Titanium Flange Pressure Rating: Pressure, Temperature and Class Selection Guide

Choosing a titanium flange based on its pressure class only can be misleading and that’s because titanium flange pressure rating can change with operating temperature, material specification, and applicable standards. If you overlook these factors, you may end up selecting the wrong flange for your system’s operating conditions.

What is the Pressure Rating of a Titanium Flange?

A titanium flange pressure rating is the maximum pressure the flange is allowed to handle at a specified temperature, material, and pressure class. It is not one fixed pressure for every condition. For example, if a flange can handle 500 psi at 100°F, you cannot assume it can still handle 500 psi when the temperature rises to 500°F.

The allowable pressure may be lower at the higher temperature. This is why the number in a pressure class does not tell you the exact pressure a flange can handle. A Class 300 flange, for example, is not simply rated for 300 psi. You need to check the pressure-temperature rating that applies to the flange material and operating temperature.

How Is Titanium Flange Pressure Rating Determined?

To determine the pressure a titanium flange can safely handle, several factors work together to achieve this. You cannot choose a pressure class in isolation and assume it will suit every application. Detailed below are some factors to determine titanium flange pressure rating.

Titanium Material Grade

Titanium flanges are available in different grades, and the grade matters when you need to determine the applicable pressure rating. For example, manufacturers commonly supply Grade 2 titanium flange and Grade 5 titanium flanges to ASTM B381 specifications. The rating must therefore match the specification of the titanium flange you are selecting rather than treating as a general rating for all titanium.

Operating Temperature

Temperature can reduce the pressure a flange is allowed to handle. For example, a flange that can handle 600 psi at 200°F may not be able to handle a higher temperature of about 500°F. This is why it is important you check the rating with your system’s actual temperature rather than using a room-temperature value.

Pressure Class

Pressure class gives you a starting point for selecting a flange. Common ASME B16.5 classes include 150, 300, 400, 600, 900, 1500, and 2500. The class number does not mean the flange can handle that exact pressure in psi. Instead, you use the class together with the applicable material and temperature rating to determine the allowable pressure.

Flange Size and Design

The size and design of the flange also need to match the applicable standard. ASME B16.5 specifies dimensions for flanges and flanged fittings, while different flange types have their own required dimension. Hence always confirm that the flange size, type, and pressure class match the piping system and the applicable standard.

Pressure-Temperature Rating

The pressure-temperature rating brings these factors together. It tells you the maximum allowable working pressure for a particular material and pressure class at a specified temperature. Therefore checking this rating against your system’s actual pressure and temperature helps you determine whether the selected titanium flange is suitable for your intended operation.

Titanium Flange Pressure-Temperature Rating Table

Titanium Grade 5 Flange Pressure-Temperature Rating

Temperature °F	Class 150 (psi)	Class 300 (psi)	Class 400 (psi)	Class 600 (psi)	Class 900 (psi)	Class1500 (psi)	Class 2500 (psi)
-20 to 100	275	720	960	1440	2160	3600	6000
200	230	600	800	1200	1800	3000	5000
300	205	540	720	1080	1620	2700	4500
400	190	495	660	995	1490	2485	4140
500	170	465	620	930	1395	2330	3880
600	140	435	580	875	1310	2185	3640
650	125	430	575	860	1290	2150	3580
700	110	425	565	850	1275	2125	3540
750	95	415	555	830	1245	2075	3460
800	80	405	540	805	1210	2015	3360
850	65	395	530	790	1190	1980	3300
900	50	390	520	780	1165	1945	3240
950	35	380	510	765	1145	1910	3180
1000	20	320	430	640	965	1605	2675
1050	20	310	410	615	925	1545	2570
1100	20	255	345	515	770	1285	2145
1150	20	200	265	400	595	995	1655
1200	20	155	205	310	465	770	1285
1250	20	115	150	225	340	565	945
1300	20	85	115	170	255	430	715
1350	20	60	80	125	185	310	515
1400	20	50	65	95	145	240	400
1450	15	35	45	70	105	170	285
1500	10	25	35	55	80	135	230

Titanium Flange Pressure Ratings by Class

Titanium flanges are available in several pressure classes, including Class 150, 300, 400, 600, 900, 1500, and 2500. The class you need depends on the temperature pressure requirements of your system. The figures below are Grade 5 titanium flange data to show you how some of the classes compare from the above table.

