Glossary of Terms

API Storage Tank

A tank designed to the specifications of the American Petroleum Institute. These storage tanks are an essential element in the production, refining, transportation, and marketing of petroleum products. API maintains several documents that address the design, fabrication, operation, inspection, and maintenance of aboveground (AST’s) and underground (UST’s) storage tanks.


The American Society of Mechanical Engineers (ASME) is a professional body, specifically an engineering society, focused on mechanical engineering. The organization is known for setting codes and standards for mechanical devices. The “R” indicates for the repair and the “U” stamp allows for the fabrication of ASME code vessels.

Coiled Tank

Coiled tanks are generally used in the chemical industry. Half-pipe jackets are welded to a storage tank or pressure vessel. They are excellent tools for heating or cooling the contents of a tank.

Duplex Stainless Steel

Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim being to produce a 50/50 mix, although in commercial alloys, the mix may be 40/60 respectively. Duplex steels have improved strength over austenitic stainless steels and also improved resistance to localized corrosion, particularly pitting, crevice corrosion and stress corrosion cracking. They are characterized by high chromium (19-28%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. The most used Duplex Stainless Steel are the 2205 (22% Chromium, 5% Nickel) and 2507 (25% Chromium, 7% Nickel) sometimes the 2507 is also called “Super Duplex” due to the higher corrosion resistance.


Digesters are usedin the Pulp & Paper Industry to convert trees to paper, one must chip the wood and then “cook” the chips in what appears to be a huge steam pressure cooker. The chips are mixed with chemicals that will dissolve out the lignin, turpentine-like components that bind the fibers together as wood. Once those binders are removed, the loose fibers can then be recombined in a flat product, paper.

Flux-cored Arc Welding (FCAW)

Flux-cored arc welding is a semi-automatic or automatic arc welding process. FCAW requires a continuously-fed consumable tubular electrode containing a flux and a constant voltage or, less commonly, a constant electric current welding power supply. An externally supplied shielding gas is sometimes used, but often the flux itself is relied upon to generate the necessary protection from the atmosphere. The process is widely used in construction because of its high welding speed and portability.

Gas Metal Arc Welding (GMAW)

Gas metal arc welding, sometimes referred to by its subtypes metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun. GMAW is the most common industrial welding process, preferred for its versatility, speed and the relative ease of adapting the process to robotic automation.

Gas Tungsten Arc Welding (GTAW)

Gas tungsten arc welding, also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a nonconsumable tungsten electrode to produce the weld. GTAW is most commonly used to weld thin sections of stainless steel and light metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing procedures such as shielded metal arc welding and gas metal arc welding, allowing for stronger, higher quality welds. However, GTAW is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques.

Heat Exchanger

A heat exchanger is a device built for efficient heat transfer from one medium to another, whether the media are separated by a solid wall so that they never mix, or the media are in direct contact. They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, and natural gas processing.


The National Board Inspection Code is the only standard recognized worldwide for in-service inspection repairs and alterations of boilers and pressure vessels. This American National Standard has been adopted by a number of states and jurisdictions, as well as by federal regulatory agencies including the U.S. Department of Transportation. The National Board of Boiler and Pressure Vessel Inspectors was created in 1919 to promote greater safety to life and property through uniformity in the construction, installation, repair, maintenance, and inspection of boilers and pressure vessels. The National Board membership oversees adherence to codes involving the construction and repair of boilers and pressure vessels.

Shielded Metal Arc Welding (SMAW)

Shielded metal arc welding is also known as manual metal arc welding (MMA) or stick welding. Electric current is used to strike an arc between the base material and consumable electrode rod, which is made of steel and is covered with a flux that protects the weld area from oxidation and contamination by producing CO2 gas during the welding process. The electrode core itself acts as filler material, making a separate filler unnecessary.

Submerged Arc Welding (SAW)

Submerged arc welding is a high-productivity welding method in which the arc is struck beneath a covering layer of flux. This increases arc quality since contaminants in the atmosphere are blocked by the flux. The slag that forms on the weld generally comes off by itself, and combined with the use of a continuous wire feed, the weld deposition rate is high. Working conditions are much improved over other arc welding processes, since the flux hides the arc and almost no smoke is produced. The process is commonly used in industry, especially for large products and in the manufacture of welded pressure vessels.


The Tubular Exchanger Manufacturers Association, Inc. (TEMA) is a trade association of leading manufacturers of shell and tube heat exchangers, who have pioneered the research and development of heat exchangers for over sixty years. The TEMA Standards and software have achieved worldwide acceptance as the authority on shell and tube heat exchanger mechanical design.


It is a light, strong, lustrous, corrosion-resistant (including to sea water and chlorine) transition metal with a grayish color. The two most useful properties of the metal form are corrosion resistance, and the highest strength-to-weight ratio of any metal. In its unalloyed condition, titanium is as strong as some steels, but 45% lighter.