chinmoy pathak choudhury_iocl internship report
TRANSCRIPT
WINTER INTERNSHIP IN
INDIAN OIL CORPORATION LIMITED, BONGAIGAON REFINERY
SUBMITTED BY CHINMOY PATHAK CHOUDHURY
2nd JAN, 2013 – 17th JAN, 2013
DEPARTMENT OF CIVIL ENGINEERING
ASSAM ENGINEERING COLLEGE, JALUKBARI
GUWAHATI – 781013
Table of Contents
Chapter 1 Occupational safety and health in construction industry 1
1 Hazards and their solutions 2
2 Safety checklists for Personal Protective Equipment (PPE) 6
3 Common violations on-site 7
4 Safety rules 11
5 Overview of statutes applicable to construction industry 13
Chapter 2 Structural welding 14
1 Welding terminology 14
2 Common types of welds 16
3 Welding positions 20
4 Weld symbols 21
Chapter 3 Storage of cement bags in warehouse 23
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
CHAPTER 1: OCCUPATIONAL SAFETY AND HEALTH IN CONSTRUCTION INDUSTRY
Construction Sector is very essential and an integral part of Infrastructure development
which gives tremendous boost to our country’s economy. The construction industry had
registered enormous growth worldwide in recent years. Although the development of
technology is rapid in most of the sectors, construction work is still labour intensive.
In India, the construction sector employs around 33 million people, which is next to
agriculture. The construction workers are one of the most vulnerable segment of the
unorganized labour in our country. Workers being exposed to wide variety of serious hazards,
the rate of fatal accidents in this industry is 4 to 5 times to that of manufacturing. The workers
are also exposed to a host hazardous substances which have a potential to cause serious
occupational diseases such as asbestoisis, silicosis, lead poisoning, etc. There is also a
serious potential of fires dues to the storage and use of flammable substances and a potential
for disasters due to collapse of the structures and the subsidence of the soil on which the
construction activity is being carried out.
There are numerous challenges of Construction Industry in construction activities in
India. Some of them are listed as the following.
1. Transport
2. Infrastructure
3. Migrating Work force
4. Social hazards at site
5. Culture
6. Competent Man power
7. Awareness
8. Unorganized Sector
9. Labour Camps
10. Training Infrastructure
Each year, there are thousands of injuries and triple-digit numbers of fatal accidents
related to machine and equipment operation. A lot of these accidents involve the operator, but
over half involve people on the ground - spotters, co-workers, laborers, shovel hands, passers-
by and sidewalk superintendents who get too close. And because of the forces and physics
involved, these are usually not first-aid injuries; there is often an ambulance called to the
jobsite.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Potential hazards for workers in construction include:
Falls (from heights);
Trench collapse;
Scaffold collapse;
Electric shock and arc flash/arc blast;
Failure to use proper personal protective equipment; and
Repetitive motion injuries.
1. Hazards and their solutions: Some hazards and their solutions are enumerated below.
1.1. Scaffolding: When scaffolds are not erected properly, fall hazards can occur.
Solutions:
Scaffold must be sound, rigid and
sufficient to carry its own weight plus
four more times thr maximum intended
load without settling or displacement. It
must be erected on solid footing.
Unstable objects, such as barrels,
boxes, loose bricks or concrete blocks
must not be used to scaffolds or planks.
Scaffolds must not be erected, moved,
dismantled or altered except under the
supervision of a competent person.
Scaffold accessories such as braces,
brackets, trusses, screw legs or ladders
that are damaged or weakened from
any cause must be immediately repaired
or replaced.
A competent person must inspect the
scaffolding and, at designated intervals,
reinspect it.
Synthetic and natural rope used in
suspension must be protected from
heat-pruducing sources.
Scaffolds must be at least 10 feet from
electric power lines at all times.
Fig 1: A Scaffold
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
1.2. Fall Protection: Each year, falls consistently account for the greatest number of fatalities in
the construction industry. A number of factors are often involved in falls, including unstable
working surfaces, misuse or failure to use fall protection equipment and human error.
