Slip On Flange Manufacturer in India | SO / SORF / SOFF | ASME B16.5 | Remax Forge
Key Features
Slides over pipe — easy installation
Bore is slightly larger than pipe OD allowing the pipe to slide freely before both fillet welds are applied.
Double fillet welded — inside & outside
Inner weld prevents fluid penetration; outer weld provides structural strength. Two welds per ASME code.
Cost-effective for general service
Strength = 2/3 of Weld Neck. Ideal for low-to-medium pressure water, steam, and chemical lines.
What is a Slip On Flange?
A Slip-On Flange (SO Flange) slides over the pipe and is secured by two fillet welds — one executed on the inside bore (to prevent fluid penetrating between pipe and flange) and one on the outside. The flange bore is slightly larger than the pipe OD to allow the pipe to slide freely before welding.
Industry Abbreviations
Key Technical Facts Buyers Need to Know:
- Strength under internal pressure = 2/3 of Weld Neck Flange
- Fatigue life ≈ 1/3 of Weld Neck Flange
- NOT recommended for cyclic, high-vibration, or high-pressure services
- Two weld zones create two potential leak paths (vs one for Weld Neck)
- Available as forged (with hub) or fabricated from plate (no hub)
- The "hub" version has a short raised section that improves stress distribution
- Easy to install — pipe doesn't need precise cut length; slide and weld
- More economical than Weld Neck for non-critical services
🔗 For high-pressure, cyclic, or critical service, see our Weld Neck Flange. Compare our complete flange range for your project.
Standard Specifications
Remax Forge & Fittings manufactures forged Slip On Flanges to meet stringent international standards. The table below answers the five most common buyer questions in one place:
| Property | Detail |
|---|---|
| Product Names | Slip On Flange, SO Flange, SORF, SOFF, Hubbed Flange |
| Size Range | ½" (15 NB) to 48" (1200 NB); larger on custom order |
| Pressure Classes | 150#, 300#, 400#, 600#, 900#, 1500#, 2500# (ASME B16.5); PN6, PN10, PN16, PN25, PN40, PN64 (DIN/EN) |
| Face Types | RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint), T&G (Tongue & Groove), M&F (Male & Female) |
| Standards | ANSI/ASME B16.5, B16.47 Series A & B, BS 4504, BS 10 Table D/E, EN 1092-1, DIN 86029, JIS B2220, MSS SP-44, AWWA C207, GOST, API 605 |
| Material Forms | Forged (with hub) or Fabricated from plate (no hub) |
| MTC | EN 10204 3.1 standard; 3.2 on request; NACE MR0175/MR0103 available |
| Coating | Anti-rust paint, oil paint, zinc plated, hot-dip galvanized |
| Origin | India (Mumbai) / USA / Japan / Europe / Korea |
| Lead Time | 7–14 days (standard); 3–6 weeks (special alloy/custom) |
Slip On Flange Material Grades
We forge industrial Slip On Flanges in a wide variety of metallic materials to handle diverse chemical and corrosion requirements. Our range includes high-integrity Stainless Steel, Duplex Steel, Super Duplex Steel, low temperature Carbon Steel (LTCS), high yield Carbon Steel, Alloy Steel, and corrosion-resistant Nickel Alloys (Inconel, Hastelloy, Monel):
| Material Category | Grades / Specifications |
|---|---|
