PMt Boilers Section
Internee No: I-0926
Duration: 09-08-2011 to 05-09-2011
Supervisor: Mr. Umar Jalil
Contents Acknowledgement 4 Abstract 5 Introduction 6 DESCON vision 6 Manufacturing Units 6 Sectors 6 Major Projects 7 Departments of DESCON 8 Production departments Layout shop 8 Machine shop 11 Manufacturing process - Boilers 15 - Pressure vessels 19 - Heat exchangers 20
- Heat Recovery Steam Generation (HRSG) 23
- Piping 24
- Welding processes 25
Shielded metal Arc Welding (SMAW) 26 Submerged Arc Welding (SAW) 27 Gas Metal Arc Welding (GMAW, MIG) 28 Gas Tungsten Arc Welding (GTAW, TIG) 29 Flux Cored Arc Welding (FCAW) 30
- Welding positions 31
- Welding Joints 32
- Welding symbols 33
Sand blasting 36
Non destructive testing (NDT) 40 Methods
- Radiographic test (RT) 40
- Ultrasonic test (UT) 41
- Penetrant test (PT) or Die penetrant test (DPT) 43 - Magnetic test (MT) or Magnetic particle test (MPT) 45 Applications of Non Destructive Testing 46 Quality Assurance & Quality control (QA & QC) 47
Codes & Standards 49
Roles / Functioning 50
Allah almighty the owner blessed His creation with all those things which are in His creation’s interest and it requires His creation’s devotion to Allah Almighty. I thank Allah for all those blessings which He bestowed me on every occasion throughout my life. Being a student in the field of Mechanical Technology Recently I am blessed with an opportunity to learn in the gorgeous working environment of DESCON Engineering Ltd. under the kind assistance of its well mannered and experienced personnel. Mr. Umar Jalil, Mr. Rana Naeem and Mr. Muhammad shafique has been a constant source of inspiration, encouragement and, occasionally, enforcement, as deadlines approach to seek the implementation and to analyze the knowledge which I acquire during studying in my university. I pay my gratitude to all these and those whom directly or indirectly assist me over the span of internship.
In last I salute university management to give me opportunity to work and get knowledge from the great professional environment of DESCON to broaden my vision.
Within my educational program at the University of Engineering and Technology Lahore, I was given the opportunity to complete my internship in the DESCON Engineering (PVT) Limited and gather besides practical experience in the area of fabrication, many valuable skills and practical knowledge was gained during internship duration. Throughout internship many assignments were assigned to me by my supervisor in order to implement my theoretical knowledge into practical field such as Study of design, sandblasting, galvanizing & furnace, flanges, non-destructive testing, hydro testing, and paint. The course of action adopted to complete these activities was to first understand the assignment on hand then understanding the purpose of the assignment then knowing how to do the required task in most efficient way. These activities were done according to the requirements of the supervisor and if there were any problems in doing the task then I contact the supervisor to help me in that assignment. After completing the required task the findings were presented to the supervisor for its evaluation. I spent most of the time in field to observe the fabrication and inspection process.
In 1977 to fulfill the need of Engineering Services a company was established from the name of DESCON which stand for Design Engineering Services Construction and Commissioning. Today DESCON is a major player in the region serving the oil and gas, chemical, petrochemical, cement, power and infrastructure sectors in Pakistan and the Middle East. The integrated package of services encompasses engineering, procurement, manufacturing, construction, commissioning and maintenance.
Descon's Headquarters is located in Lahore, Pakistan. After providing the services in Pakistan Company started to provide Engineering Services in United Arab Emirates, Saudi Arabia, Qatar and Kuwait with projects executed in Iraq, Oman and Egypt as well. Joint ventures include Olayan Descon in Saudi Arabia, and Presson Descon International Limited (PDIL).
To provide the standard services operations have requisite ISO, OHSAS and ASME certifications in addition to Descon's own QA/QC and HSE standards.
The company is driven by clearly defined vision and strives to add value to its clients businesses by providing world-class solutions at cost-effective levels.
“To become a world-class engineering, manufacturing and construction company operating internationally”.
Descon Manufacturing Works, Lahore (LMW)
Descon Engineering Limited, Karachi
Descon Engineering Abu Dhabi
Descon Engineering FZE, Hamriyah Free Zone, Sharjah
Olayan Descon Engineering Company, Al Jubail, Saudi Arabia
Descon Engineering Qatar LLC, Doha
Descon Engineering, Kuwait
Gas Processing and Compression
Refining Power a. Thermal b. Hydel c. Wind Chemicals a. Hydrogen Peroxide
b. Soda Ash c. Industrial Chemicals Petrochemicals a. Polyester b. PTA c. Ethylene/Polyethylene d. Polypropylene/PDH e. PVC Fertilizer a. Ammonia b. Urea c. DAP Cement Infrastructure a. Dams b. Barrages c. Irrigation Channels d. Motorways e. Buildings Water Treatment a. Public Health b. Industrial c. Waste Water d. Demineralization e. Reverse Osmosis f. Desalination Major Projects:
- Oil & Gas - Power - Fertilizer
- Chemical/ Petrochemical - Cement
- Water & Desalination - Heavy Lifts
Departments of DESCON
Following are the departments of DESCON
- Human Resource Department (HRD) - Marketing and Proposals
- Administration and Finance - Product engineering/Design - Project management
- Procurement - Production
- Manufactured products
- QC & QHSE (Quality health safety environment)
In layout shop according to the drawing we perform two steps
Marking or layout is the process of transferring a design or pattern to a workpiece, as the first step in the manufacturing process.
