Mr. Romeo Rosimo SMAW process with 7018

Equipment

Equipment

SMAW system setup

Shielded metal arc welding equipment typically consists of a constant current welding power supply and an electrode, with an electrode holder, a ground clamp, and welding cables (also known as welding leads) connecting the two.

[edit] Power supply

The power supply used in SMAW has constant current output, ensuring that the current (and thus the heat) remains relatively constant, even if the arc distance and voltage change. This is important because most applications of SMAW are manual, requiring that an operator hold the torch. Maintaining a suitably steady arc distance is difficult if a constant voltage power source is used instead, since it can cause dramatic heat variations and make welding more difficult. However, because the current is not maintained absolutely constant, skilled welders performing complicated welds can vary the arc length to cause minor fluctuations in the current.^[13]

A high output welding power supply for SMAW and GTAW

Engine driven welder mounted in Field Service Truck

The preferred polarity of the SMAW system depends primarily upon the electrode being used and the desired properties of the weld. Direct current with a negatively charged electrode (DCEN) causes heat to build up on the electrode, increasing the electrode melting rate and decreasing the depth of the weld. Reversing the polarity so that the electrode is positively charged and the workpiece is negatively charged increases the weld penetration. With alternating current the polarity changes over 100 times per second, creating an even heat distribution and providing a balance between electrode melting rate and penetration.^[14]
Typically, the equipment used for SMAW consists of a step-down transformer and for direct current models a rectifier, which converts alternating current into direct current. Because the power normally supplied to the welding machine is high-voltage alternating current, the welding transformer is used to reduce the voltage and increase the current. As a result, instead of 220 V at 50 A, for example, the power supplied by the transformer is around 17–45 V at currents up to 600 A. A number of different types of transformers can be used to produce this effect, including multiple coil and inverter machines, with each using a different method to manipulate the welding current. The multiple coil type adjusts the current by either varying the number of turns in the coil (in tap-type transformers) or by varying the distance between the primary and secondary coils (in movable coil or movable core transformers). Inverters, which are smaller and thus more portable, use electronic components to change the current characteristics.^[15]
Electrical generators and alternators are frequently used as portable welding power supplies, but because of lower efficiency and greater costs, they are less frequently used in industry. Maintenance also tends to be more difficult, because of the complexities of using a combustion engine as a power source. However, in one sense they are simpler: the use of a separate rectifier is unnecessary because they can provide either AC or DC.^[16] However, the engine driven units are most practical in field work where the welding often must be done out of doors and in locations where transformer type welders are not usable because there is no power source available to be transformed.
In some units the alternator is essentially the same as that used in portable generating sets used to supply mains power, modified to produce a higher current at a lower voltage but still at the 50 or 60Hz grid frequency. In higher-quality units an alternator with more poles is used and supplies current at a higher frequency, such as 400Hz. The smaller amount of time the high-frequency waveform spends near zero makes it much easier to strike and maintain a stable arc than with the cheaper grid-frequency sets or grid-frequency mains-powered units.