| Stainless Steel Slip On Flanges | ASTM/ASME A/SA182: F304, F304L, F316, F316L, F316H, F316Ti, F321, F347; Cast: CF3, CF3M, CF8, CF8M; DIN: 1.4301, 1.4306, 1.4401, 1.4404, 1.4408, 1.4409 |
| Duplex Steel Slip On Flanges | UNS S31803/S32205 — ASTM A182 Gr F51, F52, F53, F54, F55, F57, F59, F60, F61 |
| Super Duplex Slip On Flanges | UNS S32750/S32760 — ASTM A182 Gr F53, F55; Zeron 100 |
| Carbon Steel Slip On Flanges | ASTM/ASME A/SA105, A105N, A216-WCB; A350 LF2 (low temp); A694 F52/F56/F60/F65/F70/F80 (high yield); DIN 1.0460, 1.0402, 1.0619 |
| Alloy Steel Slip On Flanges | ASTM A182/ASME SA182: F5, F9, F11, F12, F22, F91 (all P-grades for high temp service) |
| Nickel Alloy Slip On Flanges | Inconel 600, 601, 625, 718, 690, X750 (ASTM B564/ASME SB564); Incoloy 800, 800H, 800HT, 825, 925 |
| Hastelloy Slip On Flanges | C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X (ASTM B564) |
| Monel Slip On Flanges | Monel 400 (UNS N04400), Monel K500 (UNS N05500) — ASTM B564 |
| Pure Nickel Slip On Flanges | Nickel 200, 201, 205, 205LC — ASTM B564/ASME SB564 |
| Copper Nickel Slip On Flanges | CuNi 90/10 (C70600), CuNi 70/30 (C71500), UNS C71640 — ASTM/ASME SB 61/62/151/152 |
| Titanium Slip On Flanges | Gr.1, Gr.2, Gr.4, Gr.5, Gr.7 — ASTM B381/ASME SB381; R50250/R50400/R50550/R50700/R52400/R53400/R56400 |
| Aluminium Slip On Flanges | 5052, 6061, 6063, 2017, 7075 |
| Brass Slip On Flanges | 3602, 2604, H59, H62 |
| Special Alloy Slip On Flanges | Alloy 20 (ASTM B462 SB462 — Carpenter 20Cb-3); SMO 254/6Mo (UNS S31254, DIN 1.4547); Al6XN; AISI 4130; AISI 4140; Nimonic 75/80A/90; Gunmetal; Cast Iron |
Forged Raw Billets stockSlip On Flange Standards & Specifications
Our forged Slip On Flanges are engineered according to ASME, ANSI, DIN, EN, JIS, and BS standards. We also offer customization to client-specific drawings and dimensional schedules:
| Standard / Spec | Scope / Application Details |
|---|---|
| 🇺🇸ANSI/ASME B16.5 | NPS ½" to 24" — the primary standard for most flanges |
| 🇺🇸ASME B16.47 Series A (MSS SP-44) | NPS 26" to 60" — large diameter |
| 🇺🇸ASME B16.47 Series B (API 605) | NPS 26" to 60" — large diameter (lighter) |
| 🇺🇸ASME B16.36 | Orifice flanges |
| 🇺🇸ASME B16.48 | Line blinds & spectacle blinds |
| 🇪🇺DIN 2501 / EN 1092-1 | European metric standard — PN ratings |
| 🇯🇵JIS B2220 | Japanese Industrial Standard |
| 🇬🇧BS 4504 / BS 10 Table D/E/F/H | British Standard |
| 🇺🇸MSS SP-44 | Large diameter steel pipeline flanges |
| 🇺🇸API 6A | Wellhead and Christmas tree equipment |
| 🇺🇸API 605 | Large diameter carbon steel flanges |
| 🇺🇸AWWA C207 | Water works flanges |
| 🇷🇺GOST 12820 / 12821 | Russian/CIS standard |
| 🇦🇺AS 2129 / AS 4087 / AS/NZS 4331.1 | Australian standard |
| 🇰🇷KS B1503 | Korean standard |
| 🌐ISO 7005-1 / ISO 9624 | International standard |
| 🇺🇸SAE J518 | Hydraulic flanged tube fittings |
| 🇨🇳GB Standard | Chinese national standard |
ASME B16.5 Slip On Flange Dimensions Table
Review our detailed dimensional chart for Class 150# forged Slip On Flanges. Dimensions per ASME B16.5. Weights are approximate for Carbon Steel A105. Click column headers to sort:
Contact us for exact drawings, Class 300# dimensions, or downloadable PDF catalogue.
