Fabrication work steps and activities are defined depends upon on the scope of tank components, type of materials and necessary inspection. Suppose a process tank prefabrication scope includes
,the following components
Tank body )1( External components attached to tank shell)2( Man-ways on shell side and roof side Inlet and outlet pipe nozzles bottom drain pipe Internal components )3( Skimming box
,Stilling Wells & Level Gauge Internal Spiders Tank Access Steel Work )4( Spiral Staircase Top Roof Platform Accessories, Transport Saddles and Lifting Beam to facilitate lifting work )5( Assume that material for tank body, internal parts, man-ways and nozzles are stainless steel, and for
.staircase, tank roof platform and bottom drain pipe are carbon steel material Activity and work steps for tank body fabrication )1( a) Base Plate( Marking and cutting Tacking and welding PMI Testing Removal of backing plate Vacuum box test welds Erect Scaffold for access
)b) Shell Plate Fabrication (1st Course ( Marking and cutting
Rolling of plate Setting and tacking joint to base plate, vertical joint Full welding Holding down plates installation
)NDT Joints (DPI, RT PMI Inspection
)c) Shell Plate Fabrication (2nd Course ( Marking and cutting Rolling of plate Scaffolding installation Setting and tacking joint to 1st course and vertical joint Full welding
)NDT Joints (DPI, RT PMI Inspection
)d) Shell Plate Fabrication (3rd Course( Marking and cutting Rolling of plate Scaffolding installation Setting and tacking joint to 2nd course and vertical joint Full welding
)NDT Joints (DPI, RT PMI Inspection
)e) Shell Plate Fabrication (4th Course ( Marking and cutting Rolling of plate Scaffolding installation Setting and tacking joint to 3rd course and vertical joint
Full welding
)NDT Joints (DPI, RT PMI Inspection
)f) Shell Plate Fabrication (5th Course ( Marking and cutting Rolling of plate Scaffolding installation Setting and tacking joint to 4th course and vertical joint Full welding
)NDT Joints (DPI, RT PMI Inspection
)h) Shell Plate Fabrication (6th Course( Marking and cutting Rolling of plate Scaffolding installation Setting and tacking joint to 5th course and vertical joint Full welding Rolling of curb angle Setting, tacking and full welding of curb angle Roof plate clip installation
)NDT Joints (DPI, RT PMI Inspection
.Note. Nos. of course would be different depending on size of tank and how you define i) Roof Work( Marking and cutting of roof ring plate, rafter, braces and roof clips Welding of roof ring plate, rafter and braces Marking and cutting of roof plate
Fit up and welding of roof plate PMI test Vacuum box test welds Position and bolt up Roof to tank body Full welding of roof to curb angle PMI Test Activity and work steps for external components fabrication )2(
a) Man-ways( Marking and cutting of plate and reinforcement plate Rolling and welding of man-way plate Fabrication of flanges, hinges, handles and cover Assembly of cover, handles and hinges Fabricate reducing flange Marking and cutting of man-ways in tank shell Marking and cutting of man-ways in roof Fit up and welding of man-ways in tank shell Fit up and welding of man-ways in roof Installation of reinforcement pads in tank shell Installation of reinforcement pads in roof PMI test Pressure test reinforcement pad b) Inlet and outlet pipe nozzles ( Marking and cutting of pipe and reinforcement plate Fabrication of nozzles
)NDT Joints (DPI Marking and cutting of nozzle location
Fit up and welding nozzle PMI test Installation of reinforcement pad PMI test c) Bottom Drain Pipe( Marking and cut to length Tack and welding joints PMI Test
)NDE Testing (DPI, RT Modify bottom drain and piping support
)NDE Testing (DPI, RT Hydrotest of drain line Painting work Activity and work steps for internal components fabrication )3(
a) Skimming Box( Marking and cutting Assemble skimming box Rework Skimming Box Fit up and welding inside tank PMI test b) Stilling Wells and Level Gauge ( Marking and cutting of pipe and frames Pipe drilling holes Fabricating of support frames Fabricate stilling wells and level gauge
)NDT Joints (DPI, RT
Fit up and welding of support frame Positioning of stilling wells and level gauge PMI test c) Internal Spiders( Marking and Cutting Roll end plate Fit up & welding of support clip PMI test Assemble internal spider NDE Testing Fit up to tank Activity and work steps for Tank Access Steel Work Fabrication )4( a) Spiral Staircase( Rolling of stringers Marking & Cutting of length material, support clips Fit up & welding of support clips PMI test Assembly of spiral staircase Assembly of handrail NDE Testing Trail fit to tank shell Disassembling Galvanizing Packing Delivery
)b( Top Roof Platform
) Rolling of structure ( angle Marking & Cutting of length material, support clips Fit up & welding of support clips PMI test Assembly of top platform Assembly of handrail NDE Testing Trail fit to tank roof Disassembling Galvanizing Packing Delivery Lifting Accessories )5( a) Transport Saddles( Marking and Cutting Assembly of saddles Fit up & welding of saddles NDE Testing PMI test b) Lifting Beam( Marking and Cutting Assemble lifting beam NDE Testing Certification of lifting beam Painting of beam Note: NDE= Non Destructive Examination PMI= Positive Material Identification
)DPI= Dye Penetrant Inspection/Liquid Penetrant Inspection (LPI Finally, most of the activities covered in this post would help you in developing a production
.schedule
