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Project Fabrication & Erection
FABRICATION PROCEDURE
Structural steel fabrication can be carried out in shop or at the construction site.
Fabrication of steelwork carried out in shops is precise and of assured quality, whereas
field fabrication is comparatively of inferior in quality. In India construction site
fabrication is most common even in large projects due to inexpensive field labour, high
cost of transportation, difficulty in the transportation of large members, higher excise
duty on products from shop. Beneficial taxation for site work is a major financial
incentive for site fabrication. The methods followed in site fabrication are similar but the
level of sophistication of equipment at site and environmental control would be usually
less. The skill of personnel at site also tends to be inferior and hence the quality of
finished product tends to be relatively inferior. However, shop fabrication is efficient in
terms of cost, time and quality.
Structural steel passes through various operations during the course of its fabrication.
Generally, the sequence of activities in fabricating shops is as shown in Table. The
sequence and importance of shop operations will vary depending on the type of
fabrication required.
Sequence of activities in fabricating shops
| S.No. | Sequence of Operation |
|---|---|
| 1. | Surface cleaning |
| 2. | Cutting and machining |
| 3. | Punching and drilling |
| 4. | Straightening, bending and rolling |
| 5. | Fitting and reaming |
| 6. | Fastening (bolting, riveting and welding) |
| 7. | Finishing |
| 8. | Quality control |
| 9. | Surface treatment |
| 10. | Transportation |
ERECTION
Erection of steel structures is the process by which the fabricated structural members are
assembled together to form the skeletal structure. The erection is normally carried out by
the erection contractor. Generally the steps that are involved in the erection of steel
structures are shown in Table. The erection process requires considerable planning in
terms of material delivery, material handling, member assembly and member connection.
Proper planning of material delivery would minimise storage requirement and additional
handling from the site storage, particularly heavy items. Erection of structural steel work
could be made safe and accurate if temporary support, falsework, staging etc. are erected.
Before erection the fabricated materials should be verified at site with respect to mark
numbers, key plan and shipping list. The structural components received for erection
should be stacked in such a way that erection sequence is not affected due to improper
storing. Care also should be taken so that steel structural components should not come in
contact with earth or accumulated water. Stacking of the structures should be done in
such a way that, erection marks and mark numbers on the components are visible easily
and handling do not become difficult. From the earlier discussion it should emphasised
that safe transportation of fabricated items to the site, their proper storage and subsequent
handling are the pivotal processes for the success of fabrication of structural steel work.
Sequence of activities during Erection
| S.No. | Sequence of Operation |
|---|---|
| 1. | Receiving material from the shop and temporarily stacking them, if necessary. |
| 2. | Lifting and placing the member and temporarily holding in place. |
| 3. | Temporarily bracing the system to ensure stability during erection. |
| 4. | Aligning and permanently connecting the members by bolting or welding. |
| 5. | Connecting cladding to the steel structural skeleton. |
| 6. | Application of a final coat of painting. |