Lesson 1Deadbolt types and dimensions: single-throw vs double-throw, bolt materials and typical diametersLooks at deadbolt designs for steel doors, comparing single-throw and double-throw types. Checks bolt materials, sizes, throw distance, latch guards, and matching with locks, strikes, and security standards used in Kenya.
Single-throw vs double-throw mechanismsBolt materials, hardness, and corrosionBolt diameter, throw length, and clearancesStrike plates, boxes, and reinforcementCompatibility with cylinders and escutcheonsLesson 2Corrosion protection options: galvanizing, paint systems, powder coat, surface prep standardsExplains how rust attacks steel doors, then compares galvanizing, liquid paint, and powder coating. Covers surface cleaning standards, coating thickness, checks, and picking protection to suit local weather and lifespan needs.
Atmospheric corrosion and exposure categoriesHot-dip galvanizing vs electro-galvanizingLiquid paint systems and zinc-rich primersPowder coating process and curing controlSurface prep grades per ISO and SSPCLesson 3Hinges and pivot hardware for high-use doors: butt hinges, continuous hinges, pin types, security hinge optionsLooks at hinge and pivot choices for busy steel doors. Compares butt and continuous hinges, pivot sets, pin and bearing types, security features, and sizing by door weight, usage, and fire or escape rules.
Butt hinge types, knuckle count, and sizingContinuous hinges for high-cycle applicationsFloor and top pivots for heavy doorsSecurity hinges, studs, and non-removable pinsBearing types, lubrication, and maintenanceLesson 4Fasteners and anchors to concrete: mechanical anchors, chemical anchors, anchor sizing and embedment depthsDescribes mechanical and chemical anchors for fixing steel frames to concrete. Covers checking base material, anchor sizes, embedment depth, edge distances, load paths, and fitting practices to stop loosening or cracks.
Concrete strength, cracking, and inspectionExpansion anchors and sleeve anchorsAdhesive anchors and curing conditionsEmbedment depth, spacing, and edge distanceTorque, installation, and pull-out testingLesson 5Standard steel profiles: rectangular tube, square tube, angle irons, flat bars—dimensions, wall thicknesses, and use casesDetails common hollow and solid steel shapes for door frames, stiffeners, and supports. Reviews size ranges, wall thicknesses, tolerances, and how shape choice affects strength, weight, and workshop making effort.
Rectangular and square hollow section rangesAngle irons for frames and edge stiffenersFlat bars for strike, hinge, and lock platesWall thickness vs load and weld distortionSpecifying tolerances and mill certificatesLesson 6Materials selection checklist for warehouse entrance doors (weight, security rating, cost)Gives a handy checklist for choosing materials for warehouse entry doors. Balances weight, security level, rust resistance, fire and exit needs, fittings match, and full setup and long-term costs.
Door leaf gauge, profiles, and reinforcementsFrame type, anchors, and substrate checksLocking, cylinders, and access controlCorrosion protection and environment classBudget, lifecycle cost, and maintenanceLesson 7Standard cylinder lock types for metal doors: euro-profile, rim cylinder, tubular, mortise cylinders—dimensions and backsetCovers main cylinder types for metal doors, like euro-profile, rim, tubular, and mortise. Explains size standards, backset, cam types, keying choices, and fit with multipoint and panic fittings.
Euro-profile cylinder dimensions and camsRim cylinders for surface-mounted locksTubular cylinders and keyway optionsMortise cylinders and thread standardsBackset, center distance, and door prepLesson 8Sheet thickness selection for door leafs and frames: 1.5–6 mm ranges, tradeoffs between weight and securityGuides picking sheet thickness for door panels and frames from 1.5–6 mm. Discusses stiffness, dent resistance, weight, hinge load, and security, with common thicknesses for industrial, fire, and high-security doors.
Typical gauge ranges for leaves and framesDeflection, dent resistance, and span limitsWeight impact on hinges and closersSecurity, burglary, and fire rating needsCost and fabrication implications by gaugeLesson 9Common structural steels for doors: S235, S275, mild steel properties and selection criteriaIntroduces everyday structural steels for doors like S235, S275, and mild steel. Discusses yield strength, weldability, toughness, coating fit, and picking grades for frames, panels, and support plates.
Mechanical properties of S235 and S275Mild steel chemistry and weldabilityFormability for bends, hems, and profilesCoating performance and galvanizing issuesSelecting grades for frames and stiffeners