The following tools which we are in DESCON Layout shop
Measuring tape (meter tape)
Center punch & hammer
Letter punch & number punch Cutting:
For cutting purpose we use following three machines in DESCON
1. Shear cutting machine 2. Gas cutting machine
a) Automatic portable cutting machine b) Profile (copy) cutting machine 3. Plasma cutting machine
1) Shear cutting machine:
Shear cutting machine is used for regular or rectangular parts cutting. It works by first clamping the material with a ram. A moving blade then comes down across a fixed blade to shear the material. For larger shears the moving blade may be set on an angle or
"rocked" in order to shear the material progressively from one side to the other; this angle is referred to as the shear angle. This decreases the amount of force required, but
increases the stroke. A 5 degree shear angle decreases the force by about 20%. The amount of energy used is still the same.
2) Gas cutting machines:
There are two types of gas cutting machines which we are used in DESCON
a. Automatic portable cutting machine:
Automatic portable cutting machine is also called pug machine. This machine is designed for clean, smooth and accurate cutting of mild steel and low alloy carbon steel. It is best suited for straight line, bevel and circular cutting. Machine is well-balanced and does not require counter balancing. The cutting speed can be set instantly and accurately by an indexed selector knob.
b. Profile (copy) cutting machine:
These machines are primarily meant for cutting different shapes such as stars, hexagons, squares, rectangles, circles, triangles, etc. It can also cut straight lines and Bevels up to 45o.
The motor driven Electro Magnetic Tracing Head on the carriage arm traces the profile on the template. This enables the torch to duplicate any intricate shape provided on the template of the machine.
The machines are designed with Pantograph type arms providing a direct line guiding system
A simple and accurate magnetic tracing system helps in maintaining repeatability of the flame cut parts
Precise Ball and Needle bearing design of hinges ensure free and frictionless tracing, enabling greater cutting accuracy
The speed of the machine can be varied with an indexed selector knob. The tracing head can be moved in Clockwise or Anticlockwise direction by a selector switch.
3) Plasma cutting machine:
Plasma cutting is a process that is used to cut steel and other metals of different thicknesses (or sometimes other materials) using a plasma torch. In this process, an inert gas (in some units, compressed air) is blown at high speed out of a nozzle; at the same time an electrical arc is formed through that gas from the nozzle to the surface being cut, turning some of that gas to plasma. The plasma is sufficiently hot to melt the metal being cut and moves sufficiently fast to blow molten metal away from the cut.
There are following machines are uses at DESCON Machine shop, Fabrication shops and Heat exchanger shop.
Drill machine (Radial, Column, Hand) Horizontal and vertical boring machines Horizontal and vertical lathe machines Horizontal and vertical Milling machines CNC milling + drilling machine
Tube bending machine
Tube expending and cutting machine Plate rolling machine
Power saw (Cutting machine)
Grinding machines (Universal, Surface, Cylindrical)
Different Mechanical press machines (bending, punching, cutting, sharing and hole etc)
Share making machine
Drill machine (Radial, Column, Hand):
A Radial Drilling machine is a large gear headed drill press in which the head moves along the arm that radiates from the column of the machine. The arm of the machine can swing in relation to the base of the machine. This swing operation helps the drill head to move out of the way so a large crane can place the heavy work piece on the base of the radial drilling machine. Also this helps in drilling holes at different locations of the work piece without actually moving the work piece.
Horizontal and vertical boring machines:
Boring is the process of enlarging a hole that has already been drilled (or cast), by means of a single-point cutting tool (or of a boring head containing several such tools), for example as in boring a cannon barrel. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole.
The boring process can be executed on various machine tools, including (1) general-purpose or universal machines, such as lathes (/turning centers) or milling machines (machining centers), and (2) machines designed to specialize in boring as a primary function, such as jig borers and boring machines or boring mills.
Horizontal boring machines Vertical boring machines
Horizontal and vertical lathe machines:
The lathe is a machine tool which holds the work piece between two rigid and strong supports called centers or in a chuck or face plate which revolves. The cutting tool is rigidly held and supported in a tool post which is fed against the revolving work. The normal cutting operations are performed with the cutting tool fed either parallel or at right angles to the axis of the work. The cutting tool may also be fed at an angle relative to the axis of work for machining tapers and angles.
Horizontal lathe machines Vertical lathe machines
Horizontal and vertical Milling machines:
A milling machine is a machine tool used to machine solid materials. Milling machines are often classed in two basic forms, horizontal and vertical. (1) A horizontal mill has the same sort of x–y table, but the cutters are mounted on a horizontal arbor (see Arbor milling) across the table. Many horizontal mills also feature a built-in rotary table that allows milling at various angles; this feature is called a universal table.
(2) In the vertical mill the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis.
Horizontal milling machine Vertical milling machine
CNC milling + drilling machine:
CNC milling machines (also called machining centers) are computer controlled vertical mills with the ability to move the spindle vertically along the Z-axis. This extra degree of freedom permits their use in die sinking, engraving applications, and 2.5D surfaces such as relief sculptures. When combined with the use of conical tools or a ball nose cutter, it also significantly improves milling precision without impacting speed, providing a cost-efficient alternative to most flat-surface hand-engraving work.
Tube bending machine:
Tube bending is the umbrella term for metal forming processes used to permanently form pipes or tubing. One has to differentiate between form-bound and freeform-bending procedures, as well as between heat supported and cold forming procedures.
