API RP 934-A-ed.3

Annotation of standard text API RP 934-A-ed.3 :

API RP 934-A, 3rd Edition, January 2019 - Materials and Fabrication of 21/4Cr-1Mo, 21/4Cr-1Mo-1/4V, 3Cr-1Mo, and 3Cr-1Mo-1/4V Steel Heavy Wall Pressure Vessels for High-temperature, High-pressure Hydrogen Service

This RP covers materials and fabrication requirements for new 21/4Cr and 3Cr steel heavy wall pressure vessels for high-temperature, high-pressure hydrogen service. For this RP, “heavy wall” is defined as a shell thickness of 4 in. (100 mm) or greater, and high-temperature is considered to be operating temperatures of 650 °F (345 °C) and above. This RP applies to vessels that are designed, fabricated, certified, and documented in accordance with ASME Section VIII, Division 2, including Paragraph 3.4, Supplemental Requirements for Cr-Mo Steels, and ASME Code Case 2151, as applicable.

Although outside of its scope, this RP can be used as a resource for vessels with wall thicknesses below 4 in. (100 mm), and/or operating at temperatures of less than 650 °F (345 °C), with changes defined by the purchaser. This document may also be used as a resource when planning to modify an existing heavy wall pressure vessel.

ASME Section VIII, Division 3 is typically used for much higher-pressure applications (beyond the hydroprocessing range); however, a specific Code Case developed for these alloys is available under Division 3. Division 3 has much stricter design rules (e.g. fatigue and fracture mechanics analyses are required) and material testing requirements, and application of these rules is outside the scope of this document.

Materials covered by this RP are conventional steels including standard 21/4Cr-1Mo and 3Cr-1Mo steels, and advanced steels which include 21/4Cr-1Mo-1/4V, 3Cr-1Mo-1/4V-Ti-B, and 3Cr-1Mo-1/4V-Nb-Ca steels. This document may be used as a reference document for the fabrication of vessels made of enhanced steels (steels with mechanical properties increased by special heat treatments such as ASME SA-542, Grade B, Class 4) at the purchaser’s discretion. However, no attempt has been made to cover specific requirements for the enhanced steels, and they may be different than the requirements for vanadium grade steels.

The interior surfaces of these heavy wall pressure vessels may have an austenitic stainless steel weld overlay lining to provide additional corrosion resistance. A lining of stainless steel cladding using a roll-bonded or explosion-bonded layer on Cr-Mo base metal may be acceptable, but this is outside the scope of this document. Multilayer vessels are also outside the scope of this document.

Heat exchanger shells and channels which meet the conditions listed above are within the scope of this RP. They are included in the term “pressure vessel” for the purposes of this RP.

This is the third edition of RP 934-A. The legacy first edition was API RP 934, Materials and Fabrication Requirements for 21/4Cr-1Mo & 3Cr-1Mo Steel Heavy Wall Pressure Vessels for High Temperature, High Pressure Hydrogen Service, published December 2000. The second edition was issued in May 2008, and it was the first version referred to as “934-A.” RP 934-A, second edition, later incorporated Annex A and then Annex B, which were issued in February 2010 and March 2012 as Addendum 1 and Addendum 2, respectively.