A Seminar report on automated orbital welding machines

1. i
DR. BABASAHEB AMBEDKAR MARATHWADA UNIVERSITY,
AURANGABAD.
A
Seminar report on
“Automated Orbital Welding Machines”
Submitted in partial fulfilment of the requirement for the degree of Bachelor of
Engineering (Mechanical)
Submitted by
Mr. Shubham B. Pandhare
Guided by
Prof. A. B. Humbe
Department of Mechanical Engineering
International Centre of Excellence in Engineering and Management,
Aurangabad
Year 2016-17

2. ii
CERTIFICATE
This is to certify that the seminar report entitled
“
Automated Orbital Welding Machines
”
Submitted by
Mr. Shubham B. Pandhare
Has completed as per the requirement of the Dr. Babasaheb Ambedkar Marathwada
University, Aurangabad in partial fulfilment of Degree
Bachelor of Engineering (Mechanical)
Guide Head of Department Director
Prof. A. B. Humbe Prof. S. M. Deshmukh Prof. Dilip Gour
Department of Mechanical Engineering,
International Centre of Excellence in Engineering and Management, Aurangabad
Year 2016-17

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ACKNOWLEDGEMENT
This seminar work has been carried out to meet the academic requirements of
Dr. BAMU University, Aurangabad for the completion of Bachelor of Engineering. I
would like to put on record, my appreciation and gratitude to all who have rendered
their support and input. Without them, it would not have been possible for me to
shape this study.
I have received immense guidance from Prof. A. B. Humbe, Guide and Prof.
S. M. Deshmukh, Head of the Mechanical Engineering Department. I would therefore
like to convey my sincere gratitude to them.
I would also like to thank Prof. Dilip Gour, Director of International Centre of
Engineering and Management, Aurangabad for their unending encouragement. All the
more, I would also like to thank him for having trust and confidence in me.
Finally, the most inspiring source, my parents, without their blessings,
continuous motivation, encouragement and moral support, it was not possible to
successfully complete this seminar work.
Thank You!
Name –Shubham B. Pandhare
Roll no. - 44035

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INDEX
Sr. No. Contents Page No.
i Title Page i
ii Certificate ii
iii Acknowledgement iii
iv Figure Index v
v Abstract vi
1. Introduction 1
2. Literature Review 4
3. Fundamental of Orbital welding
3.1 Closed head mechanism
3.2 Open head mechanism
7
4. Adaptive Orbital pipe welding 11
5. Seam tracking in Orbital pipe welding 13
6. Applications 16
7. Advantages 17
8. Disadvantages 18
9. Conclusion 19
10. Future Scope 20
11. References 21

5. v
FIGURE INDEX
Fig no. Title Page no.
3.1 Closed head mechanism 5
3.2 Open head welding machine for welding of pipes 7
5.1 Block diagram of the pipe welding system 11
5.2 The Four welding in the Orbital pipe welding 12
5.3 Welding torch degree of freedom 13

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ABSTRACT
Since the introduction of automatic orbital welding in pipeline application in
1961, significant improvements have been obtained in orbital pipe welding systems.
Requirement of more productive welding systems for pipeline application forces
manufacturers to innovate new advanced systems and welding processes for orbital
welding method.
Various methods have been used to make welding process adaptive, such as
visual sensing, passive visual sensing, real-time intelligent control, scan welding
technique, multi laser vision sensor, thermal scanning, adaptive image processing,
neural network model, machine vision, and optical sensing. Numerous studies are
reviewed and discussed in this Master’s thesis and based on a wide range of
experiments which already have been accomplished by different researches the vision
sensor are reported to be the best choice for adaptive orbital pipe welding system.
Also, in this study the most welding processes as well as the most pipe variations
welded by orbital welding systems mainly for oil and gas pipeline applications are
explained. The welding results show that Gas Metal Arc Welding (GMAW) and its
variants like Surface Tension Transfer (STT) and modified short circuit are the most
preferred processes in the welding of root pass and can be replaced to the Gas
Tungsten Arc Welding (GTAW) in many applications. Furthermore, dual-
tandem gas metal arc welding technique is currently considered the most efficient
method in the welding of fill pass.
Orbital GTAW process mostly is applied for applications ranging from single
run welding of thin walled stainless tubes to multi run welding of thick walled pipes.
Flux cored arc welding process is faster process with higher deposition rate and
recently this process is getting more popular in pipe welding applications.