Plate rolling machine:
This machine is used for rolling the plates at different diameters and bending the plates at different angles.
The shaper is a machine tool used primarily for
Producing a flat or plane surface which may be in a horizontal, a vertical or an angular plane.
Making slots, grooves and keyways.
Producing contour of concave/convex or a combination of these.
Grinding machines (Universal, Surface, Cylindrical):
A grinding machine, often shortened to grinder, is a machine tool used for grinding, which is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation. Grinding machines remove material from the workpiece by abrasion, which can generate substantial amounts of heat; they therefore incorporate a coolant to cool the workpiece so that it does not overheat and go outside its tolerance.
Different Mechanical presses:
Mechanical presses are used in industry for different process. There are various types of operations blanking and piercing: lancing, perforating, notching, nibbling, shaving, cutoff, and dinking we perform on mechanical presses.
A boiler is an enclosed vessel that provides a means for combustion heat to be transferred to water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. Water is a useful and inexpensive medium for transferring heat to a process.
Main parts and accessories of Boiler:
Following are the main parts and accessories of boiler
Boiler feed water pump
Chemical Dosing pump
Boiler bundle a. Economizer b. Evaporator c. Super heater
Feed Water preheater
Blow down tank
Oil heating unit, Oil pump
Boiler feed water pump
A boiler feed water pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are normally high pressure units that take suction from a condensate return system and can be of the centrifugal pump type or positive displacement type.
A deaerator is a device that is widely used for the removal of air and other dissolved gases from the feedwater to steam-generating boilers. In particular, dissolved oxygen in boiler feed waters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides (rust). Water also combines with any dissolved carbon dioxide to form carbonic acid that causes further corrosion.
Boiler bundle contains following parts
Economizer is a heat exchanger through which the feedwater is pumped. The feedwater thus arrives in the boiler at a higher temperature than would be the case if no economizer was fitted. Less energy is then required to raise the steam. Alternatively, if the same quantity of energy is supplied, then more steam is raised. This results in a higher efficiency. In broad terms a 10°C increase in feedwater temperature will give an efficiency improvement of 2%.
An evaporator is a device used to turn (or allow to turn) the liquid form of some chemical into its gaseous form. For example, an evaporator is used in an air conditioning system to allow the compressed cooling chemical (for example, Freon) to evaporate from liquid to gas, absorbing heat in the process.
c. Super heater
A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired. A superheater can vary in size from a few tens of feet to several hundred feet (a few meters or some hundred meters).
Boiler designs can be classified in following main divisions:
1. Fire-tube boilers 2. Water-tube boilers 3. Skid mounted boilers
1. Fire tube boiler:
In a fire tube boiler, hot gases pass through the tubes and boiler feed water in the shell side is converted into steam. Fire tube boilers are generally used for relatively small steam capacities and low to medium steam pressures. As a guideline, fire tube boilers are competitive for steam rates up to 12,000 kg/hour and pressures up to 18 kg/cm2. Fire tube boilers are available for operation with oil, gas or solid fuels.
2. Water tube boiler:
In a water tube boiler, boiler feed water flows through the tubes and enters the boiler drum. The circulated water is heated by the combustion gases and converted into steam at the vapor space in the drum. These boilers are selected when the steam demand as well as steam pressure requirements are high as in the case of process cum power boiler / power boilers.
Most modern water boiler tube designs are within the capacity range 4,500 – 120,000 kg/hour of steam, at very high pressures. Many water tube boilers are of “packaged” construction if oil and /or gas are to be used as fuel. Solid fuel fired water tube designs are available but packaged designs are less common.
The features of water tube boilers are:
Forced, induced and balanced draft provisions help to improve combustion efficiency.
Less tolerance for water quality calls for water treatment plant.
Higher thermal efficiency levels are possible.
Boiler fittings and accessories
Water level indicators
Bottom blow down valves
Continuous blow down valve
Automatic Blow down/Continuous Heat Recovery System
Steam drum internals
Low- water cutoff
Surface blow down line
Feed water check valve or clack valve
De super heater tubes or bundles
A pressure vessel is a closed container designed to hold gases or liquids at a pressure substantially different from the ambient pressure.
The pressure differential is dangerous and many fatal accidents have occurred in the history of their development and operation. Consequently, their design, manufacture, and operation are regulated by engineering authorities backed by legislation. For these reasons, the definition of a pressure vessel varies from country to country, but involves parameters such as maximum safe operating pressure and temperature.
There are two types of pressure vessel:
1. Spherical pressure vessel 2. Cylindrical pressure vessel.
Application of pressure vessel:
There are the following main applications of pressure vessels
- Cosmetic industry - Chemical industry
- Food and beverage industry - Oil and fire industry
- Paper and pulp industry
- Pharmaceutical and plastic processing - Power generation
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact. They are widely used in space heating, refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment. The classic example of a heat exchanger is found in an internal combustion engine in which a circulating fluid known as engine coolant flows through radiator coils and air flows past the coils, which cools the coolant and heats the incoming air.
In Parallel flow heat exchanger fluid flowing through a pipe and exchanges heat with another fluid through an annulus surrounding the pipe. In a parallel flows heat exchanger fluids flow in the same direction.
In counter flow heat exchanger fluid flowing through a pipe and exchanges heat with another fluid through an annulus surrounding the pipe. In counter flows heat exchanger fluids flow in the opposite direction.
In a cross-flow heat exchanger the direction of fluids are perpendicular to each other.
