Steel Fabrication

Steel fabrication is the building of structures or frames by cutting, bending and assembling processes. It is a value added process that involves the construction of machines and structures from various types of steels such as MildSteel , Stainless Steel etc. The frame generally uses readily available standard sections that are purchased from the steel maker or steel stockholder, together with such items as protective coatings and bolts from other specialist suppliers. Most modern steelwork fabrication factories have computer aided design and detailing (CAD) which is linked directly to factory floor computer numerically controlled (CNC) machinery creating a genuine CAD/CA environment. The accuracy of the computer generated details being transmitted directly to the computer aided manufacturing (CAM) machinery increases the quality standards of production.The fact that machinery has taken over from the tape measure means that the frame is produced to high quality standards which are reflected in the speed and accuracy of steel erection on site. Due to its versatility, there are a wide range of stainless steel fabricating techniques. Although it has relatively high strength and work hardening rates, stainless steel is malleable enough to be bent,folded, machined, welded, deep drawn, or spun. The most common three stainless steel fabricating processes are& work hardening, machining, and welding.

CNC Machine

CNC Machining is a process used in the manufacturing sector that involves the use of computers to control machine tools. Tools that can be controlled in this manner include lathes, mills, routers and grinders. The CNC stands for Computer Numerical Control.Under CNC Machining, machine tools function through numerical control. A computer program is customized for an object and the machines are programmed with CNC machining language (called G-code) that essentially controls all features like feed rate, coordination, location and speeds. With CNC machining, the computer can control exact positioning and velocity. CNC machining is used in manufacturing both metal and plastic parts. First a CAD drawing is created (either 2D or 3D), and then a code is created that the CNC machine will understand. The program is loaded and finally an operator runs a test of the program to ensure there are no problems. This trial run is referred to as "cutting air" and it is an important step because any mistake with speed and tool position could result in a scraped part or a damaged machine.The process is more precise than manual machining, and can be repeated in exactly the same manner over and over again. Because of the precision possible with CNC Machining, this process can produce complex shapes that would be almost impossible to achieve with manual machining. CNC Machining is used in the production of many complex three-dimensional shapes. It is because of these qualities that CNC Machining is used in jobs that need a high level of precision or very repetitive tasks.

In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs.A series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design. CNC-like systems are now used for any process that can be described as a series of movements and operations.

These include laser cutting, welding, friction stir welding,ultrasonic welding, flame and plasma cutting, bending, spinning, hole-punching, pinning, gluing, fabric cutting, sewing, tape and fiber placement, routing, picking and placing, and sawing.

Architectural Steel Works

Modern building and structure designs require aesthetic appearance and extended life. As a result stainless steel, once the preserve of prestige projects, is becoming an everyday material due to its strength, corrosion resistance, appearance and sustainability. Typical applications Stainless steel is a favorite of architects designing the world’s tallest buildings, the longest bridges, and the most popular public arts projects.Some applications are highly visible and stainless steel is both aesthetic and functional, such as curtain wall and roofing. Others are practical, safety related and sometimes hidden, like masonry and stone anchors, bollards and safety railings..In applications with coastal or deicing salt, industrial pollution, volcanic or other corrosive environment exposure, a molybdenum-containing stainless steel with a smooth surface finish is needed unless frequent cleaning is acceptable.Stainless steel is specified where long life, low maintenance, and aesthetic appeal are critical, including:

Stainless steel provides a wide range of benefits for architectural and construction projects including:

Aesthetic appeal and inherent long-life resistance to high heat, corrosion, pitting, and stress corrosion cracking cost-savings on initial material and over the lifecycle of the project extended lifespan and reduced maintenance for concrete construction where corrosion is a concern maintenance free with a minimum increase in investment cost

Structural Steel Erection

Steel erection involves positioning, aligning and securing the components on prepared foundations to form a complete frame.

Steel erection consists of four main tasks:

• Establishing that the foundations are suitable and safe for erection to commence.
• Lifting and placing components into position, generally using cranes but sometimes by jacking. To secure components in place bolted connections will be made, but will not yet be fully tightened.
• Aligning the structure, principally by checking that column bases are lined and level and columns are plumb. Packing in beam-to-column connections may need to be changed to allow column plumb to be adjusted.
• Bolting-up which means completing all the bolted connections to secure and impart rigidity to the frame Careful planning is necessary to realise the advantage of speed offered by steel construction. There are three main planning factors that affect the buildability of the scheme. These are:
• Practical erection sequence. The location of bracing or other means of maintaining structural equilibrium are crucial here.
• Simplicity of assembly. Simply-assembled connections are the main factors here.
• Logical trade sequences.

The principle is to establish a stable unit as quickly as possible, and to attach subsequent elements directly or indirectly to this.

Maintenance Of Structures

Structural Considerations

The repair method will restore the steel structures to the desired strength and that the most effective method of repair has been chosen. Load-carrying members are usually replaced when 30% or more of the steel has been lost by corrosion or when they are deformed. A stressed member should not be removed before the stress has been relieved by transfer of load to adjoining members or by new temporary members and adequate bracing. In the replacing of piles, the load should be shifted temporarily to other piles by struts or beams using jacks. The replacement of wales on quay walls may require excavation of fill to relieve lateral loads. In some cases, it may be more economical or practical to strengthen existing members than to replace them. This is especially true where corrosion is serious in only a limited area.

Steel piling may require coating protection or there may be some Those requiring cathodic protection should.

Reinforcement of H-piling by welding steel plates onto flanges and web may be appropriate in localized areas of corrosion, such as the tidal zone. The reinforcing plates should be of sufficient thickness to restore the original strength to the piling and of sufficient area to encompass and extend beyond the extremities of the corroded area

Sheet piling usually serve as a bulkhead to retain fill. Thus, extreme care must be taken during replacement of one or more piles to prevent failure and passage of fill through the opened spaces into the water.

Steel supporting components (Wales, braces, etc.) should be repaired or replaced, as necessary.

MOORING FITTINGS

Maintenance of mooring fittings (bitts, bollards, cleats, chocks, etc.) includes tightening or replacing bolts; replacement of cracked, broken or badly corroded fittings; and reinforcement or replacement of foundations.

FLOATING STRUCTURES

Repair of holes in the sides of floating structures, such as floating, lifts, and camels, should be made by welding on steel plates.