BY Steel Structure Group

Material purchase

Materials must be purchased in accordance with the requirements of the drawings and the check list

● Check list

● Material purchase order

★ Supply Department

▲Technical Department

Material acceptance control

Confirm the size, quantity and identification of the materials against the incoming material list, and submit the material certificate

● Incoming material list

● Material certificate

★ Material Department

▲Supply Department

Material identification

Classify steel plates according to relevant standards and requirements, and make identifiable marks.

★ Material Department

▲ Production Department

 Material quality inspection

● Shape & size

● Chemical composition

● Mechanical performance

● Ultrasonic testing for steel plates with thickness greater than 30mm

References：

● Dimension, shape, weight and tolerances for hot-rolled steel plates and sheets

● Dimension, shape, weight and tolerances for hot-rolled steel bars

● Hot rolled section steel

● Seamless steel tubes for structural purposes

● Steel and steel products--Location and preparation of test pieces for mechanical testing

● Cold-formed steel hollow sections for general structure--dimensions, shapes, weight and permissible deviations

● Design and contract-related requirements

● Incoming inspection notice for purchased parts

● Material certificate

● Inspection records of incoming raw materials

● Re-inspection report of raw materials

★ Quality Control Department

▲ Supply Department

Part blanking

According to the technical requirements of the drawings, cut the materials according to the corresponding materials.

● Part drawings and process

★ Cutting workshop

▲ Technical Department

Part identification

Make identifiable marks on the parts and record the information of the materials used for the parts.

● Use records of raw materials for on-site blanking of parts

★ Cutting workshop

▲ Production Department

Part inspection

Item

Tolerance

● Part drawings and process

● Steel structure parts processing inspection records

◆ Production work sheet

★ Quality Control Department

▲ Cutting workshop

Part length and width

±3

Part length, width and diagonal

3

Flatness of cutting surface

0.05t, and should not be greater than 2

Local notch depth

1

t is the thickness of the plate, unit: mm; the position, size and roughness of the groove shall meet the requirements of the drawings

Part hole making and inspection requirements

Bolt hole pitch range

≤500

501～1200

1201～3000

﹥3000

● Part drawings and process

● Steel structure parts processing inspection records

◆ Production work sheet

★ Quality Control Department

▲ Cutting workshop

Distance between any two holes in the same group

±1

±1.5

—

—

Distance between holes in two adjacent groups

±1.5

±2

±2.5

±3

The hole diameter deviation and roughness shall meet the technical requirements of the drawings, the hole edge is not damaged, and there is no burr and flash.

Work preparation

Welding procedure qualification

Develop and implement a list of welding procedures that are in line with the project. The list must state the limits of the basic parameters of each welding process, including: welding process number, plate thickness range, groove form, welding method, welding position, welding parameters of each layer, etc.

● Welding process instruction

● Welding procedure qualification report

★ Technical Department

▲ Production Department

▲ Quality Control Department

Welder qualification

Arrange qualified welders to perform the work, and make a record

● Welder List

● Welder Certificate

▲ Production Department

Assembling works

● Assembling should be carried out according to drawings and process requirements to ensure dimensional accuracy

● Assembling gap should meet the requirements of drawings and related standards

● Position welding should meet the process and related requirements

● Cleaning of cutting slag and debris and welding bead grinding

● Identification of the components after the assembling is completed

● The unmarked size and shape tolerances of the components shall meet the relevant standards and requirements

● Drawings and process

● Operation Instruction

★ Riveting workshop

▲ Technical Department

Inspection before welding

● Check whether the assembled dimensions of the components meet the requirements

● Check whether the groove type and root gap are in line with the welding process

● Check the grinding condition of the weld bead

● Check the quality of tack welding

● Drawings and process

● Operation Instructions

● Assembly inspection records of structural parts

◆ Production work sheet

★ Quality Control Department

▲ Riveting workshop

Welding operation and process inspection

● Welder qualification must meet the requirements

● The use of welding material must match the base material

● Check the welding parameters according to the welding process

● Evaluate the stability of the welding method and weld formation

● Check preheating before welding and insulation between layers

● Check welding anti-deformation measures

● Welding process instruction

● Welding process inspection record

★ Riveting workshop

▲ Quality Control Department

Inspection after welding

● According to the GB/T19418-2003 Arc-welded joints in steel-Guidance on quality levels for imperfections, check whether the weld has defects that exceed the standard. Eliminate obvious defects such as cracks, arc craters, weld bumps, pores, etc.

● Whether the size of the weld is consistent with the drawing and the appearance of the weld is formed.

● Splash removal

● All welding spots of the base metal should be cut and polished after welding.

● 1mm All edges are rounded, the minimum radius is 1mm.

● All craters and scars need to be polished, and the depth of polishing and repair should not exceed 7% of the plate thickness.