Counter flow heat exchangers are most efficient because they allow the highest log mean temperature difference between the hot and cold streams.
Types of Heat Exchangers:
Following heat exchangers are making in DESCON Heat Exchanger shop.
Shell and tube heat exchanger a. U-tube heat exchanger b. Straight tube heat exchanger
Shell and tube heat exchanger:
A Shell and Tube is the most common type of heat exchanger used in the process,
petroleum, chemical and HVAC industries, it contains a number of parallel U-tubes inside a shell. Shell Tube heat exchangers are used when a process requires large amounts of fluid to be heated or cooled. Due to their design, shell tube heat exchangers offer a large heat transfer area and provide high heat transfer efficiency.
Heat exchanger U-tubes are Manufactured in carbon steel grade SA 192 or alloy steel or in stainless steel material.
Shell and tube heat exchanger design:
There can be many variations on the shell and tube design. Typically, the ends of each tube are connected to plenums (sometimes called water boxes) through holes in tube sheets. The tubes may be straight or bent in the shape of a U, called U-tubes.
In nuclear power plants called pressurized water reactors; large heat exchangers called steam generators are two-phase, shell-and-tube heat exchangers which typically have U-tubes. They are used to boil water recycled from a surface condenser into steam to drive a turbine to produce power. Most shell-and-tube heat exchangers are 1, 2, or 4 pass designs on the tube side. This refers to the number of times the fluid in the tubes passes through the fluid in the shell. In a single pass heat exchanger, the fluid goes in one end of each tube and out the other.
Surface condensers in power plants are often 1-pass straight-tube heat exchangers (see Surface condenser for diagram). Two and four pass designs are common because the fluid can enter and exit on the same side. This makes construction much simpler.
There are often baffles directing flow through the shell side so the fluid does not take a short cut through the shell side leaving ineffective low flow volumes.
Heat exchangers are found in most chemical, electrical or mechanical systems. They serve as the system's means of gaining or rejecting heat. Some of the more common applications are found in heating, electronic equipment, ventilation and air conditioning (HVAC) systems, radiators on internal combustion engines, boilers, condensers, and as pre heaters or coolers in fluid systems.
Heat recovery steam generator (HRSG)
A heat recovery steam generator or HRSG is an energy recovery heat exchanger that recovers heat from a hot gas stream. It produces steam that can be used in a process or used to drive a steam turbine.
Heat recovery can be used extensively in energy projects.
In the energy-rich Persian Gulf region, the steam from the HRSG is used for desalination plants.
Universities are ideal candidates for HRSG applications. They can use a gas turbine to produce high reliability electricity for campus use. The HRSG can recover the heat from the gas turbine to produce steam/hot water for district heating or cooling.
Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid.
Types of piping:
There are following two type of piping which is used in LMW DESCON.
Material of pipes:
Industrial process piping can be manufactured by
steel fiberglass glass aluminum plastic copper concrete
Welding is a process of joining two or more metal pieces as a result of significant diffusion of the atoms of the welded pieces into the joint (weld) region. Welding is carried out by heating the joined pieces to melting point and fusing them together (with or without filler material) or by applying pressure to the pieces in cold or heated state.
Advantages of welding:
Strong and tight joining
Simplicity of welded structures design
Welding processes may be mechanized and automated
Disadvantages of welding:
Internal stresses, distortions and changes of micro-structure in the weld region
Harmful effects: light, ultra violate radiation, fumes, high temperature
Applications of welding:
Buildings and bridges structures
Automotive, ship and aircraft constructions
Tanks and vessels
Machinery elements Welding processes:
Following methods are used in Welding section DESCON.
1. Shielded Metal Arc Welding (SMAW) 2. Submerged Arc Welding (SAW)
3. Gas Metal Arc Welding (GMAW, MIG) a. MIG
4. Gas Tungsten Arc Welding (GTAW, TIG) 5. Flux Cored Arc Welding (FCAW)
1. Shielded Metal Arc Welding (SMAW)
Shielded metal arc welding (Stick welding, Manual metal arc welding) uses a metallic consumable electrode of a proper composition for generating arc between itself and the parent work piece. The molten electrode metal fills the weld gap and joins the work pieces. This is the most popular welding process capable to produce a great variety of welds.
The electrodes are coated with a shielding flux of a suitable composition. The flux melts together with the electrode metallic core, forming a gas and a slag, shielding the arc and the weld pool. The flux cleans the metal surface, supplies some alloying elements to the weld, protects the molten metal from oxidation and stabilizes the arc. The slag is removed after Solidification.
Advantages of Shielded Metal Arc Welding (SMAW):
Simple, portable and inexpensive equipment;
Wide variety of metals, welding positions and electrodes are applicable;
Suitable for outdoor applications.
Disadvantages of Shielded Metal Arc Welding (SMAW):
The process is discontinuous due to limited length of the electrodes;
Weld may contain slag inclusions;
2. Submerged Arc Welding (SAW)
Submerged Arc Welding is a welding process, which utilizes a bare consumable metallic electrode producing an arc between itself and the work piece within a granular shielding flux applied around the weld.
The arc heats and melts both the work pieces edges and the electrode wire. The molten electrode material is supplied to the surfaces of the welded pieces, fills the weld pool and joins the work pieces.
Since the electrode is submerged into the flux, the arc is invisible. The flux is partially melts and forms a slag protecting the weld pool from oxidation and other atmospheric contaminations.
