11,Kubera Estate,408/14 CTS 10, Gultekdi Road, Veer Savarkar nagar, Pune: 411037 ( India )
Tel : +91 20 24268982,
020 - 24264589
Fax : +91 20 24272835
E-mail : composites@aefl.in
Applications
- Plating Industry
- Outdoor Works Area
- Chemical Plants
- Desalinization Plants
- Marine
- Fertilizer
- Pulp & Paper
- Defence
- WasteWater Treatment
- Cooling Towers
- Food Processing
- Mining
- Offshore & Onshore App.
- Power Plants
- & many more
Welcome to Composite Division
Achievements
Pultrusion
The construction of the tower is cantilever type and hence there were large twisting moments in most of the main and cross members. This meant that the profiles had to have a good torsional resistance. The best profile for this job was round tube as it has good torsion resistance and the least wind resistance. However the round tube is not well suited for joinery. The second best option was a square tube. The profiles selected for the tower were square tubes of varying sizes and thickness based on the actual stress conditions on the Tower. The main members of the Tower were
- Main member - Square tube 150 x 150 mm. Wall thickness - 8 mm, 10 mm.
- Cross member - Square tube 110 x 110 mm. Wall thickness - 6 mm.
- Diagonal member - Square tube 75 x 75 mm. Wall thickness - 6 mm, 8 mm.
the various wall thicknesses were rationalized to only one thickness per profile for faster production. All profiles were provided with large corner radius to reduce the wind resistance of the profile. The torsional resistance of the profile was further improved by incorporating a +/- 45º stitched mat on the inner and the outer surfaces of the tube. The balance material was the standard combination of roving and mats.
As the tubes were specifically manufactured for this tower, the dies and mandrels were manufactured and chrome plated in-house using our electroforming unit's facilities. During pultrusion, the job lengths were also set dynamically when the tubes were under going pultrusion to prevent re-cutting and wastage. Each section of tube coming out of the machine was marked and numbered as per the fabrication drawing. Additional lengths were provided on some members at regular intervals to take test coupons for tensile testing.
Fabrication
The fabrication had a difficulty of it's own as the client wanted to inspect the fabricated tower before it was allowed to be shipped to site. The massive size of the tower also meant that it could not be shipped in a fabricated condition.
The solution to that was to assemble the four faces of the tower in the factory. Demonstrate the fabrication by assembling the smaller section i.e. top portion of the tower in the factory for client's inspection. Then disassemble the tower for shipping and re-assemble it on site. The sides of the tower were 45 mtr. long and 14 mtr. wide. To accommodate the entire tower on our shop floor, two pultrusion lines had to be temporarily shut down and kept aside so that the space can be utilized for this job. The photograph of the assembly process is self-explanatory.
When the pultrusion was complete, life sized joints were prepared for testing and put on the universal testing machines until failure to confirm that they would survive the worst case conditions, and that too with a margin to spare.
When fabrication was completed, each section including the gusset plates were numbered, dissembled and packed for transport.
Testing and process control
The testing of the tower was done at the following stages
- Raw materials : A strict control over the raw materials was exercised. The basic areas of control were the resin, and the adhesive. Glass and mats have a very high degree of standardization and hence manufacturers certifications were accepted
- In process : Glass placement and degree of cure were the prime areas of inspection.
- Fabrication : The testing during fabrication mainly involved around testing the tensile strength of the pultruded section, Lap shear strength of the adhesive under different bonding conditions and finally token testing of joints at full scale.