[edit] Electrode

Various welding electrodes and an electrode holder

The choice of electrode for SMAW depends on a number of factors, including the weld material, welding position and the desired weld properties. The electrode is coated in a metal mixture called flux, which gives off gases as it decomposes to prevent weld contamination, introduces deoxidizers to purify the weld, causes weld-protecting slag to form, improves the arc stability, and provides alloying elements to improve the weld quality.^[17] Electrodes can be divided into three groups—those designed to melt quickly are called "fast-fill" electrodes, those designed to solidify quickly are called "fast-freeze" electrodes, and intermediate electrodes go by the name "fill-freeze" or "fast-follow" electrodes. Fast-fill electrodes are designed to melt quickly so that the welding speed can be maximized, while fast-freeze electrodes supply filler metal that solidifies quickly, making welding in a variety of positions possible by preventing the weld pool from shifting significantly before solidifying.^[18]
The composition of the electrode core is generally similar and sometimes identical to that of the base material. But even though a number of feasible options exist, a slight difference in alloy composition can strongly impact the properties of the resulting weld. This is especially true of alloy steels such as HSLA steels. Likewise, electrodes of compositions similar to those of the base materials are often used for welding nonferrous materials like aluminium and copper.^[19] However, sometimes it is desirable to use electrodes with core materials significantly different from the base material. For example, stainless steel electrodes are sometimes used to weld two pieces of carbon steel, and are often utilized to weld stainless steel workpieces with carbon steel workpieces.^[20]
Electrode coatings can consist of a number of different compounds, including rutile, calcium fluoride, cellulose, and iron powder. Rutile electrodes, coated with 25%–45% TiO₂, are characterized by ease of use and good appearance of the resulting weld. However, they create welds with high hydrogen content, encouraging embrittlement and cracking. Electrodes containing calcium fluoride (CaF₂), sometimes known as basic or low-hydrogen electrodes, are hygroscopic and must be stored in dry conditions. They produce strong welds, but with a coarse and convex-shaped joint surface. Electrodes coated with cellulose, especially when combined with rutile, provide deep weld penetration, but because of their high moisture content, special procedures must be used to prevent excessive risk of cracking. Finally, iron powder is a common coating additive, as it improves the productivity of the electrode, sometimes as much as doubling the yield.^[21]
To identify different electrodes, the American Welding Society established a system that assigns electrodes with a four- or five-digit number. Covered electrodes made of mild or low alloy steel carry the prefix E, followed by their number. The first two or three digits of the number specify the tensile strength of the weld metal, in thousand pounds per square inch (ksi). The penultimate digit generally identifies the welding positions permissible with the electrode, typically using the values 1 (normally fast-freeze electrodes, implying all position welding) and 2 (normally fast-fill electrodes, implying horizontal welding only). The welding current and type of electrode covering are specified by the last two digits together. When applicable, a suffix is used to denote the alloying element being contributed by the electrode.^[22]
Common electrodes include the E6010, a fast-freeze, all-position electrode with a minimum tensile strength of 60 ksi (410 MPa) which is operated using DCEP. Its cousin E6011 is similar except that it is used with alternating current. E7024 is a fast-fill electrode, used primarily to make flat or horizontal welds using AC, DCEN, or DCEP. Examples of fill-freeze electrodes are the E6012, E6013, and E7014, all of which provide a compromise between fast welding speeds and all-position welding.^[23]

[edit] Process variations

Though SMAW is almost exclusively a manual arc welding process, one notable process variation exists, known as gravity welding or gravity arc welding. It serves as an automated version of the traditional shielded metal arc welding process, employing an electrode holder attached to an inclined bar along the length of the weld. Once started, the process continues until the electrode is spent, allowing the operator to manage multiple gravity welding systems. The electrodes employed (often E6027 or E7024) are coated heavily in flux, and are typically 28 in (0.8 m) in length and about 0.25 in (6 mm) thick. As in manual SMAW, a constant current welding power supply is used, with either negative polarity direct current or alternating current. Due to a rise in the use of semiautomatic welding processes such as flux-cored arc welding, the popularity of gravity welding has fallen as its economic advantage over such methods is often minimal. Other SMAW-related methods that are even less frequently used include firecracker welding, an automatic method for making butt and fillet welds, and massive electrode welding, a process for welding large components or structures that can deposit up to 60 lb (27 kg) of weld metal per hour

Operation

Operation

SMAW weld area

To strike the electric arc, the electrode is brought into contact with the workpiece by a very light touch with the electrode to the base metal then is pulled back slightly. This initiates the arc and thus the melting of the workpiece and the consumable electrode, and causes droplets of the electrode to be passed from the electrode to the weld pool. As the electrode melts, the flux covering disintegrates, giving off shielding gases that protect the weld area from oxygen and other atmospheric gases. In addition, the flux provides molten slag which covers the filler metal as it travels from the electrode to the weld pool. Once part of the weld pool, the slag floats to the surface and protects the weld from contamination as it solidifies. Once hardened, it must be chipped away to reveal the finished weld. As welding progresses and the electrode melts, the welder must periodically stop welding to remove the remaining electrode stub and insert a new electrode into the electrode holder. This activity, combined with chipping away the slag, reduce the amount of time that the welder can spend laying the weld, making SMAW one of the least efficient welding processes. In general, the operator factor, or the percentage of operator's time spent laying weld, is approximately 25%.^[6]
The actual welding technique utilized depends on the electrode, the composition of the workpiece, and the position of the joint being welded. The choice of electrode and welding position also determine the welding speed. Flat welds require the least operator skill, and can be done with electrodes that melt quickly but solidify slowly. This permits higher welding speeds. Sloped, vertical or upside-down welding requires more operator skill, and often necessitates the use of an electrode that solidifies quickly to prevent the molten metal from flowing out of the weld pool. However, this generally means that the electrode melts less quickly, thus increasing the time required to lay the weld.^[7]