Studies have shown that using guardrails, fall arrest-systems, safety nets, covers and
restraint systems can prevent many deaths and injuries from falls.
Solutions:
Use of aerial lifts or elevated platforms
to provide safer elevated working
surfaces.
Erecting guardrail systems with
toeboards and warning lines or
installing control line systems to protect
workers near the edges of floors and
roofs.
Using safety net systems or personal
fall arrest systems (body harnesses).
Fig 2. A worker with fall protection
equipments
1.3. Hazard Communication: Failure to recognize the hazards associated with chemicals can
cause chemical burns, respiratory problems, fires and explosions.
Solutions:
Maintain a Material Safety Data Sheet (MSDS) for each chemical in the facility.
Make this information accessible to employees at all times in a language or formats that
are clearly understood by all affected personnel.
Train employees on how to read and use the MSDS.
Follow manufacturer's MSDS instructions for handling hazardous chemicals.
Train employees about the risks of each hazardous chemical being used.
Provide spill clean-up kits in areas where chemicals are stored.
Have a written spill control plan.
Train employees to clean up spills, protect themselves and properly dispose of used
materials.
Provide proper personal protective equipment and enforce its use.
Store chemicals safely and securely.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
1.4. Stairways: Slips, trips and falls on stairways are a major source of injuries and fatalities
among construction workers.
Solutions:
Stairway treads and walkways must be free from dangerous objects, debris and
materials.
Slippery conditions on stairways and wlakways must be corrected immediately.
One should make sure that the treads cover the entire step and landing.
Standways having four or more risers or rising than 30 inches must have at least one
handrail.
1.5. Ladders: Ladders are another source of injuries and fatalities among construction workers.
Solutions:
Using the correct ladder for the task.
A competent person should inspect a
ladder before use of any defects
such as structural defects; grease or
dirt that could cause slip or fall;
paints or stickers that could hide
possible defects.
It should be ensured that the ladders
are long enough to reach the work
area.
One should mark or tag damaged or
defective ladders for repair or
replacement, or destroy them
immediately after coming into notice
that the same ladder in unsuitable for
use.
Never load ladders beyond the
maximum intended load or beyond
the manufacturer’s rated capacity. Avoid using ladders with metallic
components near electrical work and
overhead power lines.
Fig 3. A worker using a ladder
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
1.6. Trenching: Trench collapses cause dozens of fatalities and hundreds of injuries each year.
Solutions:
One should never enter an unprotected trench.
Employ a registered professional engineer to design a protective system for trenches 20
feet or greater.
Always provide a way to exit the trench wall at an angle inclined away from the
excavation not steeper than a height/depth ratio of 11-2:1, according to the sloping
requirements for the type of soil.
Keep spoils at least two feet back from the edge of the trench.
1.7. Cranes: Significant and serious injuries may occur if cranes are not inspected before use
and if they are not used properly. Often these injuries occur when a worker is struck by an
overhead load or caught within the crane's swing radius. Many crane fatalities occur when
the boom of a crane or its load line contact an overhead power line.
Solutions:
All crane controls should be checked to
ensure proper operation before use.
Inspecting wire rope, chains and hook
for any damage.
Knowing the weight of the load that the
crane is to lift.
Ensuring that the load does not exceed
the crane's rated capacity.
One should not move a load over a
workers.
Barricade accessible areas within the
crane's swing radius.
Watch for overhead electrical
distribution and transmission lines and
maintain a safe working clearance of at
least 10 feet from energized electrical
lines.
Fig 4: A Crane
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
2. Safety Checklists for Personal Protective Equipment (PPE): The Following checklist
helps to take steps to avaoid hazards that causes injuries, illnesses and fatalities.
2.1. Eye and Face Protection:
Safety glasses or face shields prevents foreign objects from getting into the eye such as
during welding, cutting, grindling, nailing.
Eye and face protectors are selected based on anticipated hazards.
Safety glasses and shields are worn when exposed to any electrical hazards including
work on energized electrical systems.
