| Customization: | Available |
|---|---|
| Standard: | ANSI, DIN, GB, JIS, GOST, BSW, BS |
| Type: | Forged/ Hot Press |
|
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| Parameter | ANSI B16.5 | GB/T9112-2000 |
|---|---|---|
| Size Range | NPS ½" to 24" (DN15 to DN600). | DN10 to DN4000. |
| Pressure Ratings | Class 150, 300, 400, 600, 900, 1500, 2500. | PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100. |
| Design Focus | High-pressure, high-temperature applications. | General industrial use, broader size coverage. |
Key Insight:
ANSI B16.5 is limited to smaller sizes (≤DN600) but offers higher pressure classes.
GB/T9112-2000 accommodates very large flanges (up to DN4000) with lower pressure ratings (≤PN100).
| Standard | Common Materials | Key Properties |
|---|---|---|
| ANSI B16.5 | ASTM A105 (forged), A350 LF2 (low-temp), A694 (high-yield). | Strict control of C, Mn, and trace elements; heat treatment mandatory for some grades. |
| GB/T9112-2000 | Q235B (carbon steel), 20# (ASTM A105 equivalent), 16Mn (high-strength low-alloy). | Focus on general mechanical properties; less stringent on trace elements. |
ANSI B16.5: Requires Charpy impact testing for low-temperature grades (e.g., A350 LF2).
GB/T9112-2000: Often uses Q235B for non-critical applications, with limited testing requirements.
| Feature | ANSI B16.5 | GB/T9112-2000 |
|---|---|---|
| Face Types | Raised Face (RF), Flat Face (FF), Ring-Type Joint (RTJ). | RF, FF, RTJ, and additional types like Male-Female (MF). |
| Bolt Hole Alignment | Drilled to ASME B16.5 templates. | Follows GB/T 9124 series (metric bolt circle). |
| Surface Finish | Serrated finish (125-250 µin) for RF flanges. | Smooth or spiral-grooved finish. |
Compatibility Note:
ANSI and GB flanges are not directly interchangeable due to differing bolt-hole patterns and dimensions. Adapters or custom machining may be required.
| Standard | Basis for Ratings | Typical Applications |
|---|---|---|
| ANSI B16.5 | ASME B16.5 pressure-temperature tables (based on material grade). | Refineries, power plants, offshore platforms. |
| GB/T9112-2000 | PN ratings derived from nominal pressure (1.0 MPa = PN10). | Water treatment, HVAC, general industrial piping. |
Example:
A Class 150 ANSI flange (≈PN20) has a higher pressure capacity than a PN16 GB/T flange.
| Process | ANSI B16.5 | GB/T9112-2000 |
|---|---|---|
| Forging/Casting | Mandatory for ASTM A105/A350; strict NDE (UT, MT). | Permits plate-cut flanges for large sizes; limited NDE requirements. |
| Heat Treatment | Normalizing/tempering required for A694 grades. | Optional for Q235B; mandatory for 16Mn. |
| Testing | Hydrostatic testing, PMI, hardness testing. | Visual inspection, dimensional checks. |
ANSI B16.5: Dominant in North America, Middle East, and global oil/gas projects.
GB/T9112-2000: Widely used in China, Southeast Asia, and for cost-sensitive infrastructure.
| Factor | ANSI B16.5 | GB/T9112-2000 |
|---|---|---|
| Material Cost | Higher (due to ASTM-grade materials). | Lower (uses Q235B or domestic equivalents). |
| Lead Time | Longer for high-pressure grades. | Shorter for standard sizes. |
| Standard | Typical Use Cases |
|---|---|
| ANSI B16.5 | - High-pressure oil/gas pipelines. - Chemical processing under extreme conditions. |
| GB/T9112-2000 | - Water supply systems. - Low-pressure steam lines. - General factory utilities. |
ANSI B16.5: Higher cost and complexity for large-diameter, high-class flanges.
GB/T9112-2000: Limited international recognition; may require additional certifications for global projects.
ANSI B16.5 flanges excel in high-pressure, high-integrity applications, while GB/T9112-2000 offers cost-effective solutions for general-purpose systems, especially in large sizes. Selection depends on project location, pressure requirements, and compliance needs. For multinational projects, hybrid systems with adapters or dual-standard flanges may be necessary.
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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