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1. INTRODUCTION
Pipes and tubes welding are widely used in almost every engineering
application, Such as nuclear and thermal power plants, semiconductor fabrications, oil
and gas Industries and petrochemical plants. Therefore, the welding quality of
pipelines has a direct effect on the public safety and quality of the products. Oil and
gas Industry will be one of the key industries demanding extensive pipe welding due
to the prediction of a doubling of natural gas consumption over the next 20 years. This
increscent in requirements of pipe welding will require major investment in gas
transmission pipelines. Trend of using gas transmission with higher operating pressure
and higher strength steels increased demand of higher weld metals toughness and
quality. On the other hand, the cost of pipelines constructed should be considered to be
as low as possible.
Various automatic welding processes have been developed in pipe welding
industries to speed up welding process, producing better weld quality, and reducing
welding cost. Also, development in orbital pipe welding technology helps to maximize
the productivity of available welders and make welding process easier by employing a
variety of automated features, such as data collection, programming, and live weld
progress. Different factors, such as gravity, arc force, surface tension, heat
accumulation, joint preparation, and fit up precision effect welding pool during
automatic orbital pipe welding. Therefore, need of feedback and controlling system is
a vital part of orbital pipe system to ensure high welding quality.
Orbital welding is finding increasing value because it can present a cleaner,
virtually crevice surface and deliver highly repeatable and consistent quality welds.
Consequently, today, orbital welding has become a practical tool for many plant and
industrial operations due to the advanced technology. These industries can be named
as, boiler tube, food, dairy and beverage industries, nuclear piping, offshore, tube/pipe
fitting, valve, regulators, power, chemical, oil and gas, aerospace, biopharmaceutical,
medical, semiconductor, and pulp and paper industries, and for use in construction,
plant maintenance, distillation and refining operations

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2. LITERATURE REVIEW
According to Omkar Joshi, Dr.Arunkumar in “Overview of Orbital Welding
Technology” there are different welding technologies on welding in the market. The
orbital welding technology is the main topic of this paper. In this paper the history of
the orbital welding, the basic concepts of the orbital welding, the problems related to
the orbital welding are described. With that the solutions for the problems where
suggested in the paper. The orbital welding technique is changing from last decade but
still there are requirement of improvement in this technique related to the quality of
weld, efficiency, the productivity, simplicity. The overview of this technology
considering all above factors is considered in this paper.
In this paper, it is concluded that now a day’s competition in the production
industries is increases. The customers are demanding the products having good/high
quality. There are no chances for defects now in the product. To sustain in this
competitive life there is a need of the change in the production.
Optimizing the welding process improves weld quality; increases weld speed, and
reduce scrap and rework costs. By achieving these goals the companies can realize the
lower cost per product with a good quality and minimum delivery time. Using the
orbital welding technique with computer programming the control on the use of
electrode, input material, shield can etc. can be achieved easily.
As reported by Dongho Kim, Sung Choi, et.al in “Development of Orbital TIG
Welding Robot System for the Pipe” This study is about the orbital TIG welding robot
system which travels on the guide rail installed on the pipe, and welds and tracks the
pipe seam using the LVS (Laser Vision Sensor) joint profile data. The orbital welding
robot system consists of the robot, welder, controller, and LVS. Moreover we can
define the relationship between welding travel speed and wire feed speed, and we can
make the linear equation using the maximum and minimum amount of weld metal.
Using the linear equation we can determine the welding travel speed and the wire feed
speed accurately corresponding to the area of weld captured by LVS. We applied this
orbital TIG welding robot system to the stainless steel or duplex pipe on DSME
(Daewoo Shipbuilding and Marine Engineering Co. Ltd.,) shipyard and the result of
radiographic test are almost perfect.