● Welding appearance inspection record

◆ Production work sheet

★ Quality Control Department

▲ Riveting workshop

Non-destructive testing

Magnetic particle inspection

Ultrasonic testing

Radiographic inspection

● Refer to 4.3 to find Non-destructive testing content

● The quality level of each weld is specified in the drawing

● Non-destructive test report

● Non-destructive testing equipment verification certificate

★ Quality Control Department

▲ Technical Department

Non-destructive testing personnel

● Certificate of non-destructive testing personnel

★ Quality Control

Non-destructive testing content

1）One film for each cross weld

2）The tube butt film must include the starting point. If the start and end points cannot be identified, then the tube will be connected for 100% filming

3）If the defect cannot be determined by the inspection, then radiographic inspection must be carried out

4）Unless the defect cannot be determined by ultrasonic inspection, radiographic inspection is not required

Weld repair

● All welds must be repaired in accordance with the feasible rework welding process under the guidance of technicians. After the defects are treated in the full penetration welds, magnetic particle inspection must be carried out to ensure that the defects have been removed.

● During rework, the preheating must be increased by 50 degrees Celsius

● The non-destructive testing range of the rework area is increased to 100%, and the rework tip is increased by 200mm. If the extension test finds additional defects, then the entire weld must be inspected

● Without the consent of the technical department or the owner, no more than 2 repairs in the same place are allowed.

● Welding repair process

● Welding repair record

★ Technical Department

▲ Quality Control Department

Surface protection/surface treatment

The primer, spray paint process, and topcoat color in each project or contract must be approved by the owner. If there is no other statement in the contract, the following requirements should be followed:

● Sand blasting reaches Sa2.5

● 45μm zinc-rich ethyl silicate workshop primer

● 40μm epoxy resin or epoxy primer

● 40μm epoxy resin or epoxy topcoat

a. The contract have no additional requirements for the above treatment. Except for the inside of the box, the surface needs 45μm epoxy resin or epoxy primer. The said 45μm does not include the thickness of the shop primer.

b. Before cutting and assembling, the sandblasting surface and workshop primer spraying should be carried out.

c. The paint process must be approved by the owner before the surface pretreatment.

● Painting process

★Technical Department

Control and inspection

Before surface protection

● Ensure appearance control and non-destructive testing, and the necessary repair work has been completed

● Remove all sharp corners, no splash on the surface

★ Quality Control Department

▲ Riveting workshop

Inspection before shot blasting

● Check the part identification

● Check if there are stains on the surface

★ Shot blasting section

▲ Quality Control Department

Before painting

Examination：

● Sand blasting of all sections reaches Sa2.5

● Make sure the surface is clean, whether there are oil stains and sundries

● Whether the areas that do not require sandblasting and painting are protected

● A data sheet is available, and painters should be familiar with the data sheet

● The paint ratio should be carried out in accordance with the product manual

● The equipment functions normally

● The temperature of the steel plate is at least 3 degrees Celsius above the dew point

● Ambient temperature above 5 degrees Celsius

● Record the manufacturer, production batch and color of the paint used to prepare the painted parts or components

◆Production work sheet

● Surface treatment inspection record

★ Quality Control Department

▲ Painting section

Paint spray inspection

● The appearance of the paint film on the surface of the component should not be mis-coated or missed, and the coating should not peel off and return to rust. The coating should be uniform, without obvious wrinkles, dripping, pinholes and bubbles, etc.

● Check the thickness of the paint film according to the specification

● Perform the detection of paint film adhesion according to the current national standard GB1720 "Determination of Adhesion of Paint Films" or GB9286 "Paints and varnishes-Cross cut test for films ".

● Paint spraying inspection record

◆ Production work sheet

★ Quality Control Department

▲ Painting section

Trial assembly

During the trial assembly, all components must be marked in accordance with the drawings for easy identification at the assembly site, and a numbered drawing that can identify all components must be prepared.

After all welding is completed, all bolts and joints are tested in accordance with the drawings to imitate the actual operating state before the surface treatment. The main connections must be filed in the form of photos, which show tolerance, rotations, angle deviations, etc. Focus on the following points of control:

● Overall camber

● The adhesion rate and perforation rate between the upper and lower main beams and the flange plates of the connecting beams

● Dimensional accuracy of length, width, and height of the main beam, and the diagonal difference of the section.

● Advance the track gauge deviation and the deviation of track center and web center to meet the requirements

● The coaxiality of the main beam and the guide beam rotation hinge and the assembly gap

 Please refer to the inspection guide for specific requirements

● Numbered drawing

● Photos

● Pre-assembly inspection record

★ Quality Control Department

▲ Technical Department

▲ Production Department

Final check

All documents and production drawings must be checked, and the unqualified items that need to be rectified on the documents or products are in a separate rectification list.

All technical, contract clarification, and inconsistency approvals must be recorded. Relevant identification and marking shall be carried out in the relevant position of the drawing.

● Rectification list

● Technical clarification

● Inconsistency report

● General production drawings and general description

★ Quality Control Department

▲ Technical Department

▲ Production Department

★ Organizer    ▲ Co-organizer    ◆ Checkpoint