Class 150

Class 150 is the lower end of the ASME B16.5 pressure classes covered in this range. For Grade 5 titanium, the above pressure-temperature table lists 275 psi from -20 to 100°F and 170 psi at 500°F, showing why you should not select a Class 150 flange by class number alone.

Class 300

The class 300 provides a little bit higher allowable pressure than the class 150 under the same conditions. The table lists 720 psi from -20 to 100°F and 465 psi at 500°F. If your system operates at a higher temperature, check the rating at that temperature instead of just relying on the Class 300 designation.

Class 600

The class 600 is intended to handle a higher pressure need than the classes 150 and 300. In the same data, the allowable pressure is 1,440 psi from -20 to 100°F and 930 psi at 500°F. Your operating temperature still needs to be checked before treating the class as suitable.

Class 900

Class 900 provides a much higher pressure rating when compared to class 600 under the same temperature conditions. The figures are 2,160 psi from -20 to 100°F and 1,395 psi at 500°F. The actual allowable pressure must still be taken from the applicable pressure-temperature rating.

Class 1500

Where the piping system requires a really high pressure class, the class 1500 is needed. The data gives 3,600 psi from -20 to 100°F and 2,330 psi at 500°F. This does not mean every class 1500 titanium flange has these exact ratings; the material specification and temperature must match the rating table.

Class 2500

Class 2500 is the highest pressure class covered by ASME B16.5 for the flange sizes within its scope. The table lists 6,000 psi from -20 to 100°F and 3,880 psi at 500°F. ASME B16.5 limits Class 2500 flanges to NPS 1/2 through NPS 12, so you need to check size and standard requirements.

Standards and Specifications for Titanium Flange

When you select a titanium flange, the standard tells you what requirements the product needs to meet. For pressure rating, material specification and flange dimensions, these three standards may come up in your research. However, they do not all apply to titanium flanges in the same way.

ASME B16.5

ASME B16.5 is the main flange standard to check for titanium flanges within its size range. It covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and flange joints for NPS 1/2 through NPS 24. It also covers Class 150 through 1500, plus Class 2500 for NPS 1/2 through NPS 12. When you are checking a titanium flange’s pressure rating, the applicable material and pressure class must match the requirements in the standard.

ASTM B381

ASTM B381 is a material specification rather than a flange pressure-rating standard. It covers titanium and titanium-alloy forgings and sets requirements such as chemical composition and mechanical properties for the specified grades. Titanium Industries, for example, lists Grade 2 titanium flanges to ASTM B381 F2 and ASME SB-381.

This distinction matters when checking a flange. ASTM B381 tells you about the titanium forging material, while ASME B16.5 addresses the flange’s dimensions and pressure-temperature rating. You should therefore check both specifications when the product is specified to these standards.

ASME B16.47

ASME B16.47 covers large-diameter steel flanges from NPS 26 through NPS 60. It includes pressure-temperature ratings, materials, dimensions, tolerances, marking and testing, with rating classes 75 through 900. Because its scope is specifically large-diameter steel flanges, it should not be presented as the standard for ordinary titanium flanges.

If a project involves a large-diameter titanium flange, do not assume B16.47 applies simply because the flange is large. Check the project’s specified material and applicable design standard first.

How to Select the Right Titanium Flange Pressure Rating

Selecting the right pressure rating starts with your system’s operating conditions. You need to check the pressure and temperature that the flange will handle, then match those conditions with the titanium grade, pressure class, size, design, and applicable standard. Here are some things you should do to select the right titanium flange pressure rating for your system.

Determine the Design Pressure

Start by examining the highest pressure the flange is expected to handle under the conditions of your piping system. You shouldn’t use normal operating pressure alone if the system can experience higher pressure during startup, shutdown, or other foreseeable occurrence that you know of. The design pressure should represent the most severe expected pressure and temperature combination for the component.

