Workshop Fabrication

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Fabrication Man-hours 

  • Fabrication man-hours are determined by the quantity of hours/tasks in each steel assembly, for example, each column, beam, brace, assembly, or bracket.
  • The average constants are for high repetition portal frame and high rise type work. The ranges are for differences in piece size, detail, repetition, and fabrication methods.
  • These constants are based on conventional fabrication methods used by most fabricators, ie manual gas cutting and magnetic broach drilling, and semi-automatic "mig" or "flux core" welding.
  • With semi-automated saw and drill lines output is much higher but machine costs are higher, and generally the market does not differentiate costs because semi-automation affects only part of overall fabrication.
  • The constants include for reading fabrication drawings, stacking and sorting materials, marking out, turning, grinding edges and welds, operator setting up, servicing gear such as welders and grinders, and QA including average rework.
  • These constants are "whole of job", and hence will differ from spot check times which will not be representative of a complete job due to the tendancy not to include downtime and variances in productivity.
  • Repetition affects productivity in different ways, and for some labour operations can have a significant impact on output, while other labours produce only slight improvements. A high degree of difficulty can also have a large impact on output, for example, very detailed drawings, angled assembly, low repetition of detail, complex set out.

 

Description Tasks     Average Range (Min-Max)
Plates, brackets, and fly braces          
  Prepare plate connections, cleats and stiffeners, rectangular   piece 4.5 min 3-6 min
  shape ex flat bar, not exceeding 300mm wide or 16mm        
  thickness; guillotine to size and punch holes, using hydraulic        
  ram punch and shear machine.        
  Same as last but irregular shape ex plate, or exceeding   piece 9 min 6-30 min
  300mm wide or 16mm thickness; cut to size and form holes—        
  punch and shear, flame cut, or drill equipment.        
  Prepare angle brackets or fly braces not exceeding 1.5m long;   piece 9 min 6-12 min
  guillotine to length and punch holes—using punch and shear.        
  Slotted holes in maximum 20mm plate or angle—punched and   slot 7.5 min 6-10 min
  flame slotted.        
  Mark and tack plate connections, cleats and stiffeners in   No 6.5 min 5.5-7.5 min
  position on beams, columns etc, square and not exceeding        
  400mm length.        
  Same as last but bracing cleats, plates 400mm to 1000mm   No 12 min 8-15 min
  length, or hip rafter plates etc.        
Cutting sections          
  Cut secondary sections, up to 150mm—angles, PFCs, HS   piece 15 min 12-20 min
  Extra Value for each end mitre cut, or notch cut   end 6 min  
  Extra Value straight join including prepare and vee butt weld   join 1.0 hr  
  Cut sections to length, up to 310 UB/UC/PFC/HS   piece 28 min 26-30 min
  Extra Value for each end mitre cut, or notch cut   end 12 min  
  Extra Value cut and form taper end, approx 300mm long   end 45 min  
  Extra Value straight join including prepare and vee butt weld   join 2.5 hr 1.5-3 hr
  Cut sections, over 310 UB/UC/PFC/RHS   piece 40 min 35-55 min
  Extra Value for each end mitre cut, or notch cut   end 15 min  
  Extra Value cut and form taper end, approx 500mm long   end 72 min 60-80 min
  Extra Value straight join including prepare and vee butt weld   join 4.5 hr 3.5-5.5 hr
Labours to all sections          
  Drill bolt holes in structural sections   hole 6.5 min 4.5-7.5 min
  Form slotted bolt holes in structural sections   slot 15 min  
  Gas cut and grind edges for cut outs, penetrations, straight   metre 20 min  
  Same as last, circular   metre 30 min  
  Assemble and tack portal frame knee, apex, or k-brace join   join 1.25 hr 1-1.5 hr
  Assemble secondary section frame joins   join 30 min 20-45 min
  Precambering; up to 310 UB or UC   No 2.5 hr 1-3 hr
  Precambering; over 310 UB or UC   No 3.5 hr 3-6 hr
  Cut, prepare and assemble corbels, tapers, haunchings etc   No 1 hr 0.75-2 hr
  max. 1m long        
  Assemble composite members, e.g. crane beam channel onto   metre 30 min  
  UB        
  Truss cutting and assembly        
  Cut truss diagonals and struts   piece 12 min 10-15 min
  Extra Value mitre cut or notch ends   end 7.5 min 6-9 min
  Cut, prepare, join and weld chord, maximum 250 PFC or UB   chord 1.5 hr 1.25-2 hr
  x 12m long        
  Mark out and set up jig for truss assembly x 12m long   No 4 hr 3-6 hr
  Assemble truss top and bottom chords with diagonals and   truss 4 hr 3-6 hr
  struts x 12m long, in jig        
  Extra Value to precamber truss, x 12m long   No 2 hr 1-3 hr
Diagonal bracing          
  Diagonal bracing rod cut, join, assemble turnbuckles, threaded   No 40 min 20-60 min
  ends        
  Diagonal bracing angle cut, join, drill bolted ends   No 50 min 30-75 min
  Welding—80% downhand, 20% vertical        
  5 and 6mm fillet weld   m 18 min 15-22 min
  8mm fillet weld—2 runs   m 32 min  
  10mm fillet weld—3 runs   m 46 min  
  12mm fillet weld—4-5 runs   m 72 min  
  Vee prepare end of UB, UC, PFC, HS for butt weld, max   end 8 min  
  300mm depth        
  Same as last, over 300mm   end 12 min  
  Vee butt weld up to 12mm   m 90 min  
  Vee butt weld over 12mm, up to 16mm   m 150 min  
  Extra Value for backing strip to joins in SHS   join 7.5 min  
  Extra Value for backing strip to joins in CHS   join 30 min  
  Hit and miss stitch 6mm fillet weld   m 10 min  
Miscellaneous          
  H.D. bolt assembly into pairs   pairs 6 min  
  Unload and stack inwards steel, and load out fabricated steel   tonne 1.5 hr 1.25-2 hr
  onto trucks        
Productivity factors—against the constants above        
  General: market, complexity or regional     0.85-1.33  
  Site fabrication and welding     2.00-4.00  

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