NPS (inch)↕ | DN (mm)↕ | Flange OD (mm)↕ | Bolt Circle (mm)↕ | No. of Bolt Holes↕ | Bolt Hole Dia (mm)↕ | Flange Thickness T (mm)↕ | Hub OD (mm)↕ | Approx. Weight CS (kg)↕ |
|---|---|---|---|---|---|---|---|---|
| ½ | 15 | 89 | 60 | 4 | 16 | 9.6 | 35 | 0.4 |
| ¾ | 20 | 98 | 70 | 4 | 16 | 11.2 | 43 | 0.5 |
| 1 | 25 | 108 | 79 | 4 | 16 | 12.7 | 51 | 0.7 |
| 1¼ | 32 | 117 | 89 | 4 | 16 | 14.3 | 64 | 0.9 |
| 1½ | 40 | 127 | 98 | 4 | 16 | 15.9 | 73 | 1.1 |
| 2 | 50 | 152 | 121 | 4 | 19 | 17.5 | 92 | 1.6 |
| 2½ | 65 | 178 | 140 | 4 | 19 | 20.6 | 105 | 2.4 |
| 3 | 80 | 190 | 152 | 4 | 19 | 23.9 | 127 | 3.0 |
| 4 | 100 | 229 | 190 | 8 | 19 | 23.9 | 157 | 4.5 |
| 6 | 150 | 279 | 241 | 8 | 22 | 25.4 | 216 | 7.5 |
| 8 | 200 | 343 | 298 | 8 | 22 | 28.6 | 270 | 12.0 |
| 10 | 250 | 406 | 362 | 12 | 25 | 30.2 | 324 | 18.5 |
| 12 | 300 | 483 | 432 | 12 | 25 | 31.8 | 381 | 27.0 |
| 14 | 350 | 533 | 476 | 12 | 29 | 35.1 | 413 | 34.0 |
| 16 | 400 | 597 | 540 | 16 | 29 | 36.6 | 470 | 45.0 |
| 18 | 450 | 635 | 578 | 16 | 32 | 39.7 | 533 | 58.0 |
| 20 | 500 | 699 | 635 | 20 | 32 | 42.9 | 584 | 72.0 |
| 24 | 600 | 813 | 749 | 20 | 35 | 47.8 | 692 | 104.0 |
* Dimensions per ASME B16.5. Weights are approximate for Carbon Steel A105. Contact us for Class 300# and higher class dimension tables.
Flange Face Types
Remax Forge & Fittings manufactures Slip On Flanges in several face type designs — RF (Raised Face), FF (Flat Face), RTJ (Ring Type Joint), T&G (Tongue & Groove), and M&F (Male & Female) — to accommodate different sealing gaskets and pressure ratings.
Raised Face (RF)
Most common. A raised circular ring that concentrates pressure on a smaller area to compress the gasket. Height: 1/16" for Class 150/300; 1/4" for Class 400 and above.
Flat Face (FF)
No raised portion; entire flange face is in the same plane. Used when mating against cast iron or non-metallic flanges to avoid cracking on bolt tightening.
Ring Type Joint (RTJ)
Oval or octagonal groove machined into the face; a metal ring gasket seats in the groove. Used in high-pressure, high-temperature critical service (refineries, oil fields).
Tongue & Groove (T&G)
One flange has a raised ring (tongue); the other a matching groove. Provides excellent alignment and a confined gasket. Used in pumps and valve bonnets.
Male & Female (M&F)
Similar to T&G but the female face is flat and the male face raised. Used in heat exchangers, pressure vessels, and high-integrity process joints.
Large Male & Female
Same operating principle as the standard Male & Female flange, scaled up with larger step contact surfaces for specialized heavy industrial equipment.
Advantages & Limitations of Slip On Flange
✅ Advantages
Lower Cost
Less material and machining vs Weld Neck; ideal for budget-sensitive projects.
Easy Installation
Pipe doesn't need precise cut length — just slide in and weld.
Easier Alignment
Pipe can be repositioned slightly before tack welding for perfect fit.
Faster Fabrication
Two fillet welds are faster to execute than a full-penetration butt weld.