Advantages of Submerged Arc Welding (SAW):
Very high welding rate
The process is suitable for automation
High quality welds structure
Disadvantages of Submerged Arc Welding (SAW):
Weld may contain slag inclusions
3. Gas Metal Arc Welding (GMAW, MIG)
Gas Metal Arc Welding or Metal Inert Gas Welding (GMAW, MIG) is an arc welding process, in which the weld is shielded by an external gas (Argon, helium, CO2, argon + Oxygen or other gas mixtures).
Consumable electrode wire, having chemical composition similar to that of the parent material, is continuously fed from a spool to the arc zone. The arc heats and melts both the work pieces edges and the electrode wire. The fused electrode material is supplied to the surfaces of the work pieces, fills the weld pool and forms joint.
Due to automatic feeding of the filling wire (electrode) the process is referred to as a semi-automatic. The operator controls only the torch positioning and speed.
Advantages of Metal Inert Gas Welding (MIG, GMAW):
Continuous weld may be produced (no interruptions)
High level of operators skill is not required
Slag removal is not required (no slag);
Disadvantages of Metal Inert Gas Welding (MIG, GMAW):
Expensive and non-portable equipment is required;
Outdoor applications are limited because of effect of wind, dispersing the shielding gas.
4. Gas Tungsten Arc Welding (GTAW, TIG)
Gas Tungsten Arc Welding or Tungsten Inert Gas Arc Welding (GTAW, TIG) is a welding process, in which heat is generated by an electric arc struck between a tungsten non-consumable electrode and the work piece. The weld pool is shielded by an inert gas (Argon, helium, Nitrogen) protecting the molten metal from atmospheric contamination.
The heat produced by the arc melts the work pieces edges and joins them. Filler rod may be used, if required. Tungsten Inert Gas Arc Welding produces a high quality weld of most of metals. Flux is not used in the process.
Advantages of Tungsten Inert Gas Arc Welding (TIG, GTAW)
Weld composition is close to that of the parent metal;
High quality weld structure
Slag removal is not required (no slag);
Thermal distortions of work pieces are minimal due to concentration of heat in small zone.
Disadvantages of Tungsten Inert Gas Arc Welding (TIG, GTAW):
Low welding rate;
5. Flux Cored Arc Welding (FCAW)
Flux cored arc welding (FCAW) is an electric arc welding process which fuses together the parts to be welding by heating them with an arc between a continuously fed flux filled electrode wire and the work. Shielding is obtained through decomposition of the flux within the tubular wire (self shielded method). Additionally shielding may be obtained from an externally supplied gas or gas mixture (gas shielded method). Equipment is similar to that used for Gas Metal Arc welding (GMAW).
Welding is normally limited to the flat and horizontal positions with large diameter wires. Smaller diameter wires are used in all positions. A layer of slag is left on the weld bead that must be removed after welding.
Advantages of FCAW
Deposition rate is high with larger diameter wires, and for positional welding.
Deeper penetration is possible than with GMAW.
FCAW has high operator appeal: process is easy to use and welds are of good appearance.
Good quality welds and appearance.
Wide range of steel types over a range of thickness.
Disadvantages of FCAW
High capital cost of machinery, maintenance required on wire feed system.
Accessibility to the welding joint is restrictive because of the size of the gun.
The available length of the welding lead can be restrictive.
Electrode is more expensive ($/kg) than GMAW.
Produces more smoke and fumes than GMAW.
Slag covering needs to be removed.
There are four basic welding positions, or orientations, that have been defined by the American Welding Society. They are
1. Flat 1G / 1F
2. Horizontal 2G / 2F
3. Vertical 3G / 3F
4. Overhead 4G / 4F
5. 5G & 6G is used for pipe welding 5G& 6G
These positions are designated by the number that relates to the position followed by a letter that designates the type of weld; (F) for fillet weld, and (G) for groove weld.
The weld joint is where two or more metal parts are joined by welding. The five basic types of weld joints are the butt, corner, tee, lap, and edge, as shown in figure.
A butt joint is used to join two members aligned in the same plane. This joint is frequently used in plate, sheet metal, and pipe work. A joint of this type may be either square or grooved.
Corner and tee joints are used to join two members located at right angles to each other. In cross section, the corner joint forms an L-shape, and the tee joint has the shape of the letter T.
A lap joint, as the name implies, is made by lapping one piece of metal over another. This is one of the strongest types of joints.
An edge joint is used to join the edges of two or more members lying in the same plane.
Welding symbols, like sign posts are informational directors. They are placed on drawings by Welding engineers and their purpose is to relay information to the weld operator. In many instances the information relayed is very simple.
Occasionally it is necessary for the engineer to relay complicated information. Therefore it is important that weld operators understand the symbols and are capable of interpreting the needs of the engineer.
For the most part weld symbols are standard throughout the world, although there are symbols that are devised and used only by the company that devised them.
When we put the above elements together we see the result in fig. 007. The finished symbol instructs the weld operator to deposit a 1/4” fillet weld both sides of the joint and that the preferred welding rod will be a E7018.
The symbol shown in following fig. indicates that the vertical component requires beveling prior to assembly. The remainder of the symbol indicates that a 1/4” fillet is required to complete the weld. This symbol would usually be accompanied with
additional notes and instruction. The additional notes would probably reference a specific weld procedure, which would indicate the number and sequence of multiple passes required to complete the finished weld.
The following illustrations show simple weld symbols and the resulting application.
