ASME B16.5 is the governing standard for pipe flanges and flanged fittings from NPS ½" to NPS 24" in pressure classes 150 through 2500. Covers dimensions, materials, pressure-temperature ratings, facing types, and bolt hole patterns. All ASME B16.5 materials from Arshya are available with EN 10204 3.1 or 3.2 certification.
Request ASME B16.5 Flange Quote| Class | A105 CS @ 100°F (psi) | F316L SS @ 100°F (psi) | F22 (2.25Cr) @ 100°F (psi) | Typical Application |
|---|---|---|---|---|
| 150 | 285 | 275 | 290 | Low-pressure utility, water, steam |
| 300 | 740 | 720 | 750 | General process piping, medium pressure |
| 600 | 1480 | 1440 | 1500 | Refinery, petrochemical, high-pressure process |
| 900 | 2220 | 2160 | 2250 | High-pressure steam, hot oil, gas transmission |
| 1500 | 3705 | 3600 | 3750 | High-pressure gas, boiler main steam, H₂ service |
| 2500 | 6170 | 6000 | 6250 | Ultra-high pressure, HP gas injection, hydroprocessing |
Ratings shown are at 100°F (38°C) ambient. All ratings decrease with increasing temperature — refer to ASME B16.5 Table 2 for the full P-T rating table at each temperature for each material group. Ratings above are approximate for reference only.
| Facing | Code | Gasket | Best For |
|---|---|---|---|
| Raised Face | RF | Spiral wound, graphite sheet, kammprofile | Standard for most process piping — Class 150 to 2500 |
| Ring Type Joint | RTJ | Oval or octagonal soft iron / 316L ring | High pressure (Class 600+), high temp, sour service (NACE) |
| Flat Face | FF | Full-face rubber or PTFE sheet | Mating with cast iron, brittle, or PTFE-lined flanges (Class 150) |
| Tongue & Groove | T&G | Thin flat ring seated in groove | Precision pressure containment — pumps, compressors, Class 150–2500 |
| Male & Female | M&F | Thin flat ring — male face inside female recess | Non-interchangeable precision fitting — heat exchangers |
| ASTM Grade | Material | ASME Group | Service |
|---|---|---|---|
| A105 | Carbon steel | 1.1 | General purpose — ambient to 425°C |
| A350 LF2 Cl.1 | Carbon steel (low-temp) | 1.1 | -46°C LNG terminal CS service |
| A182 F304L | 304L stainless | 2.1 (SS) | Food, water, cryogenic, chemical |
| A182 F316L | 316L stainless | 1.10 (SS) | Process, WFI, chemical, offshore |
| A182 F316 | 316 stainless | 1.13 (SS) | Standard 316 — process piping |
| A182 F11 Cl.2 | 1.25Cr-0.5Mo | 2.1 | High-temp steam, P11 alloy — PWHT required |
| A182 F22 Cl.3 | 2.25Cr-1Mo | 2.2 | Catalytic reformer, H₂ service — PWHT required |
| A182 F91 | 9Cr-1Mo-V | 5.2 | Supercritical boiler, P91 service |
| B564 N06625 | Inconel 625 | Nickel alloy | Offshore, LNG, high-alloy process |
| B564 N10276 | Hastelloy C-276 | Nickel alloy | HCl, wet chlorine, FGD, chemical plant |
ASME B16.5 defines six pressure classes. The class number is NOT the pressure rating in psi — it is a relative designation with pressure ratings varying by material group and temperature. For A105 carbon steel at 100°F (38°C): Class 150 = 285 psi, Class 300 = 740 psi, Class 600 = 1480 psi, Class 900 = 2220 psi, Class 1500 = 3705 psi, Class 2500 = 6170 psi. All ratings decrease as temperature increases — consult ASME B16.5 Table 2 for the full pressure-temperature tables. ASME B16.5 covers NPS ½" through NPS 24". For NPS 26"–60", use ASME B16.47 Series A (MSS SP-44) or Series B (API 605).
Raised face (RF) flanges have a raised sealing face that accepts a spiral wound, graphite, or kammprofile gasket — the most common facing for process piping. Ring type joint (RTJ) flanges have a machined groove accepting a metallic ring gasket (oval or octagonal) for a tighter metal-to-metal seal. RTJ is preferred for Class 600+ high-pressure, high-temperature service, sour environments (NACE MR0175), and applications where fire-safe bolted joint integrity is required. RTJ provides superior sealing in these demanding conditions. Flat face (FF) flanges are used when mating with brittle materials (cast iron, FRP) to prevent face damage from uneven bending loads.
ASME B16.5 flanges cover multiple material groups: A105 / A350 LF2 for carbon steel (LF2 to -46°C); A182 F304L / F316L for stainless steel (suitable to -196°C); A182 F11 Class 2 (1.25Cr-0.5Mo, P-No. 4) for high-temperature service with PWHT; A182 F22 Class 3 (2.25Cr-1Mo, P-No. 5A) for catalytic reformer and high-H₂ service with PWHT; A182 F91 (9Cr-1Mo-V) for supercritical boiler. For sour service, NACE MR0175 / ISO 15156 hardness limits apply — A105 and F11/F22 must meet maximum 200 HBW hardness, which typically requires PWHT. Nickel alloy flanges (Inconel 625, Hastelloy C-276) are available to ASTM B564 for the most demanding services.
