Boiler glossary

Boiler glossary M

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MARINE BOILERS -- Boilers designed to fulfil special demand from the merchant marine. An example of fire-tube boiler construction is the Scotch fire tube boiler that for a long time was a very common marine steam boiler.
In diesel engine propelled vessels vertical steam boilers are used to save space on the floor. One example of these boilers is the Sunrod boiler. Marine boilers are nowadays mainly used for heating purposes.
MAGNAFLUX -- Magnetic Particle Inspection is a non-destructive testing method for checking ferrous materials for cracks utilizing a solution of metal particles and fluorescent dye.
MAGNESIUM CARBONATE -- The magnesium carbonates are similar in their properties to the corresponding calcium salts, with the exception that the monocarbonate of magnesium is quite soluble, so that in order to, secure the precipitation of the magnesia it is necessary to convert it to the hydrate, which is relatively insoluble. The carbonate salts of lime and magnesia are commonly referred to as "temporary hardness," because they are precipitated to a considerable degree by merely heating the water, which drives off carbon dioxide from the bicarbonate, forming the monocarbonate, which, in the case of lime at least, is relatively insoluble.
MAGNESIUM SULPHATE -- Magnesium sulphate is highly soluble, but when calcium salts are also present in the boiler, it reacts with them, forming calcium sulphate, which is deposited as hard scale.
MAKEUP WATER -- Raw water that has been filtered and softened and then introduced into the hotwell to compensate for water loss in the system.
MANHOLE -- Opening in a drum that permits a person to crawl in for inspection
MANHOLE RING -- A reinforced ring of metal fitted around the manhole to provide local stiffness.
MANIFOLD -- A pipe or header for collection of a fluid from, or the distribution of a fluid to a number of pipes or tubes.
MARINE DIESEL OIL -- Marine Diesel Oil is a middle distillate fuel oil which can contain traces, often 10% or more, of residual fuel oil from transportation contamination and/or heavy fuel oil blending. The MDO does not require heated storage.
MDO -- Abbreviation for Marine Diesel Oil
MEMBRANE PANEL -- Tubes welded together to form a water wall  Membrane-panel
MICA -- A group of silicates which crystallize in the monoclinic system; they have similar chemical compositions and highly perfect basal cleavage. Mica is one of the best electrical insulators.
MICHELL BEARING -- A thrust or journal bearing in which pivoted pads support the thrust collar or journal in such a way that they tilt slightly under the wedging action of the lubricant induced between the surfaces by their relative motion. The fluid lubrication conditions thus produced result in a very low friction coefficient and power loss in the bearing.
MODULATING BURNER -- A burner which can vary output intensity continuously from maximum fire down to a minimum point.
MOISTURE IN STEAM -- Particles of water carried in steam, expressed as the percentage by weight.
MONOTUBE BOILER -- A boiler consisting of a single tube. Feed water enters at one end and steam leaves at the other.
MOTIVE PRESSURE -- Line velocity pressure in steam piping.
MUD DRUM -- The bottom drum of a water tube boiler. A blow down line is normally installed from this drum for draining.
MULTIPLE-EXPANSION STEAM ENGINE -- An steam engine in which the expansion of the steam is divided into two or more stages, which are performed successively in cylinders of increasing size. Compound engine, Triple expansion engine, Quadruple expansion engine.
MULTI-STAGE BURNER -- A burner with more than two discrete stages of output intensity.