Determine the Design Temperature

While selecting titanium flange pressure rating for your system, identify the highest temperature you expect the flange to experience at the designed pressure. This matters because the allowable pressure can change as temperature changes. So you must check the rating at the applicable temperature

Confirm the Titanium Grade

You need to confirm the exact titanium grade and material specification before selecting the pressure class. Titanium flanges are supplied in different grades, including Grade 2 and Grade 5, and manufacturers specify these grades separately. Make sure the pressure rating corresponds to the material specification being used.

Select the Appropriate Pressure Class

Once you know the design pressure, temperature, and material, use the applicable pressure rating table to select a pressure class that meets the required conditions. Do not assume a pressure class number represents the same pressure in psi.

Check Flange Size and Design

Confirm the flange’s nominal size, bore, type, facing, and other dimensional requirements against the applicable standard and your piping connection. We recommend you check details such as bolt circle, hole quantity, flange thickness, and gasket or facing requirements before selecting.

Verify the Applicable Standard

Check that the flange has the standard required dimension that your system needs. For example, ASME B16.5 covers pressure-temperature ratings and flange dimensions within its scope, while ASTM B381 covers titanium and titanium-alloy forgings. The material and dimensional standards should match the specification you need.

Consider the Operating Environment

Finally, you should check what the flange will be exposed to during operation. The fluid, corrosion conditions, temperature, and other operating requirements can affect the titanium grade and flange specification you need.

FAQs

What Happens If A Titanium Flange Is Exposed To Pressure Above Its Rating?

If you expose a titanium flange to pressure above its allowable rating the flange and its connection can be overstressed which may cause permanent deformation, gasket leakage, cracking, or even flange failure.

Does Bolt Material Affect The Pressure Rating Of A Titanium Flange?

Yes. Bolt material can affect the pressure capability of a titanium flanged connection if the bolts do not provide enough clamping force that is needed to maintain the gasket seal under operating conditions. Therefore you must always ensure that the flange, bolts, gasket, and connection are suitable as a complete assembly for the intended pressure and temperature.

What Is the Difference Between Flange Pressure Rating and Design Pressure?

The flange pressure rating is the maximum allowable pressure that a flange can handle at a specific temperature, material group, and pressure class according to the applicable standard.

Design pressure on the other hand is the pressure that is being used to design the piping system or component for its intended service conditions. Simply put, the design pressure is a system design requirement, while the flange pressure rating is a capability established for the flange under specified conditions.

Why Does The Allowable Pressure Decrease As Temperature Increases?

Allowable pressure generally decreases as temperature increases because the material’s mechanical strength reduces at elevated temperatures. So as the flange material becomes less capable of resisting stress, the allowable pressure also reduces to maintain an appropriate safety margin. This is why you find flange pressure ratings given as pressure-temperature ratings, rather than as one fixed pressure value.

How Do You Read a Titanium Flange Pressure-Temperature Rating Table?

To read a titanium flange pressure table rating you have to start by identifying the flange pressure class and the applicable titanium material or material group. Then locate the operating or design temperature in the table and read across to find the corresponding maximum allowable pressure. That is, from titanium grade → pressure class → operating temperature → allowable pressure.

How Does Corrosion Affect The Long-Term Pressure Rating Of A Titanium Flange?

Corrosion can reduce the long-term pressure-carrying capability of your flange if it causes material loss, pitting, cracking, or other forms of damage. As the flange loses material, its thickness and structural strength decreases thereby increasing the stress under the same operating pressure.

However, titanium has excellent corrosion resistance in many environments, so corrosion related pressure degradation is generally less of a concern with titanium flanges than it is with many conventional metals.

Conclusion

Now you know that getting the right titanium flange pressure rating requires more than choosing a pressure class. By considering the conditions the flange will face in operation and following the guidance discussed in this article, you can make a more informed titanium flange pressure rating choice for your system.THT not only manufacture titanium flange, also produce titanium elbow, titanium tee,titanium stub end,titanium reducer，titanium end cap， titanium bolt etc. If you have such request, welcome to contact us.