project.
Proper flange selection directly determines the sealing stability and service life of the entire piping system. Wrong flange type may cause leakage under high pressure, temperature fluctuation or pipeline vibration, bringing safety hazards and extra maintenance costs. Weld Neck Flange (WN) and Slip On Flange (SO) are two of the most widely used flanges in industrial piping. Many buyers are confused about which one fits their project. This guide breaks down their structural features, performance gaps and suitable working conditions to help you make an accurate selection.
WN flange comes with an integrated tapered hub (high neck). The hub gradually transitions stress to the pipe wall. It adopts butt welding at the pipe end. Full penetration weld connects flange and pipe, achieving uniform stress distribution. The long neck design greatly reduces stress concentration at the welding joint.
SO flange has no high neck. The pipe slips through the flange inner bore before welding. It uses fillet welding on both front and back sides of the flange face. Simple flat structure, no tapered transition hub. The weld only bears partial load, and stress concentration is more obvious at the joint.
表格
Item | Weld Neck Flange (WN) | Slip On Flange (SO) |
|---|---|---|
Pressure Rating | Higher, suitable for high-pressure piping | Medium & low pressure only |
Temperature Resistance | Excellent, stable under high & fluctuating temperature | Good for normal temperature, limited for extreme thermal cycling |
Welding Strength | Butt weld, full penetration, high joint integrity | Double fillet weld, lower weld strength |
Installation Difficulty | Higher, need pipe end bevel & alignment, more welding work | Simple, easy alignment, fast installation |
Cost | Higher | Lower |
Applicable Pipe Size | Wide range, large diameter & heavy wall pipe available | Mostly for small & medium diameter pipes |
Petrochemical & Oil & Gas: WN flange is preferred. It handles high pressure, high temperature and pipeline vibration, widely used in process pipelines, refinery and offshore piping. SO flange is only used for auxiliary low-pressure pipelines.
Power Industry: High-temperature steam pipeline adopts WN flange for reliable sealing. SO flanges apply to low-pressure auxiliary water pipelines.
Water Supply & Drainage: SO flange dominates low-pressure water, sewage pipelines for cost saving. WN is selected when water system has high pressure or water hammer risk.
General Industry & Factory Utilities: SO flanges are common for compressed air, low-pressure liquid pipelines. WN flanges for critical process lines with pressure shock.
Step1: Confirm working condition — High pressure / high temperature / heavy vibration? ✅ Choose WN. Low pressure & normal temperature? Go to Step2. Step2: Check media risk — Hazardous, flammable or toxic fluid? ✅ Choose WN. Clean non-hazardous medium? Go to Step3. Step3: Budget & maintenance requirement — If budget is limited and pipeline rarely disassembles, select SO; for critical lines requiring long-term safety, pick WN.
Using SO flange on high-pressure process piping: Fillet weld may crack under pressure shock, resulting in medium leakage.
Replacing WN with SO to cut cost in toxic media pipeline: Leakage will cause safety accident.
Neglecting pipe wall thickness for WN butt weld: Improper bevel leads to incomplete penetration and hidden welding defect.
Overlooking pipeline thermal expansion: SO joints are vulnerable under cyclic thermal stress.
We are a source manufacturer of stainless steel and alloy flanges. Our product range covers WN, SO, BL, TH, LJ flanges in 304, 316L, 2535, Inconel and other materials, complying with ASME B16.5, EN, GB standards. Send your piping parameters, pressure class and drawing to us. Our engineering team provides free technical suggestion and quotation for your flange project.
FAQ:
1:How long is the custom lead time for stainless steel flanges in Wenzhou?
— 8 to 10 working days
2:What is the fastest delivery time?
— 3 working days
3:Do you support non-standard custom flanges?
— Yes, we do.
4:Can you process special sizes?
— Yes. Max processing size: 4000 mm, Min processing size: 30 mm.
5:Do you have stainless steel flanges of standard sizes in stock?
— Yes.
6:Can we customize flanges based on customer drawings or samples?
— Yes.
7:Will material test certificates and inspection reports be provided for the purchased flanges?
— Yes, they will.
8:Is there a quality warranty for the flange products?
— Yes.
9:How to handle quality defects if they occur?
— Product return and exchange available.
