API 936 key terms

Unshaped refractory supplied as a dry mix or paste that is installed by casting, gunning, ramming, or spraying, then cured and heated to form a continuous lining without pre-fired brick joints.

A monolithic mix of refractory aggregate, binder, and additives that is mixed with water or a liquid binder and poured or vibrated into forms to form a dense lining.

A dry refractory blend designed to be conveyed pneumatically and sprayed with added water onto a surface, often used for repairs or for linings where formwork is impractical.

A stiff, moldable refractory supplied in a wet, clay-like condition that is pressed or rammed into place and then air-dried and fired, retaining shape without forms.

A hydraulic binder made mainly from limestone and bauxite that sets when mixed with water and provides strength and refractoriness in many castable and gunning mixes.

A castable with a calcium aluminate cement content typically below about four percent, giving improved density, hot strength, and volume stability compared with conventional cement-rich castables.

Graded mineral particles such as calcined clay, bauxite, alumina, or silica that form the bulk skeleton of a refractory mix and strongly influence density, strength, and service temperature.

The amount of water a dry refractory mix requires to reach a workable consistency for casting or gunning; excess water lowers strength, density, and spalling resistance.

The ability of a refractory to withstand rapid temperature changes without cracking, spalling, or losing structural integrity, influenced by expansion, conductivity, and microstructure.

A material property describing how readily heat passes through a refractory; low conductivity improves insulation, while high conductivity increases heat loss and shell temperature.

The compressive stress a cured or fired refractory specimen can withstand at room temperature, used as a quality indicator of density, bonding, and installation consistency.

The ease with which gases or liquids pass through a refractory pore structure, affecting dryout, steam escape, and resistance to penetration by molten slag or process gases.

A metal device welded to the vessel shell or casing that supports and retains a refractory lining, often shaped as a stud, V, or hook and designed for the expected temperature.

A hexagonal metal grid welded to a shell to hold and reinforce a refractory lining, commonly used in FCCU cyclones and other areas exposed to severe erosion and thermal cycling.

A gap or compressible insert placed in a refractory lining to allow thermal growth and prevent buckling, cracking, or overcompression when the lining heats up.

A small opening through a refractory lining or shell that allows moisture and steam to escape during dryout and service, reducing the risk of spalling and pressure buildup.

The surface of a refractory lining directly exposed to the process gas, flame, or molten material, which experiences the highest temperature and most severe chemical attack.

The maximum temperature or condition at which a refractory material can perform reliably without excessive deformation, corrosion, or failure under a defined set of operating exposures.

The distance between adjacent refractory anchors, which controls lining support, crack pattern, and resistance to spalling; spacing is selected from material type and service severity.

Temporary molds or panels that hold castable refractory in place until it sets, shaped to the required lining profile and removed before dryout and heat-up.

A placement method in which mixed castable is poured into forms and compacted with vibrating pokers or external vibrators to remove air and produce a dense, uniform lining.

A highly flowable refractory castable that spreads under its own weight without vibration, used where formwork is complex or access for vibrators is limited.

The controlled period after mixing and placement during which a hydraulic or chemical binder develops strength before drying; curing conditions affect final density and cracking.

Refractory material sprayed pneumatically onto a surface, either dry or wet process, often used for repairs, overhead work, or linings where formwork is impractical.

Material that bounces off the target surface during pneumatic spraying, representing waste and a change in mix consistency; excessive rebound can reduce lining quality.

A defined stage in an inspection and test plan where work must stop and be inspected or approved by a qualified party before the next activity may proceed.

A project document that lists inspections, tests, acceptance criteria, responsible parties, and hold or witness points required for refractory work.

A small sample of refractory prepared alongside the lining using the same materials and procedures, then tested to verify properties or retained as a reference.

A simple inspection method in which the lining is struck with a hammer and the sound is judged; a dull or hollow sound may indicate delamination or voids.

A cylindrical specimen cut from a finished refractory lining or test panel, used to measure thickness, density, strength, or other properties by laboratory testing.

The controlled removal of free water and chemically bound water from a refractory lining by heating at a prescribed slow rate before the unit is brought to operating temperature.

A planned schedule of temperature versus time used to dry out and heat a refractory lining, specifying heating rates, hold temperatures, and soak periods to avoid damage.

Sudden loss of chunks of refractory caused by rapid steam pressure buildup inside the lining when water turns to steam faster than it can escape through pores.

A form of refractory damage driven by steam pressure generated within a lining during heat-up, often appearing as shallow surface flakes or deeper bursts when venting is inadequate.