Titanium H Grades Win Approval For ASME Boiler and Pressure Vessel Specifications

The ITA Global Industrial Applications Committee of the International Titanium Association (ITA) recently released the following announcement:

ASME’s Section VIII Division 2, titanium H Grades Case #3059

Approval Date: September 6, 2022

The Global Industrial Applications Committee of the ITA, in 2019 launched a collaborative project composed of Chemical Processing Industry (CPI) companies, titanium fabricators and other interested parties to work together to develop a “Code Case” for titanium “H” alloy grades to be included in the ASME’s Section VIII Division 2.

The motivation to pursue this project was based on the desire to improve efficiency in the use of titanium to fabricate pressure containing process equipment and thus reduce the overall cost of the equipment, according to the ITA’s Applications Committee.

Having won approval, the ITA’s Global Industrial Committee is now looking to establish an alliance among the association such as metallurgists, chemical companies (end users who would specify titanium Grade 2H or the other H grades, for pressure vessels) and fabricators (who would design and fabricate using these alloys in Division 2).

Rob Henson, chairman of the ITA Global Industrial Applications Committee acknowledged the project was deeply indebted to our ASME champion Bill MacDonald for taking the lead and guiding the H Grade Code Case through the various stages of the ASME approval process.

This Code Case verifies that titanium H Grades have higher mechanical properties as their non-H counterparts listed in current ASME Division 2 specifications for pressure vessels, and would develop the “design allowable” stress levels at the various temperatures of use—up to 600o F.

The ASME Boiler and Pressure

ASME’s Section VIII Division 2, titanium H Grades

Case No. 3059

Approval Date: September 6, 2022

Unalloyed and Palladium or Ruthenium Enhanced Titanium H grades with 400 MPa (58 ksi) MPa Minimum UTS, UNS R50400, UNS R52400, UNS R52402, and UNS R52404; Section VIII, Division 2

• The maximum allowable stress values, Section VIII, Division 2, Class 2.

• All other rules for Section VIII, Division 2 applicable to titanium shall be met.

• This Code Case number shall be shown on the Manufacturer’s Data Report.

Vessel Code (ASME BPV) allows for the use of 17 different titanium alloys in Section VIII Division 1, including titanium Grade 2 and Grade 2H. These grades are CP titanium alloys with differing levels of interstitial oxygen, iron and carbon in the metal structure, with clearly defined (and different) tensile strengths of 50 ksi and 58 ksi, respectively.

In this ASME Code Section, there are also several other titanium grades, based on titanium Grade 2 chemistry with Grade 2 mechanical properties that have an “H” grade designated. The list includes titanium Grades 7 and 7H, 16 and 16H and 26 and 26H (all of these grades are already included in ASTM specifications).

Michael Stitzlein, ITA Global Industrial Applications Committee member and president of Tricor Metals, said the ability to use the titanium “H” grades for the design and fabrication of ASME Code vessels would “allow for fabricators to potentially offer thinner wall vessels at a potentially lower cost to the Chemical Processing Industry.” The possibility of also offering Division 2-designed vessels as an alternative to titanium clad vessels also exists and could result in lower cost as well as shorter lead times for vessel fabrication.

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Titanium H grades are a class of CP grades that have a higher minimum ultimate tensile stress than non-H titanium grades. The ASME BPV is the standard that regulates the design and construction of boilers and pressure vessels, and requires that construction materials used in pressure vessels must be approved by the society and be in the material standards.

Bill MacDonald, director, technical sales for Titanium Metals Corp. (Timet), speaking at the Corrosion 2021 TEG 120X Reactive Metals Conference held in Houston, provided insights and context on titanium H grade Code Case for ASME Section VIII division. MacDonald began his presentation by stating that, in the 1990s, the Materials Technology Institute (MTI), based in St. Louis, and the ITA, sponsored a study to investigate improved properties in CP titanium. It was determined that, if changes could be made in the ASME BPV code, it would “significantly impact” the cost of titanium pressure equipment such as piping, tanks and heat transfer equipment, according to MacDonald.

The Industrial Applications Committee hosted the TCI Reactive Metals technical exchange forum during the AMPP Annual Conference on Sunday, 19 March 2023. Click here to view proceedings.