| Customization: | Available |
|---|---|
| Standard: | ANSI, DIN, GB, JIS, GOST, BSW, BS |
| Type: | Forged/ Hot Press |
|
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| Parameter | Details |
|---|---|
| Size Range | DN10 (10 mm nominal bore) to DN3000 (3000 mm nominal bore). |
| Pressure Ratings | PN6 to PN100 (EN 1092-1) / Class 150 to Class 2500 (ASME B16.5/B16.47). |
| Material Grades | ASTM A105 (forged), A350 LF2 (low-temp), A694 (high-yield for pipelines). |
| Face Types | Flat Face (FF), Raised Face (RF), Ring-Type Joint (RTJ), Tongue & Groove. |
Carbon Steel Grades:
ASTM A105: Standard forged carbon steel for ambient/high-temp service (≤425°C).
ASTM A350 LF2: Low-temperature carbon steel for -46°C to 340°C.
ASTM A694: High-strength grades (F42 to F80) for pipeline flanges (e.g., oil & gas).
Chemical Composition (Typical):
C: 0.25-0.35% (varies by grade).
Mn: 0.6-1.05% (improves toughness).
Si, S, P: Controlled for weldability and strength.
Mechanical Properties:
Tensile Strength: 485-620 MPa (ASTM A105).
Yield Strength: 250-415 MPa.
Hardness: ≤187 HB (ASTM A105).
Forging: Common for small-to-medium sizes (DN10-DN600). Provides superior grain structure and strength.
Casting: Used for large/demanding sizes (DN600-DN3000). Requires post-weld heat treatment (PWHT).
Plate Cutting: For large custom flanges (DN1500+), cut from steel plates and machined.
Machining: CNC machining ensures precise face finish (RF, RTJ) and bolt-hole alignment.
Key Challenges for Large Flanges (DN1500+):
Residual stress management during welding/forming.
Dimensional stability during heat treatment.
| Size Range | Typical Applications |
|---|---|
| DN10-DN50 | Instrumentation lines, sampling systems, low-pressure utilities. |
| DN50-DN300 | Process piping in refineries, chemical plants, HVAC systems. |
| DN300-DN1200 | Oil/gas transmission pipelines, water treatment plants, power generation. |
| DN1200-DN3000 | Offshore platforms, LNG terminals, large-scale water distribution networks. |
| Standard | Scope |
|---|---|
| ASME B16.5 | Pipe flanges up to DN600 (NPS 24). |
| ASME B16.47 | Large-diameter flanges (DN650-DN3000, Series A/B). |
| EN 1092-1 | European flange standards (PN6-PN100). |
| ISO 7005 | International standard combining ASME and DIN specifications. |
| NACE MR0175 | Compliance for sour service (H<sub>2</sub>S environments). |
Hydrostatic Testing: Mandatory for high-pressure flanges (e.g., Class 300+).
Ultrasonic Testing (UT): Detects internal defects in forged/cast flanges.
Hardness Testing: Ensures material meets grade requirements.
Dimensional Inspection: Critical for large flanges to ensure bolt-hole alignment and flatness.
PMI (Positive Material Identification): Verifies chemical composition.
Cost-Effective: Lower material cost compared to stainless steel/alloys.
High Strength: Suitable for high-pressure/temperature applications.
Weldability: Compatible with common welding techniques (SMAW, GTAW).
Versatility: Available in all standard sizes and pressure ratings.
| Issue | Solution |
|---|---|
| Corrosion Susceptibility | Coatings (e.g., epoxy, galvanizing) or cladding with stainless steel. |
| Brittleness at Low Temp | Use ASTM A350 LF2/LF3 grades for sub-zero environments. |
| Weight (Large Sizes) | Optimize design (e.g., reducing hub thickness) or use lightweight alloys. |
DN3000+ Custom Flanges: Growing demand for renewable energy projects (e.g., offshore wind).
Digitalization: Use of 3D scanning for dimensional verification of large flanges.
Sustainability: Increased use of recycled steel in flange manufacturing.
Carbon steel flanges from DN10 to DN3000 are indispensable in global industrial infrastructure. Smaller flanges (DN10-DN300) prioritize precision and cost efficiency, while large-diameter flanges (DN1200-DN3000) require advanced engineering to manage structural integrity and installation challenges. Material selection, adherence to standards (ASME/EN), and rigorous testing ensure reliability across diverse applications.
The pressure-temperature rating is the maximum allowable working pressure (bar unit) of the material and grade used at the rated temperature (Celsius).
Whether flange joints are used at high or low temperatures, leakage due to external forces and moments generated by the connected piping or equipment should be considered. To prevent leakage, pipe flanges and flanged fittings should avoid the application of severe external loads and sharp thermal gradients.
Application at temperatures in the creep range will result in decreasing bolt loads as relaxation of flanges, bolts, and gaskets takes place. Flanged joints subjected to thermal gradients may likewise be subject to decreasing bolt loads. Decreased bolt loads diminish the capacity of the flanged joint to sustain loads effectively without leakage. At temperatures above 200°C (400°F) for Class 150 and above 400°C (750°F) for other class designations, flanged joints may develop leakage problems unless care is taken to avoid imposing severe external loads, severe thermal gradients, or both.
Some materials, especially some carbon steel materials, exhibit a significant decrease in ductility when used at low temperatures, and thus cannot withstand impact load, sudden stress changes, and high stress concentrations. Some regulations require an impact test even when the temperature is above -29 °C (−20°F).
No pressure test is required on the flange.
Flanged fitting should be tested for shell pressure.
Shell Pressure Test for Flanged Fittings
The shell pressure test for flanged fittings shall be at a pressure no less than 1.5 times the 38°C (100°F) pressure rating rounded off to the next higher 1 bar (25 psi) increment.
|
Flanged Fittings Size |
Duration, Sec |
|---|---|
|
NPS ≤ 2 |
60 |
|
2 1/2 ≤ NPS ≤ 8 |
120 |
|
NPS ≥ 10 |
180 |
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