All the tubes, whose sections are determined according to the tension and compression forces as per the design calculations shall be seamed tubes produced from S235JR (St37-2), S275JR ( St44-2), S355J2G3 ( St52-3) quality steel sheets with high weldability property conforming to EN10025 standards.
| Steel Quality | Yield Stress | Tensile Stress | Elongation After Fracture |
|---|---|---|---|
| S235JR (St37-2) | 235 N/mm2 | 340-470 N/mm2 | 24% |
| S275JR (St44-2) | 275 N/mm2 | 410-580 N/mm2 | 20% |
| S355J2G3 (St52-3) | 355 N/mm2 | 510-680 N/mm2 | 20% |
Tubes produced in conformance with the DIN 2440, DIN 2441, DIN 1626, EN 10219 standards ranging from f26.9mm and f323.9mm diameter according to the design shall be used. Hot forged and/or machined cones of the same material quality of the tubes shall be welded on each end by semi automatic gas shielded arc welding process.
Nodes starting from f50mm diameter (f50,60,75,90,110,130,160,200,240,280,300,380...) shall be produced with C45 or AISI / SAE 1050 quality material in conformance with the EN 10083-2 standard, with hot forging in normalized condition and/or machining production techniques. Required bolt connection holes shall be drilled and tapped with digitally controlled drilling machines.
All bolts shall be produced with the materials in conformance with EN 10083-1 standard and shall have ISO metric treads conforming to DIN 13-1. Strength classification shall be 6.8, 8.8 or 10.9 in compliance with the requirements of EN ISO 898-1.
| Bolt Quality | Yield Stress | Tensile Stress | Elongation After Fracture |
|---|---|---|---|
| Space frame bolt 8.8 | 640 N/mm2 | 800 N/mm2 | 12% |
| Space frame bolt 10.9 | 900 N/mm2 | 1000 N/mm2 | 9% |
| Purlin system bolt 6.8 | 480 N/mm2 | 600 N/mm2 | - |
All sleeves shall be machined from hexagonal shaped cold and/or hot rolled S355J2G3 (St52-3) quality non-alloyed steel and/or AISI/SAE 1030 quality low alloyed steel.
Supports shall be produced with C45 or AISI / SAE 1050 quality material in conformance with the EN 10083-2 standard, with hot forging and/or machining production techniques. Required bolt connection holes shall be drilled and tapped with digitally controlled drilling machines. Support flanges shall be of S235JR (St37-2) material in conformance with EN 10025. Teflon plates with low friction coefficient shall be placed under the moveable supports.
a) Nodes and supports shall be electro plated with average 25 micron thick zinc in conformance with ISO 2081.
b) Bolts shall be coated with Delta Protect or Dacromet in conformance with ISO 10683, which consist of aluminum and zinc particles stocked in inorganic titanium and provides highest resistance against corrosion. This process meets the requirements of DIN 50021.
c) Tubes, purlins and purlin stools shall be sand blasted to meet the requirements of Sa 2 ½ in conformance with ISO 8504-2, and then shall receive electrostatic polyester powder coating of average 70-80 microns by means of robots and shall be baked in oven at 200 °C. If required, tubes and purlins can be hot dip galvanized in conformance with EN ISO 1461, EN 1179 prior to powder coating.
d) Sleeves shall be hot dip galvanized in conformance with EN ISO 1461, EN 1179.
As required by K.Span’s quality procedures and instructions, prior to erection, K.Span representative shall check the general site conditions and particularly the condition of the substructure on which space frame system is to be erected. All deviations from the approved shop drawings and all other unsatisfactory conditions to be brought to the attention of the Engineer. At the same time appropriate Contractor to be notified about the conditions detrimental to the proper and timely completion of the work and requirements necessary to correct them. Erection shall commence as soon as the unsatisfactory conditions are corrected.
Erection shall proceed in strict accordance with the manufacturer’s approved erection drawings and general “Work safety and workers health” regulations, under the supervision of K.Span representative. All bolts shall be tightened correctly in a way that no bolt will remain loose and there will be no slack in the connection. All the components of the space frame are prefabricated to match their position in the system and to be in true line and level with configurations as shown on the erection drawings. So, no force shall be placed on the member and the bolts shall not be forced during the erection to prevent secondary stresses. Temporary supports shall be placed to ensure the stability of space frame, as may be required during the erection according to the design controls of the erection sequences. Site welds of the supports shall be made by the experienced, educated and certified ( EN 287-1) welders of K.Span upon completion of the erection and arrangement of the support allowances for movement. Touch up paint work of the scratched and damaged surfaces shall be made with matching air drying touch up paint provided by the manufacturer.
Upon completion of all the erection woks, the space frame shall be handed over to the client with the “ Practical completion and hand over report” which is to be duly signed by the manufacturer and the client.
Quality system shall be guaranteed with ISO 9001:2000 within K.Span. International and national standards shall be referenced to K.Span quality system documents. Input and inter-control of space frame system main components shall be carried out according to related standards. At the end of the manufacturing, all of the certificates of applied analyses and tests shall be presented with project file.
K.Span, having welding qualification certificate according to EN 729-2, carries out welding with semi automatic gas shielded arc welding technique according to EN 729-2 standard's requirements. Non-destructive tests for all welded components shall be carried out by the welding co-ordination staff according to control methods mentioned in EN 288-3. Welding co-ordination staff shall be certificated according to EN 719, and welding operators shall be certificated according to EN 287-1. Mentioned non-destructive inspections are as follows;
| Instruction | Standard | Frequency |
|---|---|---|
| Liquid Penetrate Inspection | EN 571-1 | 1 Piece / Project |
| Macro Testing | EN 25817 | 2 Pieces / Month |
| Radiographic Inspection | EN 1435 | 1 Piece / 6 Months |
Incoming and intermediate controls of components used in space frame shall be carried out according to prepared instructions with defined frequency. During the all of these controls, tests mentioned in standards and being important to apply, shall be applied at in-house or independent external laboratories, and results shall be presented to client. Non-destructive tensile test with loads being 25% in excess of design capacity of tubes, that calculated with allowable stress design method shall be applied on the manufactured tubes. Tensile test shall be applied to all tubes of diameter 88,9 mm and higher, and to 50% of tubes of diameter 60,3&76,1 mm, and to 5% of tubes smaller than 60,3 mm.
Least required controls shall be mentioned below:
| Instruction | Standard |
|---|---|
| Tensile Test | EN 10002-1 | Hardness Test | EN ISO 6506-1, EN ISO 6508-1 |
| Chemical Analyses | EN 10025 (Tubes, Cone, Profile) EN 10083-1 (Bolt) EN 10083-2, ASTM A 29 (Node) EN 10025, ASTM A 29 (Sleeve) |
Coating Thickness Measurement | ISO 2081 ISO 10683 |
Tests of Painting | ASTM D 2794 ASTM D 3359 |
Compression Test | TS 206 |