An extensive range of titanium and titanium alloys are used for the manufacture of ASME B16.5 flanges covering Grade 1, Grade 2, Grade 3, Grade 7, Grade 9, Grade 12, etc. Generally, these flanges are available in Class 150 and Class 300. Among all the grades, commercially pure titanium Grade 2 flanges are most commonly utilized. In practice, titanium flanges can be used in two ways: (1) direct use of a solid titanium flange(weld neck, slip on, plate, threaded or blind); (2) a titanium stub end manufactured to ASME B16.9 with a carbon steel or stainless steel back ring(lap joint flange).

The “stub end + lap joint flange” solution is prevalent and cost-effective. However, in some cases, the solid integral titanium flanges could be required. Since ASME B16.5 doesn’t endorse titanium within the specification, its pressure-temperature ratings are not available in the standard. Basically, there are two methods to determine the pressure-temperature ratings for titanium flanges:

• Calculation shall be done in accordance with ASME Boiler and Pressure Vessel Code Section VIII, Division 1, Appendix 2. However, this will result in a gasket(RTJ) dependent flange.
• The titanium flanges shall be manufactured to ASME B16.5 dimensions. Its P-T ratings shall be calculated in accordance with ASME B16.5-2013 Appendix A and shall not exceed the rating ceiling pressure listed.