Low/Medium Pressure Service
Perfect for water, steam, and general process piping at moderate pressures.
Wide Availability
Stocked in all common sizes and materials with 7–14 day lead times.
Limitations — Transparent Disclosure
We believe informed buyers make better decisions. Here are the technical limitations of Slip On Flanges — this is why Weld Neck Flanges exist for critical services:
Industries & Applications
✓Primary Applications
- General process piping (water, air, steam at moderate pressures)
- Chemical supply lines (non-critical, non-corrosive)
- HVAC systems
- Fire suppression systems
- Municipal water and wastewater treatment
- Cooling water systems
- Pharmaceutical utilities (CIP/SIP water)
- Food and beverage (non-aseptic service)
- Agricultural irrigation systems
- Shipbuilding ballast and bilge lines
✗NOT Recommended For
💡 For the above services, consider our Weld Neck Flange which offers full pressure rating and superior fatigue life.
Oil & Gas
Upstream extraction, midstream pipelines, downstream refineries.
Petrochemical
Chemical reactors, process lines, heat exchangers.
Power Generation
Boilers, steam turbines, nuclear plants, thermal power.
Pharmaceuticals
Hygienic piping, clean steam, pure water systems.
Food & Beverage
Sanitary flanges, sugar mills, beverage processing.
Paper & Pulp
Chemical recovery, bleaching lines.
Water Treatment
Municipal water, desalination, irrigation.
Shipbuilding
Offshore platforms, FPSOs, marine piping.
Chemical Plants
Acid service, caustic lines, solvent handling.
Construction
HVAC, fire suppression, utility headers.
Testing & Inspection
We implement a rigorous, zero-defect quality control protocol on all flange fabrications. Every single production batch undergoes strict visual inspection and dimensional checking. In addition, we offer advanced non-destructive testing (NDT) such as ultrasonic testing, positive material identification (PMI) spectrometer analysis, hydrostatic pressure testing, and magnetic particle examinations.
Hydrostatic / Hydro Pressure Test
Each flange pressure tested at 1.5x working pressure per ASME code requirements.
Ultrasonic Testing (UT)
Non-destructive testing to detect internal sub-surface cracks, inclusions and forging defects.
Radiographic Testing (RT / X-Ray)
100% radiography available; mandatory for critical Class 900+ high pressure services.
Positive Material Identification (PMI)
Spectrometer validation to verify alloy chemistry precisely matches the Mill Test Certificate.
Dye Penetrant Test (DPT / LPT)
Detects micro surface cracking and porosity on critical machined seating surfaces.
Magnetic Particle Inspection (MPI)
For ferromagnetic alloys; flags surface and near-surface structural discontinuities.
Hardness Test (Brinell/Rockwell)
Verifies correct heat treatment structure and ensures mechanical properties are hit.
Direct-Reading Spectrograph
In-house lab chemical checks of billets before forging process begins.
Impact / Charpy Test
Crucial for low-temperature applications to verify ductility (e.g. A350 LF2, LTCS).
NACE Compliance Testing
Verifies sour-gas / H2S environment service capability (NACE MR0175 / MR0103).
Documents & Certificates
Traceability and quality assurance are integral to our manufacturing process. We supply a comprehensive package of documentation with every shipment at no extra cost, including Mill Test Certificates (MTC) in accordance with EN 10204 3.1. Third-party inspection clearances from SGS, Lloyd's, and DNV available on request.
Mill Test Certificate (MTC)
Provided as per EN 10204 3.1 detailing chemical & mechanical analysis.
EN 10204 3.2 Certificate
Independent third-party inspection validation (available upon request).
NACE MR0175 / MR0103 Compliance
Certified suitability for sour gas/H2S environments.
Raw Materials Certificate
Provides 100% trace origin tracking from steel billet to finished flange.
Dimensional Inspection Report
All critical tolerances checked and certified against CAD designs.
Heat Treatment Certificate
HTR and PWHT thermal chart records included where requested.
Hydrostatic Test Certificate
Pressure log documentation verifying weld integrity.