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In this paper, it is concluded that in stainless steel welding requiring high
skilled welder, We, DSME robot team developed automatic welding robot installed on
the rail which is tangential direction to the circular pipe. Using LVS, obtaining cross
sectional surface area of pipe joint, uniform welding quality was guaranteed
controlling welding speed and wire feeding speed with the acquired surface area.
Furthermore, the database for stainless steel and duplex pipe was created and
successfully applied to our shipyard. Apart from stainless steel and duplex steel
materials, carbon steel, titanium, hastelloy, and etc. might be expected to the automatic
welding system developed in this study, and welding condition researched in this
study will be hopefully provided in those materials.
According to E.Roussel, P.Mazoyer In “Orbital Welding of Qrl Line in
Confined Environment” The QRL line supplies helium at 1.8 K to LHC magnets. AIR
LIQUIDE DTA was responsible for: installation of QRL lines: by orbital welding this
line has been installed in a circular underground tunnel of 27 km: the ring yields a
curve and introduces specific requirements for installation and orbital welding
preparation. This cryogenic line has been manufactured in reference to French code
CODAP, cat B, z = 0.85. Furthermore additional requirements were defined by CERN
the cryogenic line was divided by 8 sectors. For this project more than 15 000 orbital
welds and 600 manual welds have been realized to connect inner pipes.
In this paper, it is concluded that this industrial application on more than
15.000 welds is a rich lesson. We must take into account several comments and
conclusions. To benefit of orbital advantage it is necessary: To train teams “pipe
fitters” - complementary “welders” to obtain results of quality A permanent
maintenance is necessary The main advantages are as follows: The welding time is
reduced with orbital welding. Approximately 1.5 hours to orbital weld a junction and
more than 4 hours manually Choice of the orbital technology TIG which made it
possible to carry out the large majority of welds, without having resorts to highly
specialised operators. This choice allowed, after negotiation with the customer, to
reduce radio operator controls on orbital welding. Whereas manual welds were to be
inspected to 100%. This reduction contributed to the manufacturing lead time, because
X-ray in the tunnel stopped other works and displacements Level of repair is low,
especially for pipes with 2 mm wall thickness. With this welding configuration and for

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2.9 mm wall thickness we consider that single pass is an industrial upper limit. For
thicker pipe another technology should be proposed Choice of the CENTRATOR
machine is judicious: the double function “purging positioning” is very efficient.
As reported by N. I. S. Hussein er.al in “Tensile Strength of Orbital Welded
Mild Steel Tubes with Dissimilar Thickness” Lightweight trend leads to new trend of
welding in which optimizing tubes or pipes thicknesses due to its respective
workloads. Thinner tube can be used in parts with low working loads and thicker tube
for high working loads parts. In order to obtain a good weld, controlling the process
parameters such as welding current and welding speed become very crucial as it
significantly influences the mechanical properties. Thus, the purpose of this study is to
investigate the process-properties relationship of welded mild steel tube of dissimilar
thickness by using Metal Inert Gas (MIG) orbital welding. The effects of weld current
and jig rotational speed to the tensile properties of welded mild steel tubes were
studied. MIG welding was used to weld 26.70 mm diameter of mild steel tubes, which
has dissimilar inner diameter of 2.87 mm and 3.90 mm, respectively. The mechanical
properties were tested using Universal Tensile Machine (UTM) Instron 8802 model.
Design of Experiment (DoE) was used to design the experiment as well as to analyze
the data. It was found out that, tensile properties of welded tubes increase with
increasing of welding current between 60 and 80 A. On the other hand, increasing in
jig rotational speed between 40 and 50 rpm decreases the tensile properties of the
welded tubes. Empirical mathematical model was generated and verified.
In this paper, it is concluded that tensile strength of the welded tubes increases
with increasing of welding current between 60 and 80 A due to deeper penetration
which leads stronger weld joint. On the other hand, increasing in jig rotational speed
between 40 and 50 rpm decreases the tensile properties of the welded tubes due to
decreases in penetration which resulting weaker weld joint. This study also indicates
that welding current is the most significant parameter which influenced tensile
properties of welded mild steel tubes by MIG orbital welding compared to jig
rotational speed. The optimum parameter setting to get the maximum tensile strength
for this study was 80 A welding current and 40 rpm jig rotational speed. The
mathematical empirical model was developed and verified. Accuracy of the model was
96.8%.