2.2. Foot Protection:
Construction workers should wear safety shoes or boots witgslip-resistant and puncture-
resistant soles.
Safety-toed footwear is worn to prevent crushed toes when working around heavy
equipment or falling objects.
2.3. Hand Protection:
Gloves should fit snugly.
Workers should wear the right gloves for the job (for example, heavy-duty rubber gloves
for concrete work, welding gloves for welding, insulated gloves and sleeves when
exposed to electrical hazards).
2.4. Head Protection:
Workers shall wear hard helmets where there is a potential for objects falling from
above, bumps to their heads from fixed objects, or of accidental head contact with
electrical hazards.
They should also be routinely inspected for dents, cracks or deterioration. They are
maintained in good condition.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
3. Common Violations on-site: The following set of pictures describe some of the most
common violations committed on-site. Such malpractices should be avoided.
Fig 5: Bad Storage – Sagging Rack
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Fig 6: Cement Storage – Loading against wall and upto the ceiling
Fig 7: Badly maintained fire protection
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Fig 8: Gas Cylinders kept horizontally in the open
Fig 9: Unsafe Ladder
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Fig 10: Unsafe Access
Fig 11: Unsafe Act – standing on moving vehicle
Fig 12: Unsafe mechanical material handling equipment
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
4. Safety Rules: Safety awareness and caution when performing the most routine operation
are characteristics of a good operator. The larger or more complex the machine, the more
in-depth the training should be. Some common construction safety rules are summarised
below.
a. Keeping mind on work at all times. Injury or termination or both can be the result due to
such carelessness.
b. Personal safety equipment must be worn as prescribed for each job, such as: safety
glasses for eye protection, hard hats at all times within the confines of the construction
area where there is a potential for falling materials or tools, gloves when handling
materials, and safety shoes are necessary for protection against foot injuries.
c. If any part of the body comes in contact with an acid or caustic substance, the affected
part must be washed immediately in the nearest water available site and medical aid must
be secured.
d. One should watch where he/she is walking.
e. The use of illegal drugs or alcohol or being under the influence of the same on the project
is strictly prohibited.
f. One should not distract the attention of fellow workers and should not engage in any act
which would endanger another employee.
g. To keep the working area free from rubbish and debris.
h. To never move an injured person unless it is absolutely necessary. Further injury may
result. Instead, keep the injured as comfortable as possible and utilize job site first-aid
equipment until an ambulance arrives.
i. To know where fire-fighting equipment is located and be trained on how to use it.
j. Nobody but operator is allowed to ride on equipment.
k. To not use power tools and equipment until one have been properly instructed in the safe
work methods and become authorized to use them.
l. One should be sure that all guards are in place. Do not remove, displace, damage, or
destroy any safety device or safeguard furnished or provided for use on the job, nor
interfere with the use thereof.
m. Do not enter an area which has been barricaded.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
n. If one must work around power shovels, trucks, and dozers, make sure operators can
always see him/her. Barricades are required for cranes.
o. Never oil, lubricate, or fuel equipment while it is running or in motion.
p. Defective ladders must be properly tagged and removed from service.
q. To keep ladder bases free of debris, hoses, wires, materials, etc.
r. Never throw anything "overboard". Someone passing below may be seriously injured.
s. One must securely engage the entire hand and foot to avoid a toe-hold or finger-hold grip.
Use of a step ladder for access when no hand or foot holds are provided and one should
avoid carrying objects while climbing.
