| Customization: | Available |
|---|---|
| Standard: | ANSI, DIN, GB, JIS, GOST, BSW, ISO |
| Type: | Alloy Steel Flange |
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Standard Designation: ASTM A335/A335M (Seamless Ferritic Alloy-Steel Pipe for High-Temperature Service)
Material Grades: P5, P9, P11, P22, P91 (common grades for flanges)
Scope: Designed for high-temperature and high-pressure applications in power plants, refineries, and petrochemical industries.
| Property | Technical Specifications |
|---|---|
| Chemical Composition | Chromium (Cr), Molybdenum (Mo), and Carbon (C) enhance creep resistance and oxidation stability at elevated temperatures. |
| Mechanical Strength | High tensile strength (≥415 MPa) and yield strength (≥205 MPa) across grades. |
| Temperature Range | Suitable for service up to 650°C (depending on grade). |
| Corrosion Resistance | Superior resistance to oxidation, sulfidation, and thermal fatigue in harsh environments. |
Oil & Gas: High-pressure pipelines, wellhead equipment.
Power Generation: Boiler systems, steam lines, turbine components.
Chemical Processing: Reactors, heat exchangers, and distillation columns.
Nuclear Plants: Critical piping systems requiring leak-proof performance.
Forging: Hot-forged from seamless alloy steel pipes to ensure structural integrity.
Heat Treatment: Normalized and tempered to achieve optimal hardness and ductility.
Testing: 100% non-destructive testing (NDT), hydrostatic testing, and Charpy impact tests per ASTM E23.
Performance: Retains mechanical properties under prolonged thermal stress.
Durability: Resistant to thermal fatigue and creep deformation.
Compliance: Meets ASME B16.5, B16.47, and NACE MR0175 for sour service environments.
Customization: Available in classes #150 to #2500, RF/FF/RTJ face types, and sizes ½" to 24".
Target Industries: Refineries, thermal power plants, LNG facilities.
Key Selling Points:
Cost-effective alternative to stainless steel for high-temperature applications.
Proven performance in critical infrastructure projects (e.g., refinery expansions, offshore platforms).
Certifications: Ensure suppliers provide Mill Test Certificates (MTC) with traceable heat numbers.
Surface Finish: Specify anti-corrosion coatings (e.g., hot-dip galvanizing) for corrosive environments.
Lead Time: Opt for suppliers with in-house forging and testing facilities to reduce delays.
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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