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3. FUNDAMENTAL OF ORBITAL PIPE WELDING
Typically, orbital pipe welding machines are divided by closed head (full
function in place) and open head (full function orbital) . For welding of tubes, mostly
closed head machines are used and for welding of pipes with large diameters open
head machines are used.
3.1 Closed Head Mechanism (Full Function in Place)
For welds critical thin-wall tubing and pipes with small and medium-sized,
fabricators select a closed head device. Standard closed orbital weld heads can be used
for tube sizes from 1.6 to 162 mm (this number can be varies e.g. up to 200 mm or 6.3
to 203 mm) with wall thicknesses of up to 3.9 mm (0.4 to 12.7 mm). The head housing
in close head systems can be fixed or adapter types with limited range of
accommodation. Generally, during designing of welding heads, pipe standards and
limitations are taken into account by manufacturers, in order to make the range of a
single welding tool proportionately broad. For welding of particular applications
requiring extreme purity, thin walled aluminum tube, small diameter tubes, titanium
and stainless steels pipes, and so on, closed head welding system can be used.
Figure3.1 Closed Head Mechanism

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This system performs autogenous welding and the tubes are maintained in a
fixed position. The head cover the entire weld area while the tungsten electrode holder
moves along the joint driven by a small dc gear motor inside of head. The enclosed
chamber filled with inert gas (usually argon) which is responsible for shielding the end
part of the electrode and the fusion zone and the heated regions of the component 12 to
prevent the hot weld zone from oxidation. Arc length in this system remains fixed and
wire feed is and arc voltage control is not needed.
In welding of stainless steels with this mechanism, it should be considered that
inside surface of the pipe as well as outside should be protected from oxygen during
whole process. The reason is that stainless steel pipes content chromium and carbon
and during welding without proper protection will react with the oxygen to form
chromium carbides, commonly known as coking. To solve this problem internal bore
of the tube should be filled by an inert gas. This method is well known by back
purging.
3.2 Open Head Mechanism (Full Function Orbital)
Generally, open head systems are used for pipe welding with large diameters
and wall thicknesses (above 170 mm) and are considered full function heads.
There are two approaches for designing of this welding system. In the first one, within
of an external frame the welding heads mounted, introduced since 1960s, and its main
application is on lay barges, planned for the wide, open space of the USA and USSR.
In the second approach, welding system consists of welding head or “bugs”, bands or
chains, power supply, wire feeder, a programmable controller, shielding gas, and
coolant. Bands or chains are a device attached to the pipe or tube to move the head
around the joint. The controller may be mixed into the power supply and cable for
delivery of power. The welding heads mounted on bands or chains and travels the
circumference of the pipe along a track. In welding of thin wall tube, welding head
mostly consists of water cooling system to reduce heat input. The main application of
this welding system is onshore pipelines.

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Figure3.2 Open head welding machine for welding of pipes
By starting welding procedure by operator, the weld head and its inside
electrode house rotates in a precise orbit around the joint. The process is highly
controlled, and there are at least four servo controlled axes (travel, wire, arc voltage
control, and center steering) to ensure high quality welds that can be produced on a
consistent and repeatable basis. Precise controlling of all parameters in welding head
requires a state-of-the-art computer due to the complexity of this welding process. It
takes slightly more time to install these systems than to install an in-place head. This
type also may require a longer straight length of pipe for mounting. In orbital
Multi pass pipe welding, welding heads typically feature:
1. Torch rotation
2. Filler wire feed capability
3. Electronic control of arc length (arc voltage control)
4. Torch oscillation (weave) capability with programmable width, speed, and
independent end point (sidewall) dwell times.
The direction of welding head will change by changing of applications. If the position
of pipe weld is horizontal (5G) both, a double up and double down technique (6 to

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12O’clock CW, followed by 6 to 12 O’clock CCW) can be used. Also, weave
technique is usually used in the 5G position welding. To ensure complete sidewall
14 fusions, most of available systems are possible to be programmed dwell or delay
period at either end of the oscillation stroke. Orbital pipe welding with oscillation
motion is a useful feature in pipe welding industries.
One way to improve productivity in open head mechanism is to mount two welding
torches on one head. The improvement continues by reducing the distance between
two wires and using shared gas and weld pool. In a further development, it has been
proposed to replace the two torches of a system with tandem torches, creating the so
called “Dual-Tandem” process.