t. Using proper tie-down procedures. If using compression chain binders, use caution when
opening the handle. The load may shift just enough to add tension to the chain and the
handle may spring open.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
5. Overview of statutes applicable to construction industry:
Building & other construction Workers (regulation of Employment and Conditions of
Service Act, 1996) (BOCWA)
Building & other Construction Workers (Regulation of Employment and Condition of
Service) Central Rules, 1998 (BOCWR)
Petroleum act, 1934 (PA)
Petroleum Rules, 2002 (PR)
Explosives Act, 1884 (EA)
Explosives Rules, 1983 (ER)
Gas Cylinder Rules, 1981 (GCR)
Static & Mobile Pressure Vessel (Unfired) Rules, 1981 (SMPVR)
Electricity Act, 2003 (EA)
Indian Electricity Rules, 1956 (ER)
Motor Vehicles Act, 1988 (MVA)
Central Motor Vehicles Rules, 1989 (CMVR)
In 1996, the Building and other construction Workers (Regulation of Employment and
Conditions of Service) Act, 1996 was promulgated. The Central Rules under this Act were
notified in November, 1998. The Central Government has notified its Chief Labour
Commissioner as the Central enforcement agency under the above act.
The National Safety Council (national and unit levels) has been conducting training
programmes, safety audits, information dissemination, producing awareness material and
organizing campaigns for the construction industries for over a decade.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
CHAPTER 2: STRUCTURAL WELDING
Welding is a fabrication or sculptural process that joins materials, usually metals or
thermoplastics, by causing coalescence. In other words, welding is the process of fusing
multiple pieces of metal together by heating the filler metal to a liquid state. This is often done
by melting the workpieces and adding a filler material to form a pool of molten material
(the weld pool) that cools to become a strong joint. This is in contrast
with soldering and brazing, which involve melting a lower-melting-point material between the
workpieces to form a bond between them, without melting the workpieces.
Many different energy sources can be used for welding, including a gas flame,
an electric arc, etc. While often an industrial process, welding may be performed in many
different environments, including open air, under water and in outer space. Welding is a
potentially hazardous undertaking and precautions are required to avoid burns, electric shock,
vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet
radiation. A properly welded joint is stronger than the base metal.
Welding is a common method for connecting structural steel. Many fabrication shops
prefer welding rather bolting. There are several welding processes, types, and postions to be
considered in building construction.
1. Welding Terminology:
Fig 13: A Tee Joint
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
a. Actual Throat: It is the minimum distance between the weld root and the weld face.
b. Convexity: It refers to the convex nature of the outer surface of weld.
c. Effective Throat: It is the distance from the root of a weld to the face of the weld, with the
amount of weld reinforcement subtracted.
d. Weld Leg: It is the distance from the root to the toe of the fillet weld. The size of
the fillet weld is determined by the length of its legs.
e. Weld Size: (a) Fillet weld size – For equal fillet welds, the leg lengths of the largest
isosceles right triangle which can be inscribed within the fillet weld
cross- section. For unequal leg fillet welds, the leg lengths of the largest
rights triangle that can be inscribed within the fillet cross-section.
(b) Groove weld size – The joint penetration of a groove weld.
f. Theoretical Throat: It is the distance from the beginning of the joint root perpendicular to the
hypotenuse of the largest right triangle that can be inscribed within the
cross-section of the fillet weld. This dimension is based on the
assumption that the root opening is equal to zero.
Shown below are types of structural joints which are established by positions of the
connected material relative to one another. Lap, Tee and Butt or Groove Joints are the most
common.
Fig 14: Types of Welding Joints
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
2. Common Types of Welds: The most common types of welds are discussed below.
2.1. Fillet Weld: A fillet weld is the most common type of weld. The fillet weld is used to join two
pieces of flat steel at a 90-degree angle. A fillet weld is produced by running a weld bead at a
45-degree angle to a 90-degree corner; it resembles a triangle when viewed from the side.
Hence, fillet welds are theoretically triangular in cross-section. The weld is used to fill the area
where two pieces of steel meet, hence the name fillet weld.
It is used to make lap, corner and ‘T’ joints, the fillet weld is the most basic of welds. The
depth of the penetration, as in all welds, determines the strength of the fillet weld. It is
imperative when creating a fillet weld that the welding rod travel the same distance up both
sides of the joint when welding. Failure to get sufficient penetration on both pieces of the joint
will result in a weld that has far less strength than a weld that has equal distribution on both
sides of the joint.