Sandblasting is used to clean surfaces, remove rust, oxidation, or finishes, preparing surfaces for new coating applications. It is highly effective for large equipment, surface prepping and paint/rust removal. The pressure of is 120 psi or 7.5 bar used. Sandblasting is mostly used for Stainless steel and Mild Steel members.
Sand Blasting Equipments:
Hopper (Sand blasting machine)
Blasting pipe ( )
Adopter for nozzle
Nozzle (4mm to 9mm dia)
Dead man switch for safety
Sand Blasting Materials:
Following materials are used,
Steel shorts Aluminum oxide Glass beads Steel grit Garnet Silica sand Larnuspur sand
Galvanizing is the process of applying a zinc coating to fabricated iron or steel material by immersing the material in a bath consisting primarily of molten zinc. The simplicity of the galvanizing process is a distinct advantage over other methods of providing corrosion protection. The automotive industry depends heavily on this process for the production of many components used in car manufacturing. Galvanizing forms a metallurgical bond between the zinc and the underlying steel or iron, creating a barrier that is part of the metal itself.
1. First of all dip the steel or iron material in caustic soda which is the cause of oil removing.
2. Then dip in fresh water which is called rinsing.
3. Then dip in HCL bath for 20 to 30 minutes which is the cause of rust removing. 4. Then dip in fresh water which is called rinsing.
5. Then dip in the flux bath (Ammonium chloride + Zinc chloride) for 2 to 3 minutes which is the cause of coating of flux.
6. Then put on heater for some time for drying the material.
7. Then dip in Zinc bath which has 4500C temperature for 4 to 5 minutes for the coating of zinc.
8. Then dip in fresh water for quenching the material.
Stress Relieving Furnace
Stress Relieving Furnace also called post welding heat treatment (PWHT) is used for relieving the stress from parts after machining and welding. This is used for C.S (Carbon steel) and Alloy parts. Machining and Welding induces stresses in parts. These stresses can cause distortions in the part long term. If the parts are clamped in service, then cracking could occur. Also hole locations can change causing them to go out of tolerance. For these reasons, stress relieving is often necessary.
Stress relieving is done by subjecting the parts to a temperature of about 75 ºC (165 ºF) below the transformation temperature, line A1 on the diagram, which is about 727 ºC (1340 ºF) of steel thus stress relieving is done at about 650 ºC (1202 ºF) for about one hour or till the whole part reaches the temperature. This removes more than 90% of the internal stresses. Alloy steels are stress relieved at higher temperatures. After removing from the furnace, the parts are air cooled in still air.
Main parts of Stress Relieving Furnace: Bed of furnace Furnace Burners Thermocouples Main stack Control panel
Capacity of the furnace:
Length of the furnace = 20 meter
Width of the furnace = 4.5 meter
Height of the furnace = 4.5 meter
Maximum bed load = 300 Ton
Max temperature of the furnace = 750o C
Non Destructive Test (NDT)
Nondestructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. The terms Nondestructive examination (NDE), Nondestructive inspection (NDI), and Nondestructive evaluation (NDE) are also commonly used to describe this technology. Because NDT does not permanently alter the article being inspected, it is a highly-valuable technique that can save both money and time in product evaluation.
Following methods are used in NDT DESCON.
a) Radiographic test (RT) b) Ultrasonic test (UT)
c) Penetrant test (PT) or Die penetrant test (DPT) d) Magnetic test (MT) or Magnetic particle test (MPT)
a) Radiographic test (RT)
Radiographic Testing (RT), or industrial radiography, is a nondestructive testing (NDT) method of inspecting materials for hidden flaws by using the ability of short wavelength electromagnetic radiation (high energy photons) to penetrate various materials.
Either an X-ray machine or a radioactive source (Ir-192, Co-60, or in rare cases Cs-137) can be used as a source of photons. Neutron radiographic testing (NR) is a variant of radiographic testing which uses neutrons instead of photons to penetrate materials. This can see very different things from X-rays, because neutrons can pass with ease through lead and steel but are stopped by plastics, water and oils.
X-rays are used to produce images of objects using film or other detector that is sensitive to radiation. The test object is placed between the radiation source and detector. The thickness
and the density of the material that X-rays must penetrate affect the amount of radiation reaching the detector. This variation in radiation produces an image on the detector that often shows internal features of the test object.
Used for the inspection of almost any material for surface and subsurface defects. X-rays can also be used to locates and measures internal features, confirm the location of hidden parts in an assembly, and to measure thickness of materials.
Can be used to inspect virtually all materials.
Detects surface and subsurface defects.
Ability to inspect complex shapes and multi-layered structures without disassembly.
Minimum part preparation is required.
Extensive operator training and skill required.
Access to both sides of the structure is usually required.
Orientation of the radiation beam to non-volumetric defects is critical.
Field inspection of thick section can be time consuming.
Relatively expensive equipment investment is required.
Possible radiation hazard for personnel.
b) Ultrasonic Test (UT)
In ultrasonic testing (UT), very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to characterize materials. The technique is also commonly used to determine the thickness of the test object, for example, to monitor pipe work corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution. It is a form of non-destructive testing used in many industries including aerospace, automotive and other transportation sectors.
High frequency sound waves are sent into a material by use of a transducer. The sound waves travel through the material and are received by the same transducer or a second transducer. The amount of energy transmitted or received and the time the energy is received are analyzed to determine the presence of flaws. Changes in material thickness and changes in material properties can also be measured. The machine displays these results in the form of a signal with amplitude representing the intensity of the reflection and the distance, representing the arrival time of the reflection.
