Metalwork and Steelwork Glossary

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2R + G

The sum of twice the rise and the going of a stair step. Approved Document K asks for 550 to 700mm. More

A

Anchor bolt

A bolt or fixing set into concrete or masonry to connect steelwork, such as a resin anchor or cast-in bolt.

Approved Document K

Government guidance for England on protection from falling, collision and impact, covering stairs, ramps, guarding and glazing. More

B

Balustrade

A barrier along the edge of a stair, landing, balcony or floor, made of posts, rails and infill such as glass or bars. More

Baseplate

A steel plate welded to the foot of a column or post, bolted to the foundation or structure below.

Bevel

An angled edge cut on a plate before welding, to let the weld penetrate the joint. More

Butt weld

A weld joining two parts edge to edge, often with bevelled edges for full penetration. More

C

Capping run

The final run or layer on the surface of a weld. More

Cleat

A short piece of angle or plate used to connect one member to another, usually with bolts.

Corrosivity category

A class from C1 (very low) to CX (extreme) describing how corrosive the atmosphere is, to ISO 9223 and ISO 12944. More

D

Deflection

How far a member bends under load. Often limited to a fraction of the span for comfort and finishes.

Dip transfer

Short-circuit MIG/MAG transfer at low current and voltage. Works in all positions. More

Dry film thickness (DFT)

The thickness of a paint or coating once dry, measured in microns. More

Duplex coating

Paint or powder coating applied over hot-dip galvanising, for colour and longer life. More

Duty cycle

The minutes out of ten a welding set can run at a given current before it needs to cool, shown as a percentage. More

E

Execution class (EXC)

A class from EXC1 to EXC4 in BS EN 1090 that sets the quality and inspection requirements for fabrication. More

F

Fillet weld

A triangular weld joining two surfaces at an angle, such as a T-joint or lap joint. More

Flange

The wide top or bottom part of an I-section or channel. More

Flat bar

Hot-rolled steel bar of rectangular cross-section, specified by width and thickness. More

G

Galvanising (hot-dip)

Dipping steel in molten zinc to give a bonded zinc coating, to BS EN ISO 1461. More

Gauge (SWG)

An old numbering system for sheet and wire thickness. 16 SWG is 1.626mm. More

Going

The horizontal depth of a stair step, measured nosing to nosing. More

Grade (steel)

The strength class of structural steel, such as S275 or S355, where the number is the minimum yield strength in N/mm². More

Guarding

A barrier that stops people falling from an edge, such as a balustrade or parapet. More

H

Handrail

A rail to hold for support on stairs and ramps, usually 900 to 1000mm above the pitch line. More

Headroom

The clear height above a stair or landing. 2.0m minimum in England. More

Helical stair

A stair that curves around a central open space without a central column. More

Hp/A (section factor)

Heated perimeter divided by cross-section area, in m⁻¹. Used to size fire protection. More

I

Infill

The panels or bars between the posts and rails of a balustrade. More

Intumescent coating

A fire protection coating that swells into an insulating char when heated. More

J

Juliet balcony

A balustrade fixed across a full-height opening, with no platform to stand on.

L

Lack of fusion

Weld metal that has not melted into the plate or the run below. More

Laminated glass

Two or more glass plies bonded with an interlayer, which holds the glass together if it breaks. More

Landing

A level area at the top or bottom of a stair flight, or between flights. More

Leg length (z)

The size of a fillet weld measured along each plate from the root to the toe. A '6 mm fillet' usually means a 6 mm leg. More

Line load

A load per metre along the top of a barrier, in kN/m, from BS 6180 or BS EN 1991-1-1. More

Low-hydrogen electrode

A basic-coated stick electrode, such as E7018, that gives weld metal low in hydrogen. Must be kept dry. More

M

Mass per metre

The nominal weight of a steel section per metre length, in kg/m. More

N

Nosing

The front edge of a stair tread. More

P

PFC

Parallel flange channel: a hot-rolled C-shaped section. More

Pitch (stair)

The angle of a stair from horizontal. 42° maximum for a private stair in England. More

Pitch line

An imaginary line joining the nosings of a stair flight. More

Porosity

Gas holes in a weld, often from damp consumables, lost shielding gas or dirty metal. More

Powder coating

A dry powder paint sprayed on and cured in an oven to form a hard finish. More

Preloaded bolt

A high-strength bolt tightened to a set tension so the joint resists slip by friction. More

Property class (bolt)

The strength class of a bolt, such as 4.6, 8.8 or 10.9, to ISO 898-1. More

R

RAL

A colour system of numbered standard colours, such as RAL 7016. RAL is a registered trademark of RAL gGmbH. More

RHS / SHS / CHS

Rectangular, square and circular hollow sections. More

Rise

The vertical height of a stair step. More

Root run

The first run of a multi-run weld, laid into the corner or root of the joint. More

RSJ

Rolled steel joist: strictly an I-beam with tapered flanges; often used loosely for any steel beam. More

S

Secondary steelwork

Smaller steel members supporting cladding, balconies, plant or finishes, rather than the main frame.

Spigot

A clamp that holds a glass panel at intervals instead of a continuous channel. More

Stringer

The inclined beam on each side of a stair that carries the treads.

Stringer bead

A straight weld run made without weaving. More

T

Throat thickness (a)

The design size of a fillet weld: the height of the largest triangle that fits in the weld. More

Toughened glass

Glass heat-treated to be much stronger than ordinary annealed glass. It breaks into small, blunt pieces. More

Tread

The part of a stair step you stand on. More

U

UB / UC

Universal beam and universal column: hot-rolled I and H sections with parallel flanges. More

Undercut

A groove melted into the parent plate along the toe of a weld and left unfilled. More

W

Weave

Moving the rod or gun from side to side while welding, to make a wider run. Used mainly for vertical-up welds. More

Web

The vertical part of an I-section or channel joining the flanges.

Welding positions (PA, PB, PF, PD)

ISO 6947 position codes: PA flat, PB horizontal-vertical fillet, PF vertical-up, PG vertical-down, PD overhead fillet. More

WPS

Welding procedure specification: the approved method for a weld, giving process, consumable, position and settings. More

Y

Yield strength

The stress at which steel starts to deform permanently, in N/mm². More

General guidance only, not design advice for a specific project. Building regulations guidance changes: check the current edition of each document, and get project-specific design from a competent engineer. Koyda Ltd accepts no liability for decisions made using this page.