Although this is a very common procedure, there is a number of parameters which are
necessary to take in special attention before doing such a welding, because among others, it
requires a higher heat transfer rate when compared to other types of joints of an equivalent
thickness, and with less experience welders, this could take to the lack of penetration and/or
fusion defects that are not easily identifiable through visual inspection or other non-destructive
techniques. Even excess welding which will lead to extra spending of consumable materials
will not result in achieving a higher global resistance.
Fig 15: Symbolic and Actual Profiles of a fillet weld
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
2.2. Butt or Groove Weld: Butt-welding is the process of joining two pieces of material together
along a single edge in a single plane. This process can be used on many types of materials,
though metal and thermoplastics are the most common. When two sheets of steel are laid
side-by-side and joined together along a single joint, this is an example of butt-welding.
Welding can be done using a large machine or a simple portable welder. The machine
applies heat to the two materials that are being joined, which causes them to melt slightly to
form a liquid. A filler material or a metal alloy is often added in between the two objects and
melted into the pool of liquid. When the heat from the welding machine is turned off, the
liquefied metal and filler will quickly solidify to form a single unit. When this process is done
correctly, the edges of each object are not distinguishable beneath the filler material.
There are three basic types of butt-welding, and each is chosen based on the thickness
of the objects being joined. For thin sheets of metal or plastic, a square weld joint can be used.
In this instance, the edges of the objects form 90-degree angles to one another, and can be
butted together like two building blocks. This is the simplest and most economical type of butt-
welding joint.
2.2.1. Types of Butt Welding: There are many types of butt welds, but all fall within one of
these categories:
(a) single welded butt joint,
(b) double welded butt joint, and
(c) open or closed butt joint.
A single welded butt joint is the
name for a joint that has only been welded
from one side. A double welded butt joint is
created when the weld has been welded
from both sides. With double welding, the
depths of each weld can vary slightly. A
closed weld is a type of joint in which the
two pieces that will be joined are touching
during the welding process. An open weld
is the joint type where the two pieces have
a small gap in between them during
welding.
Fig 16: Butt Joint Geometries
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
2.2.1.1. Square Butt joint:
The square-groove is a butt welding joint with the two pieces being flat and parallel to
each other. This joint is simple to prepare, economical to use, and provides satisfactory
strength, but is limited by joint thickness. The closed square butt weld is a type of square-
groove joint with no spacing in between the pieces. This joint type is common with gas and arc
welding.
For thicker joints, the edge of each member of the joint must be prepared to a particular
geometry to provide accessibility for welding and to ensure the desired weld soundness and
strength. The opening or gap at the root of the joint and the included angle of the groove
should be selected to require the least weld metal necessary to give needed access and meet
strength requirements.
2.2.1.2. Bevel Butt joint:
Single-bevel butt welds are welds where one piece in the joint is beveled and the other
surface is perpendicular to the plane of the surface. These types of joints are used where
adequate penetration cannot be achieved with a square-groove and the metals are to be
welded in the horizontal position. Double-bevel butt welds are common in arc and gas welding
processes. In this type both sides of one of the edges in the joint are beveled.
2.2.1.3 V-joints
Single-V butt welds are similar to a bevel joint, but instead of only one side having the
beveled edge, both sides of the weld joint are beveled. In thick metals, and when welding can
be performed from both sides of the work piece, a double-V joint is used. When welding thicker
metals, a double-V joint requires less filler material because there are two narrower V-joints
compared to a wider single-V joint. Also the double-V joint helps compensate for warping
forces. With a single-V joint, stress tends to warp the piece in one direction when the V-joint is
filled, but with a double-V-joint, there are welds on both sides of the material, having opposing
stresses, straightening the material.
2.2.1.4. J-joints
Single-J butt welds are when one piece of the weld is in the shape of a J that easily
accepts filler material and the other piece is square. A J-groove is formed either with special
cutting machinery or by grinding the joint edge into the form of a J. Although a J-groove is
more difficult and costly to prepare than a V-groove, a single J-groove on metal between a half
an inch and three quarters of an inch thick provides a stronger weld that requires less filler
material. Double-J butt welds have one piece that has a J shape from both directions and the
other piece is square.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
2.2.1.5. U-joints
Single-U butt welds are welds that have both edges of the weld surface shaped like a J,
but once they come together, they form a U. Double-U joints have a U formation on both the
top and bottom of the prepared joint. U-joints are the most expensive edge to prepare and
weld. They are usually used on thick base metals where a V-groove would be at such an
extreme angle, that it would cost too much to fill.
