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Glossary Term: IEC
International Electrotechnical Commission. A worldwide organization for standardization. The object of the IEC is to promote international cooperation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, the IEC publishes international standards. See 61508 and 61511.
Glossary Term: Impact analysis
activity of determining the effect that a change to a function or component will have to other functions or components in that system as well as to other systems
Glossary Term: IDLH
Immediately Dangerous to Life and Health. Use in consequence analysis to estimate toxic effects on people.
Glossary Term: Hydrogen damage
Any of several forms of metal failure caused by dissolved hydrogen, including blistering, internal void formation, and hydrogen induced delayed cracking.
Glossary Term: HSE
(UK) Health and Safety Executive
Glossary Term: HMI/MMI
Human or Man Machine Interface. Refers to the software that the process operator “sees” the process with. An example HMI/MMI screen may show a tank with levels and temperatures displayed with bar graphs and values. Valves and pumps are often shown and the operator can “click” on a device to…
Glossary Term: Heuristic
Pertaining to a method of problem solving in which solutions are discovered by evaluation of the progress made toward the final solution, such as a controlled trial and error method. An exploratory method of tackling a problem, or sequencing of investigation, experimentation, and trial solution in closed loops, gradually closing…
Glossary Term: H&MB
Heat and Material Balance. An accounting of the distribution of the heat and material input and output for a process. Usually prepared as part of the process flow sheet or diagram (PFD) development early in an engineering project. Usually part of the input to a HAZOP or other hazard identification…
Glossary Term: HAZOP
Hazards and operability study. A process hazards analysis procedure originally developed by ICI in the 1970s. The method is highly structured and divides the process into different operationally-based nodes and investigates the behavior of the different parts of each node based on an array of possible deviation conditions or guidewords.
Glossary Term: Hazardous material
Any substance that requires special handling to avoid endangering human life, health or well being. Such substances include poisons, corrosives, and flammable, explosive or radioactive chemicals.
Glossary Term: Hazardous area
A US classification for an area in which explosive gas/air mixtures are, or may be expected to be, present in quantities such as to require special precautions for the construction and use of electrical apparatus. Division 1 (hazardous). Where concentrations of flammable gases or vapors exist a) continuously or periodically…
Glossary Term: Hazard Matrix
A category based method for assigning a safety integrity level (SIL). The user must create a matrix that assigns defined categories to the consequence (one axis dimension) and likelihood (other axis dimension) components of the risk with a SIL assignment associated for each entry in the matrix. In some cases,…
Glossary Term: HART
Highway Addressable Remote Transducer. The HART protocol was originated by Rosemount in the late 1980’s. The protocol was “open” for other companies to use and a User Group formed in 1990.
Glossary Term: Ground loop
Circulating current between two or more connections to electrical ground. This signal can be detected and displayed by electronic instruments. These signals are generally not associated with the variable to be measured and represent noise in the measuring system. They are typically broken (removed) by adding optical coupling devices to…
Glossary Term: Grab sampling
A method of sampling bulk materials for analysis, which consists of taking one or more small portions (usually only imprecisely measured) at random from a pile, tank, hopper, railcar, truck or other point of accumulation.
Glossary Term: Go/no go test
A test in which one or more parameters are determined, but which can result only in acceptance or rejection of the test object, depending on the value(s) measured.
Glossary Term: Globe valve
1. A valve with a closure piece that moves in a straight line, one or more ports, and a body distinguished by a globular shaped cavity around the port region. 2. A type of flow regulating valve consisting of a movable disc and a stationary ring seat in a generally…
Glossary Term: Gland
A device for preventing a pressurized fluid from leaking out of a casing at a machine joint, such as at a shaft penetration for a valve or pump. Also known as “gland seal.”
Glossary Term: Gate valve
A valve with a closing piece in the form of a flat or wedge shaped gate which may be moved linearly in or out of the flow stream. It has a straight through flow path.
Glossary Term: Gasket
A sealing member, usually made by stamping from a sheet of cork, rubber, metal or impregnated synthetic material and clamped between two essentially flat surfaces to prevent pressurized fluid from leaking through the crevice; typical applications include flanged joints in piping, head seals in a reciprocating engine or compressor, casing…
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