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4. ADAPTIVE ORBITAL PIPE WELDING
In many cases of orbital pipe welding process, tolerance of the work piece and
pipe thickness are so precise that the weld joint can be welded without any problem
while direction of welding is straight. In some cases, especially large diameter of
pipes, due to some reasons, such as pre-machining tolerance of the work piece, fit-up
precision and unfitness of the joint, there can be significant variations in weld joint
shapes and areas. This would result in poor welding appearance and possibly defects.
Consequently, an orbital welding system without feedback and controlling of the
welding parameters may easily result in poor welding quality, particularly, when the
work piece and welding joint are not prepared in good condition and are far away from
ideal requirements.
Develop and improve intelligent technologies for orbital pipe welding, such as
vision sensing, real-time intelligent control, and scan welding technique, may be an
effective approach to overcome this problem. This controlling of parameters is so
called adaptive welding which has been used with good results in industry for some
time. Adaptive welding systems have been called the Holy Grail of the industry.
Moreover, stability and accuracy of welding parameters controlling is very
important to make sure penetration is consistent and predictable. Today’s orbital
welding systems offer computer controls that store a variety of welding parameters
that can be called up as needed. Closed loop control of the welding parameters ensures
stable, constant, and accurate values with less room for error or defects. Adaptive,
practically means finding the centre of the joint (dynamic joint tracking) instead of
having a person always steer everything accurately. Also, in adaptive welding system,
controlling the weld power, wire feed, rotation (speed), pulse time, oscillation width,
torch motion and position, etc. are done automatically to help simplify operation and
produce a high quality weld. Three following basic steps counted in the study and
should be implemented to have an adaptive arc welding process:
In the first step, entire of the joint observed precisely and possible defects or
deviations in the groove walls are noticed. The system performs a comprehensive
inventory of the joint to be welded. In this observation, measurements, such as
temperature of the work piece and the uniformity of the groove are considered. The
system also keeps an inventory of previous welding passes and draws and uses it as a
knowledge base.

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Second step is recipe for decision making. The automated orbital welding
system organizes the effect of the different process variables according to importance.
And finally, integrating the rest of the system is the third step. Welding control system
require coupling of power source, torch motion, and wire feeder. These three
parameters, in some currently used welding systems are controlled separately for
accurate control of heat. This is important especially in welding of different pieces
with various asymmetrical or non-uniform heat capacities.
Recently, significant improvements have been obtained in adaptive orbital
welding system. Different studies have done in weld pool geometry sensing,
modelling and intelligent control of the weld quality and process monitoring. But still
needs have more efforts on this topic is sensed due to the complexity of welding
process, real-time and opening limits in orbital systems. Today, multi laser vision
sensors, thermal scanning, image processing, neural network model, machine vision,
or optical sensing are used in various fully automatic orbital welding system to
improve performance and reliability.
Generally, adaptive control of the welding parameters is not used in root pass
welding to guaranty weld penetration. Adaptive control of the orbital welding process
must be performed during the fill pass welding. There are two reasons for this: first,
sometimes joint area/height in on side of groove is larger than the other, therefore to
compensate this mismatch across the joint, weld parameters should be different on
each side of the joint. Secondly, sometimes in forming process of pipe especially in
pipes with large diameter, the joint volume on one side is much larger than the other.
Consequently, travel and wire feed speed; current/voltage level should be adjusted to
compensate for variations in the joint along the welding direction.