Third Party Inspection (TPI)
Bureau Veritas, SGS, Lloyds, DNV, TUV inspection options.
Packing List & Weight Certificate
Proper documentation for simple custom clearance and cargo log.
Country of Origin Certificate
Enables import tariff relief and compliance logging.
Slip On Flange vs Other Flange Types
Not sure which flange is right for your project? Use this quick comparison to decide:
| Feature | Slip On Flange | Weld Neck Flange | Socket Weld Flange |
|---|---|---|---|
| Weld Joints Required | 2 fillet welds | 1 butt weld (full penetration) | 1 fillet weld (external only) |
| Pressure Rating | Medium (up to 600# preferred) | Highest (all classes) | High (½"–3" small bore) |
| Installation Speed | Faster | Slower (precise bore match) | Moderate |
| Cost (Relative) | Lowest | Highest | Moderate |
| Fatigue Life | ~1/3 of Weld Neck | Highest | ~2/3 of Weld Neck |
| Size Range | ½" to 48" (custom) | ½" to 60" | ½" to 3" (standard) |
| Radiography | Not feasible (fillet weld) | 100% RT capable | Not feasible |
| Best For | General/moderate service | Critical/high pressure | Small-bore high pressure |
Surface Finish & Coating Options
Anti-rust Paint
Standard protection coat applied on carbon steel flanges.
Oil Black Paint
High-grade finish offering superior long-term storage corrosion block.
Yellow Transparent Lacquer
Allows technical inspectors to visually inspect metal surface during receiving.
Zinc Plated
Electro-galvanized bright zinc barrier layer for light industrial environments.
Hot Dip Galvanized (HDG)
Thick zinc alloy barrier layer for maximum outdoor marine rust protection.
Epoxy Coating
FBE or liquid epoxy coating for heavy buried pipelines and sewage lines.
Bare/Pickled & Passivated
Chemical acid cleaning to restore corrosion resistance for stainless steel.
Custom Coating
Special finishes customized exactly to customer painting specifications.
Export Markets
Global Export Network
Why Choose Remax Forge?
Remax Forge & Fittings stands out as a leading flange manufacturer due to our complete in-house forging, heat treatment, and precision CNC machining capabilities based in Mumbai. We provide certified compliance, factory-direct wholesale pricing, and custom forging schedules tailored to your engineering blueprints. With over 20 years of manufacturing experience, zero-defect quality management, and short lead times, we are a trusted supply partner for critical industrial piping projects.
ISO 9001:2015 Certified
Fully audited quality management workflows.
In-House Forging
Forging, heat-treat, machining in Mumbai.
Testing Laboratory
PMI, Spectro, UT, Hydro labs on-site.
Mill Certificates
EN 10204 3.1 standard; 3.2 available.
20+ Years Experience
Serving critical gas/oil clients globally.
45+ Export Countries
Proven global logistics and documentation.
Custom Forging
Special shapes, alloys and schedules.
Factory-Direct Price
Competitive pricing with no agent markup.
Technical Support
Engineers ready to assist spec selection.
Short Lead Times
Fast turnaround of custom and stock orders.
📥 Download Slip On Flange Catalogue (PDF)
Get the complete technical catalogue including product description, full ASME B16.5 Class 150# & 300# dimension tables, material grades, standards, and weight charts — ready to share with your team or attach to your RFQ.
How to Order
Ordering high-quality forged flanges from Remax is straightforward. To ensure our engineering team provides you with a precise and competitive quote, please specify the exact flange type, nominal pipe size (NPS), pressure class rating, material grade, and facing configuration. Let us know your total quantity requirements and if you require any specialized testing or custom coatings. Contact us via email or phone for a quick, same-day response.
Direct Inquiries
Estimated Lead Times
Frequently Asked Questions
Find answers to the most common questions about Slip On Flanges — including SORF vs SOFF, pressure class selection, welding procedure, and ordering. If you need further technical assistance, our in-house metallurgical engineers are available to help.
Related Products
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