ASME Tank Heads

An ASME tank head, also known as an ASME tank end cap, refers to a component used to close the end of a pressure vessel and isolate the vessel contents from the external environment. It is an essential component of pressure vessel equipment and is widely used in industries such as petrochemicals, metallurgy, pharmaceuticals, food processing, engineering equipment, and many others.

1. Pressure Vessel

When installing an ASME tank head on a pressure vessel, it is generally necessary to install heads at both ends of the vessel. Depending on the type and function of the vessel, the installation position may vary.

(1) A flat head is generally installed at the top of a pressure vessel and serves as a top closure.

(2) A spherical head is generally installed at the bottom of the vessel and helps provide structural support and improve stability.

(3) An elliptical or semi-elliptical head is installed at the top of the vessel to reduce stress concentration in the upper section of the vessel.

2. Heat Exchanger

When installing a dish head on a heat exchanger, heads are generally installed at both ends of the heat exchanger. Depending on the type and function of the heat exchanger, the installation position may vary.

(1) A fixed tube-sheet shell-and-tube heat exchanger is generally mounted on a manufacturing frame, with heads installed at both ends to seal the tube-side and shell-side spaces, respectively.

(2) The spherical head of a floating-head heat exchanger is installed on the floating head, allowing it to accommodate thermal expansion and contraction caused by changes in temperature and pressure.

(3) The head of a plate heat exchanger is generally installed on the side and serves to seal the heat exchanger plates and flow channels.

3. Reactor

When installing a reactor head, the selection should generally be based on the reactor structure and operating environment. In general, the reactor head should be installed above the reactor body or cover to provide structural stability and sealing performance.

The United States was the first country in the world to establish pressure vessel codes. From the late 19th century to the early 20th century, boiler and pressure vessel accidents occurred frequently, resulting in significant casualties and property damage. In 1911, the American Society of Mechanical Engineers (ASME) established the Boiler and Pressure Vessel Committee to develop and maintain codes for the design, manufacturing, and inspection of boilers and pressure vessels.

In the spring of 1915, the world's first pressure vessel code was published: the Boiler Construction Code, 1914 Edition. This marked the beginning of the ASME Boiler and Pressure Vessel Code (hereinafter referred to as the ASME Code), which later developed into ASME Section I, Power Boilers.

Currently, the ASME Code consists of 12 sections covering boilers, pressure vessels, nuclear power plants, welding, materials, nondestructive examination, and other related areas. These sections are extensive and comprehensive, covering the quality assurance requirements for boilers and pressure vessels. A new edition of the ASME Code is published every three years (changed to every two years after 2013), with updates issued twice a year. Structurally, the ASME Code includes four types of documents: Code, Code Cases, Interpretations, and Addenda.

The ASME Code sections related to pressure vessel design mainly include Section II Materials, Section III Rules for Construction of Nuclear Facility Components, Section V Nondestructive Examination, Section VIII Rules for Construction of Pressure Vessels, Section X Fiber-Reinforced Plastic Pressure Vessels, Section XI Rules for Inservice Inspection of Nuclear Power Plant Components, and Section XII Rules for Construction and Continued Service of Transport Tanks.

ASME Section VIII is divided into three divisions: Division 1 Pressure Vessels, Division 2 Alternative Rules for Pressure Vessels, and Division 3 Alternative Rules for Construction of High Pressure Vessels. These are commonly referred to as ASME VIII-1, ASME VIII-2, and ASME VIII-3, respectively.