Slip-on Flange — ASME B16.5
Also written SORF
Slip-on flange — a flange that slides over the pipe and is fillet-welded inside and outside. Choose a slip-on flange for lower-pressure lines where easy alignment and lower cost matter more than fatigue strength. It needs less precise pipe cutting than a weld neck.
- ASME B16.5
- 23 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is a slip-on flange?
A slip-on flange is a flange that slides over the pipe and is fillet-welded inside and outside. Choose a slip-on flange for lower-pressure lines where easy alignment and lower cost matter more than fatigue strength. It needs less precise pipe cutting than a weld neck.
Standards for slip-on flanges
Slip-on Flange: What to Know Before Ordering
- Two fillet welds: one at the hub, one inside the bore
- Lower fatigue life than a weld neck in cyclic service
- Available with a hub or as a plate (hubless) design
Slip-on Flange Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 slip-on flange | ASTM B564 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L slip-on flange | ASTM A182 F904L | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 slip-on flange | ASTM A182 F304 | General corrosion resistance, food, water and architectural work |
| SS 304L slip-on flange | ASTM A182 F304L | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S slip-on flange | ASTM A182 F310 | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L slip-on flange | ASTM A182 F316L | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 slip-on flange | ASTM A182 F321 | High-temperature service between 425 and 815 °C |
| SS 347 slip-on flange | ASTM A182 F347 | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 slip-on flange | ASTM A182 F51 / F60 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 slip-on flange | ASTM A182 F53 | Seawater and high-chloride service where strength also matters |
| Inconel 600 slip-on flange | ASTM B564 | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 slip-on flange | ASTM B564 | Seawater, high strength and high temperature in one alloy |
| Inconel 718 slip-on flange | project / purchase specification dependent | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT slip-on flange | ASTM B564 | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 slip-on flange | ASTM B462 / B564 | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 slip-on flange | ASTM B462 / B564 | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 slip-on flange | ASTM B564 | Seawater, hydrofluoric acid and marine service |
| Monel K500 slip-on flange | project / purchase specification dependent | High-strength pump shafts, bolting and springs in seawater |
| Super Duplex S32760 slip-on flange | ASTM A182 F55 | Seawater firewater, injection and offshore piping |
| ASTM A106 Gr B slip-on flange | ASTM A105 | High-temperature process and steam piping in refineries and power plants |
| ASTM A333 Gr 6 slip-on flange | ASTM A350 LF2 | Cold-climate and refrigerated piping down to −45 °C |
| ASTM A335 P11 slip-on flange | ASTM A182 F11 | Steam and hot-oil piping up to about 550 °C |
| ASTM A335 P22 slip-on flange | ASTM A182 F22 | High-pressure steam and hydrogen service up to about 580 °C |
Other flanges
Slip-on Flange dimensions — ASME B16.5 Class 150 & 300
Outside diameter, thickness and bolting are set by size and class. Values in mm; thickness excludes the 1.6 mm raised face.
| NPS | Cl 150 OD | Cl 150 thickness | Cl 150 bolt circle | Cl 150 bolts | Cl 300 OD | Cl 300 thickness | Cl 300 bolt circle | Cl 300 bolts |
|---|---|---|---|---|---|---|---|---|
| ½" | 90 | 9.6 | 60.3 | 4 × ½" | 95 | 12.7 | 66.7 | 4 × ½" |
| 1" | 110 | 12.7 | 79.4 | 4 × ½" | 125 | 15.9 | 88.9 | 4 × ⅝" |
| 1½" | 125 | 15.9 | 98.4 | 4 × ½" | 155 | 19.1 | 114.3 | 4 × ¾" |
| 2" | 150 | 17.5 | 120.7 | 4 × ⅝" | 165 | 20.7 | 127.0 | 8 × ⅝" |
| 3" | 190 | 22.3 | 152.4 | 4 × ⅝" | 210 | 27.0 | 168.3 | 8 × ¾" |
| 4" | 230 | 22.3 | 190.5 | 8 × ⅝" | 255 | 30.2 | 200.0 | 8 × ¾" |
| 6" | 280 | 23.9 | 241.3 | 8 × ¾" | 320 | 35.0 | 269.9 | 12 × ¾" |
| 8" | 345 | 27.0 | 298.5 | 8 × ¾" | 380 | 39.7 | 330.2 | 12 × ⅞" |
| 10" | 405 | 28.6 | 362.0 | 12 × ⅞" | 445 | 46.1 | 387.4 | 16 × 1" |
| 12" | 485 | 30.2 | 431.8 | 12 × ⅞" | 520 | 49.3 | 450.8 | 16 × 1⅛" |
Full chart: ASME B16.5 flange dimensions.
Slip-on flange — questions buyers ask
What is a slip-on flange?
A slip-on flange is a flange that slides over the pipe and is fillet-welded inside and outside. Choose a slip-on flange for lower-pressure lines where easy alignment and lower cost matter more than fatigue strength. It needs less precise pipe cutting than a weld neck.
Slip-on or weld neck — which is stronger?
The weld neck. A slip-on flange is fine for moderate pressure and temperature, but in cyclic or severe service engineers specify weld neck flanges.
Which grades are slip-on flanges available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Monel K500, Super Duplex S32760, ASTM A106 Gr B, ASTM A333 Gr 6, ASTM A335 P11, ASTM A335 P22.
Which standard covers slip-on flange dimensions?
ASME B16.5 · EN 1092-1. The material standard depends on the grade.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026