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5. SEAM TRACKING IN ORBITAL PIPE WELDING
For joining one pipe to the other, girth arc welding, which consists of the root
pass and the fill pass procedures, is prevalently performed. The welding process for
manufacturing pipe structures can be accomplished with automatic equipments that
have been partially mechanized only for fill pass welding and operated by a welding
operator. Due to machining or installation errors, it is difficult to ensure that the torch
has always aimed at the groove centre especially the large diameter pipe, which
requires manual adjustment during welding process. This method not only reduces the
efficiency of production but also cannot guarantee the quality of welds. Offline
programming of industrial robots can completed this work well, but it is a time
consuming and a costly tool. Some approach using visual sensors are studied for
tracking weld seams, which are not suitable for pipe welding when the question of the
signal noise is taken into account. The pipe welding robot, using laser vision sensor
which is not sensitive to noise and have high recognition precision, is able to
recognize and track horizontal and longitudinal dimensions, and fully meet the pipe
welding seam tracking and controlling demand.
A weld pool control technique with the vision sensor system for pipe welding
consisting of a laser vision sensor subsystem, a controller, an actuator, a charge
coupled device (CCD) camera, a long wave pass filter for lowering the arc intensity in
bead-on-plate welding, and welding equipment.
Figure 5.1 Block diagram of the pipe welding system

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In adaptive orbital pipe welding the great challenge is the position of welding torch
during welding process. As shown in Figure 45 the welding of pipe is divided into four
positions. The positions are the flat position, the overhead position, the ascending
vertical position and the vertical descendant position. In each one of them the optimum
parameters of the torch in relation to the welding pool are different.
Figure5.2 The four welding positions in the orbital pipe welding
On the other hand, to obtain desired result, precise control of torch angle in the
displacement plane during welding process is required. The reason is requirement of
pulling or pushing the welding pool by the torch, and in the perpendicular direction to
the movement, to correct the trajectory and to control the stick-out. Also, the lateral
angle movement in relation to the groove is an important factor in up or downhill pipe
welding. By correct position of torch in lateral angle, the effect of force of the gravity
can be reduced in the welding pool. Figure 46 shows a-four degrees of freedom in the
manipulator to get all the possible movements to be executed by the hand of a human
welder.

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Figure5.3 Welding torch degree of freedom
There have been various studies in the field of adaptive welding with similar or
different methods to improve welding productivity and quality. In the study, a fully
adaptive automatic welding system fills control for multi torch and multi pass SAW
was developed. The study developed a viable option of kinematic structure that is
capable to easily fulfil all the necessaries requirements. In the study the angle variation
effects on the metal transfer was studied on both transfer modes. Later the author
improved his work in by adding the effect of the input parameters on the drop
detaching around the pipe in GMAW and compensation of the gravity force effect
variation.

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6. APPLICATIONS
Aerospace:
The aerospace industry was the first to recognize the advantages of automated orbital
welding. The high pressure systems of a single aircraft can contain more than 1,500
welded joints, all automatically created with orbital equipment.
Boiler tube:
Boiler-tube installation and repair offer perfect applications for orbital welding.
Compact orbital weld heads can be clamped in place between rows of heat-exchanger
tubing.
Food, dairy and beverage industries:
These industries require consistent full penetration welds on all weld joints. For
maximum piping-system efficiency, the tubing and tube welds must be as smooth as
possible. Any pit, crevice, crack, or incomplete weld joint can trap the fluid flowing
inside the tubing, becoming a harbour for bacteria.
Nuclear piping:
The nuclear industry, with its severe operating environment and associated
specifications for high quality welds, has long been an advocate of orbital welding.
Pharmaceutical industry:
Pharmaceutical process lines and piping systems deliver high-quality water to their
processes. This requires high quality welds to ensure a source of water from the tubes
uncontaminated by bacteria, rust, or other contaminant. Orbital welding ensures full-
penetration welds with no overheating that could undermine the corrosion resistance
of the final weld zone.
Semiconductor industry:
The semiconductor industry requires piping systems with extremely smooth internal
surface finish to prevent contaminant build up on the tubing wall or weld joints. Once
large enough, a build-up of particulate, moisture, or contaminant could release and
ruin the batch process.
Tube/pipe fittings, valves, and regulators:
Hydraulic lines, liquid- and gas delivery systems, and medical systems all require
tubing with termination fittings. Orbital systems provide a means to ensure high
productivity of welding and optimum weld quality.