Used for the location of surface and subsurface defects in many materials including metals, plastics, and wood. Ultrasonic inspection is also used to measure the thickness of materials and otherwise characterize properties of material based on sound velocity and attenuation measurements.
High penetrating power, which allows the detection of flaws deep in the part.
High sensitivity, permitting the detection of extremely small flaws.
Only one surface need be accessible.
Greater accuracy than other nondestructive methods in determining the depth of internal flaws and the thickness of parts with parallel surfaces.
Some capability of estimating the size, orientation, shape and nature of defects.
Nonhazardous to operations or to nearby personnel and has no effect on equipment and materials in the vicinity.
Manual operation requires careful attention by experienced technicians
Extensive technical knowledge is required for the development of inspection procedures.
Parts that is rough, irregular in shape, very small or thin, or not homogeneous are difficult to inspect.
Surface must be prepared by cleaning and removing loose scale, paint, etc., although paint that is properly bonded to a surface need not be removed.
Couplants are needed to provide effective transfer of ultrasonic wave energy between transducers and parts being inspected unless a non-contact technique is used. Non-contact techniques include Laser and Electro Magnetic Acoustic Transducers (EMAT).
Inspected items must be water resistant, when using water based couplants that do not contain rust inhibitors.
c) Penetrant test (PT) or Die penetrant test (DPT)
Dye penetrant inspection (DPI), also called liquid penetrant inspection (LPI) or penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface breaking defects in all non porous materials (metals, plastics, or ceramics). The penetrant may be applied to all non ferrous materials and ferrous materials; although for ferrous components magnetic-particle inspection is often used instead for its subsurface detection capability. LPI is used to detect casting, forging and welding surface defects such as hairline cracks, surface porosity, leaks in new products, and fatigue cracks on in-service components.
DPI is based upon capillary action, where surface tension fluid low penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed, a developer is applied. The developer helps to draw penetrant out of the flaw where a visible indication becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending upon the type of dye used - fluorescent or no fluorescent (visible).
a) Cleaning the surface (1)
b) Adding the first chemical liquid (penetrant) (3) where it goes through to the crack (2) c) Cleaning the surface once more. Though, some of the first chemical remains inside of
d) Adding the second chemical liquid (developer) (4), where the first liquid (5) penetrate to the second, so that the area of the crack will be shown to our eyes in a bigger scale
Used to locate cracks, porosity, and other defects that break the surface of a material and have enough volume to trap and hold the penetrant material. Liquid penetrant testing is used to inspect large areas very efficiently and will work on most nonporous materials.
Large surface areas or large volumes of parts/materials can be inspected rapidly and at low cost.
Parts with complex geometry are routinely inspected.
Indications are produced directly on surface of the part providing a visual image of the discontinuity.
Equipment investment is minimal.
Detects only surface breaking defects.
Surface preparation is critical as contaminants can mask defects.
Requires a relatively smooth and nonporous surface.
Post cleaning is necessary to remove chemicals.
Requires multiple operations under controlled conditions.
d) Magnetic test (MT) or Magnetic particle test (MPT)
Magnetic particle inspection (MPI) is a non-destructive testing (NDT) process for detecting surface and subsurface discontinuities in ferroelectric materials such as iron, nickel, cobalt, and some of their alloys. The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. Direct magnetization occurs when the electric current is passed through the test object and a magnetic field is formed in the material. Indirect magnetization occurs when no electric current is passed through the test object, but a magnetic field is applied from an outside source. The magnetic lines of force are perpendicular to the direction of the electric current which may be either alternating current (AC) or some form of direct current (DC) (rectified AC).
A magnetic field is established in a component made from ferromagnetic material. The magnetic lines of force travel through the material and exit and reenter the material at the poles. Defects such as crack or voids cannot support as much flux, and force some of the flux outside of the part. Magnetic particles distributed over the component will be attracted to areas of flux leakage and produce a visible indication.
Used for the inspection of ferromagnetic materials (those that can be magnetized) for defects that result in a transition in the magnetic permeability of a material. Magnetic particle inspection can detect surface and near surface defects.
Large surface areas of complex parts can be inspected rapidly.
Can detect surface and subsurface flaws.
Surface preparation is less critical than it is in penetrant inspection.
Magnetic particle indications are produced directly on the surface of the part and form an image of the discontinuity.
Equipment costs are relatively low.
Only ferromagnetic materials can be inspected.
Large currents are needed for very large parts.
Requires relatively smooth surface.
Paint or other nonmagnetic coverings adversely affect sensitivity.
Demagnetization and post cleaning is usually necessary.
Applications of Non Destructive Testing
NDT is used in a variety of settings that covers a wide range of industrial activity.
Automotive o Engine parts o Frame Aviation / Aerospace o Airframes Space frames o Power plants Propellers Reciprocating Engines
Gas turbine engines
Maintenance, repair and operations
o Machine parts
o Castings and Forgings
Industrial plants such as Nuclear, Petrochemical, Power, Refineries, Pulp and Paper, Fabrication shops, Mine processing and their Risk Based Inspection programmes.
o Pressure vessels o Storage tanks o Welds o Boilers o Heat exchangers o Turbine bores o In-plant Piping Miscellaneous o Pipelines
In-line Inspection using "pigs"
Pipeline integrity management
o Tubular NDT, for Tubing material
o Corrosion Under Insulation (CUI)
o Amusement park rides
o Submarines and other Naval warships
Quality Assurance & Quality control (QA & QC):
Quality control is the more traditional way that businesses have used to manage qualit y. Quality control is concerned with checking and reviewing work that has been done.