Butt welds are specified when a fillet weld is not appropriate for the job such as in the
case when the configuration of the pieces may not permit fillet welding or strength greater than
that provided by a fillet weld is required. However, butt welds also have their own
disadvantages. Fillet welds generally require less weld metal than butt welds. Additionally, fillet
welds do not generally require beveling and similar base metal preparation. As a result, fillet
welds are generally more economical to make than groove welds. Thus, fillet welds are
preferred.
2.3. Plug and Slot Welds: These are the least common type of welds. Plug weld is a type of
weld made by joining one metal part with a circular hole to another metal part positioned
directly beneath it whereas slot weld is a type of weld made by joining one metal part with an
elongated hole to another metal part positioned directly beneath it. Hence, a slot weld is similar
to plug weld, but the hole is elongated and may extend to the edge of a member without
closing. Weld metal is deposited in the holes which penetrates and fuses with the base metal
of the two members to form the joint.
Fig 17: Plug and Slot Welds
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
3. Welding Positions: There are four recognized welding positions which are given below.
Flat – The face of the weld is approximately horizontal and welding is performed from
above the joint.
Horizontal – The axis of the weld is horizontal.
Vertical – The axis is approximately vertical or in the upright position.
Overhead – Welding is performed from below the joint.
The flat position is preferred because it is easier and more efficient to weld in this
position.
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Fig 18: Welding Positions
4. Weld Symbols: Weld symbols are used to communicate the specific details and
requirements of each weld to the welder. These are included on fabrication and erection
drawings.
Fig 19: Weld Symbols Chart
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
Fig 20: Representation of Weld symbols in a drawing
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Chinmoy Pathak Choudhury
Assam Engineering College, Jalukbari
Guwahati - 781013
CHAPTER 3: STORAGE OF CEMENT BAGS IN WAREHOUSE
Portland cement should be protected against moisture at all times, whether the cement
is being transported on a truck or being held in storage or on the jobsite. For large construction
site, this is usually a secure storage area. Broadly, protection includes –
1. keeping out water which may fall as rain,
2. preventing water on the bed of truck from splashing upward against the sacks,
3. protection from water on the ground, such as puddles of rain or water from the mixing
operations.
All too often, cement bags may be observed sitting in water or on moist concrete or
receiving spray of water over the sacks. There is a very good reason for protecting cement
from exposure to water before it is batched into the mixture since Portland cement starts to
hydrate as soon as water touches it. Hydration of cement simply means that the cement
combines chemically with the water. It is not desirable that water combines with the cement
until the start of mixing the plaster, mortar or concrete because if the cement becomes moist
prior to mixing and placement, there will be some loss of strength and value in the ultimate
product. Portland cement is a valuable commodity and should be treated with reasonable care.
Cement should be held in a dry and protected area that has a dry floor. When rain or
mist is falling or imminent, the cement should be covered with a tarp before the load is
exposed to the weather. Generally cement bags are stacked closely together on pallets to
reduce air circulation and to raise the cement above any moisture sources. When removing
these bags for use, it should be sone done on a ‘first in, first out’ system. This means that the bags are stacked separately as they arrive eith the date of arrival placards attached to each
pile. The bags are to be rolled over when these need to be taken out for use.
Water-repellant bags may cause an ambiguity. They may be made repellant by having a
plastic coating on the shell of the bag or they may have a plastic liner to aid in keeping out the
moisture. One reason that the water-repellant bags must and do not have tiny perforations in
the walls to allow release of air from the sack during the bag-filling operation. Without those
holes to release air from the bag, filling would be virtually impossible using the typical packing
machines.