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7. ADVANTAGES
Productivity:
An orbital-welding system will drastically outperform manual welders, often enabling
the fabricator to cost-justify the equipment in a single job.
Quality and Consistency
The quality and repeatability of welds created by an orbital-welding system, driven by
the correct weld program, will be superior to that of manual welding. In applications
such as semiconductor or pharmaceutical tube welding, orbital welding is the only
means to achieve the required level of weld quality and consistency.
Skill level
Certified welders are increasingly hard to find. With orbital-welding equipment you
don’t need a certified welding operator; all it takes is a skilled mechanic with some
weld training.
Environment
Orbital welding can be executed even under harsh environmental conditions.
Restricted space or access, lack of visibility, presence of radiation; once the weld head
is positioned properly, the weld can be accomplished without problems from a safe
distance; often supported by a video transmission.
Orbital-welding equipment may be the only solution for applications where the
fabricator can’t rotate the tube or pipe for welding. It also finds use where access
limits the physical size of the welding device. Orbital-weld heads, for example may be
used within rows of boiler tubing, a difficult place for a manual welder to view the
weld joints and apply his welding torch.

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8. DISADVANTAGES
There are limitations to every type of welding, orbital included.
 To weld a variety of objects requires a variety or orbital welding heads, each
sized to fit different objects.
 Some objects are simply impossible to weld using an orbital welder, no matter
how many heads one has at hand.
 For this reason, orbital welding is best used as part of an arsenal, not as the
single tool in a welder’s belt.

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9. CONCLUSION
In orbital pipe welding method, the welding head rotates around a fixed
vertical or horizontal pipe. Orbital pipe welding technique could yield in significant
reductions in the processing time, skilled welder, and welding costs but improvements
in the joint quality. Other advantages involved with this method of welding mentioned
in this report are, portability, accessibility, high speed, precision, and cost
effectiveness.
Two types of orbital welding systems were explained in this study: closed head
and open head orbital welding systems. For welding of tubes, mostly closed head
machines are used and in the case of pipe welding with large diameters open head
machines are used. There are standard sizes of closed head welding system between
1.6 to 203 mm. Arc lengths during welding with this system remains fixed and the
process needs feeding of wire but controlling of arc voltage is not required. In welding
of stainless steels with this system, it should be considered that inside surface of the
pipe as well as outside should be protected from oxygen during whole process.
Generally, open head systems are used for pipe welding with large diameters and wall
thicknesses. Due to the complexity of this welding process, precise controlling of all
parameters in welding head requires a state-of-the-art computer.

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10. FUTURE SCOPE
Research and development activities for future applications, especially
regarding metals which so far cannot be welded with current welding processes is
going on. This forces welding systems to be advanced. Advanced orbital pipe welding
system consists of welding processes and sensing systems which together make the
welding process adaptive. Adaptive orbital welding systems should not only have the
ability to quickly be adapted due to new demands, but they are also expected to
efficiently change and reconfigure their facilities and even location. The future of
adaptive orbital pipe welding is gained by more inventions on faster welding process
as well as faster sensing system with cheaper mechanism. Downhill GMAW seems to
be the process of choice for the next few years. Hybrid laser arc welding and
FCAW are two processes required more investigations and attentions to obtain
higher productivity. Also, use of multi-torch and welding heads with different
processes at the same time can reduce the welding cycle time and consequently, more
economical benefits will be obtained.

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11. REFERENCES
• https://en.wikipedia.org/wiki/Orbital_welding
• Overview of Orbital Welding Technology by Omkar Joshi, Dr. Arunkumar
• Development of Orbital TIG Welding Robot System for the Pipe by Dongho
Kim, Sung Choi et.al
• Orbital Welding Of Qrl Line in Confined Environment By E.Roussel,
P.Mazoyer
• Tensile Strength of Orbital Welded Mild Steel Tubes with Dissimilar
Thickness by N. I. S. Hussein et.al
• Advanced Orbital Pipe Welding by Hamidreza Latifi