Under traditional quality control, inspection of products and services (checking to make sure that what's being produced is meeting the required standard) takes place during and at the end of the operations process.
There are three main points during the production process when inspection is performed:
1. When raw materials are received prior to entering production, 2. Whilst products are going through the production process,
3. When products are finished - inspection or testing takes place before products are dispatched to customers.
The problem with this sort of inspection is that it doesn't work very well!
There are several problems with inspection under traditional quality control:
The inspection process does not add any "value". If there were any guarantees that no defective output would be produced, then there would be no need for an inspection process in the first place!
Inspection is costly, in terms of both tangible and intangible costs. For example, materials, labour, time, employee morale, customer goodwill, lost sales.
It is sometimes done too late in the production process. This often results in defective or non-acceptable goods actually being received by the customer
It is usually done by the wrong people - e.g. by a separate "quality control inspection team" rather than by the workers themselves
Inspection is often not compatible with more modern production techniques (e.g. "Just in Time Manufacturing") which do not allow time for much (if any) inspection.
Working capital is tied up in stocks which cannot be sold.
There is often disagreement as to what constitutes a "quality product". For example, to meet quotas, inspectors may approve goods that don't meet 100% conformance, giving the message to workers that it doesn't matter if their work is a bit sloppy. Or one quality control inspector may follow different procedures from another, or use different measurements.
As a result of the above problems, many businesses have focused their efforts on improving quality by implementing quality management techniques - which emphasize the role of quality assurance. As Deming (a "quality guru") wrote:
"Inspection with the aim of finding the bad ones and throwing them out is too late, ineffective, and costly. Quality comes not from inspection but from improvement of the process."
QA & QC DESCON LMW:
Relation of Production and Quality Control (QC) in DESCON LMW.
Production Quality control (QC)
1. Material (Store) Incoming QC Inspector 2. Layout (Supervisor production) QC Inspector material 3. Fabrication shop (Foreman) QC fabrication Inspector
(Fitups, Rolling, Bending, machining activities)
4. Welding (Welding Engineer) a. Welding documents (WPS, Weld matrix) b. Welder qualification
5. PWHT PWHT specifications
(Post Welding Heat Treatment) (a) Service b) Code c) Fabrication procedure
6. Final Inspection (Production) QC Inspector
7. Hydraulics or pneumatic test Hydraulics test report 8. Blasting / Galvanizing (Surface preparation) -
9. Dispatch -
Third party inspection:
ASME testing authority, HSB is a local testing company which has reduced cost of hiring a foreign expert.
Codes & Standards
The following standards are used in DESCON LMW.
German & European:
TRD (Technical Rules Directives)
EN (European Standards)
BS (British Standards)
NBIC (National Board Inspection Code)
AD Markblatter (for pressure vessels)
ASME (American society of mechanical engineering):
The following code sections are used in DESCON LMW for Boilers and Pressure vessels
SEC I Rules for constructions of Power Boilers
SEC II Materials
SEC V Nondestructive Examinations
SEC VIII Rules for constructions of pressure vessels - Division 1
- Division 2
SEC IX Welding and Brazing Qualifications
DESCON LMW has the following standard stamps
A for Assembly
S for Boilers Section I
U for Pressure vessels Section VIII Division 1
U 2 for Pressure vessels Section VIII Division 1
PP for power piping
R for Repair jobs
Roles / Functioning
-To catch the clients
-To prepare the presentations Proposal Engineer
- To prepare the budget for specific job Project Leader
-Simplest or preliminary drawing from BD
- Team leader - Prepare BOQ - Indent material
- To liaison with client for different matters - Follow up
- Expedite the job
- To distribute the project specifications - To prepare the progress sheet
- To plan the job
- To prepare the detail budget Project Engineer Inputs - plan - Budget - Specifications - Drawings - WM/WPS/PQR - QIP/ITP Outputs
- To prepare 1.4 plan through P3 plan - To prepare the weld map
- To expedite the work
- To plan the man power and machine resources - To liaison with different departments
- To distribute the ITP/QIP/Welding documents and drawings to different subsections of production
- To prepare the memo (allocation of man hours and productivity to different subsections of production department
- To prepare QIP/ITP
- To prepare the Hydro test / PWIT/Pneumatic and other procedures - To arrange the inspector for inspection
- To prepare the standard company procedures formats method statement and standard operating procedures
- He is the person who is directly supervise his work man ship and expedite the job. Inputs - Drawings - Specifications - QIP/ITP - WM/WPS/PQR Outputs - Finished goods
-Tack welder Welding Engineer Inputs
- Weld plans - Specifications - Drawings - Consumable lists Outputs - Welding documents - WM (weld matrix)
- WPS (welding procedure specifications) - PQR (procedure qualification record) Design
- Client date sheet - Client specifications
- Approved drawings - Standard tolerance sheet PMT (Project Management) Inputs - Client specifications - Preliminary drawings Outputs - Material indent - Budget revise - Client coordination Production Inputs - Drawings - Specifications - QIP/ITP - Welding documents Outputs
HSE department exists but it is not Functional properly, so efforts require in improving its efficiency.
In internship program there must exist some assessment procedure to induce quality in the internship.
The induction of Latest technologies like CNC machines usually save time and enhance output, so it should be considered to add more in company’s output.
In order to improve working environment and company’s profit workers facilities are looking for things to add in it.