[edit] Quality

The most common quality problems associated with SMAW include weld spatter, porosity, poor fusion, shallow penetration, and cracking. Weld spatter, while not affecting the integrity of the weld, damages its appearance and increases cleaning costs. It can be caused by excessively high current, a long arc, or arc blow, a condition associated with direct current characterized by the electric arc being deflected away from the weld pool by magnetic forces. Arc blow can also cause porosity in the weld, as can joint contamination, high welding speed, and a long welding arc, especially when low-hydrogen electrodes are used. Porosity, often not visible without the use of advanced nondestructive testing methods, is a serious concern because it can potentially weaken the weld. Another defect affecting the strength of the weld is poor fusion, though it is often easily visible. It is caused by low current, contaminated joint surfaces, or the use of an improper electrode. Shallow penetration, another detriment to weld strength, can be addressed by decreasing welding speed, increasing the current or using a smaller electrode. Any of these weld-strength-related defects can make the weld prone to cracking, but other factors are involved as well. High carbon, alloy or sulfur content in the base material can lead to cracking, especially if low-hydrogen electrodes and preheating are not employed. Furthermore, the workpieces should not be excessively restrained, as this introduces residual stresses into the weld and can cause cracking as the weld cools and contracts.^[8]

[edit] Safety

SMAW welding, like other welding methods, can be a dangerous and unhealthy practice if proper precautions are not taken. The process uses an open electric arc, which presents a risk of burns which are prevented by personal protective equipment in the form of heavy leather gloves and long sleeve jackets. Additionally, the brightness of the weld area can lead to a condition called arc eye, in which ultraviolet light causes inflammation of the cornea and can burn the retinas of the eyes. Welding helmets with dark face plates are worn to prevent this exposure, and in recent years, new helmet models have been produced that feature a face plate that self-darkens upon exposure to high amounts of UV light. To protect bystanders, especially in industrial environments, transparent welding curtains often surround the welding area. These curtains, made of a polyvinyl chloride plastic film, shield nearby workers from exposure to the UV light from the electric arc, but should not be used to replace the filter glass used in helmets.^[9]
In addition, the vaporizing metal and flux materials expose welders to dangerous gases and particulate matter. The smoke produced contains particles of various types of oxides. The size of the particles in question tends to influence the toxicity of the fumes, with smaller particles presenting a greater danger. Additionally, gases like carbon dioxide and ozone can form, which can prove dangerous if ventilation is inadequate. Some of the latest welding masks are fitted with an electric powered fan to help disperse harmful fumes.^[10]

[edit] Application and Materials

Shielded metal arc welding is one of the world's most popular welding processes, accounting for over half of all welding in some countries. Because of its versatility and simplicity, it is particularly dominant in the maintenance and repair industry, and is heavily used in the construction of steel structures and in industrial fabrication. In recent years its use has declined as flux-cored arc welding has expanded in the construction industry and gas metal arc welding has become more popular in industrial environments. However, because of the low equipment cost and wide applicability, the process will likely remain popular, especially among amateurs and small businesses where specialized welding processes are uneconomical and unnecessary.^[11]
SMAW is often used to weld carbon steel, low and high alloy steel, stainless steel, cast iron, and ductile iron. While less popular for nonferrous materials, it can be used on nickel and copper and their alloys and, in rare cases, on aluminium. The thickness of the material being welded is bounded on the low end primarily by the skill of the welder, but rarely does it drop below 0.05 in (1.5 mm). No upper bound exists: with proper joint preparation and use of multiple passes, materials of virtually unlimited thicknesses can be joined. Furthermore, depending on the electrode used and the skill of the welder, SMAW can be used in any position.

Shielded metal arc welding

SMAW welding in the field

Shielded metal arc welding

Shielded metal arc welding (SMAW), also known as manual metal arc (MMA) welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode coated in flux to lay the weld. An electric current, in the form of either alternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination.
Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of the world's most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, SMAW continues to be used extensively in the construction of steel structures and in industrial fabrication. The process is used primarily to weld iron and steels (including stainless steel) but aluminium, nickel and copper alloys can also be welded with this method.

welding inspector 3.0

OBJECTIVE

• Understand factor, which influence the quality of fusion welds in steel.
• Recognize characteristics of commonly used welding processes in relation to quality control
• Interpret drawing instruction and symbols to ensure that specifications are met.
• Set up and report on inspection of welds, macro sections and other mechanical test.
• Assess and report on welds to acceptable levels.
• Confirm that incoming materials meet stipulated requirements and recognize the effects on weld quality of departure from specification.
• Be in position to pass the PCN Welding Inspector 3.0 examination

COURSE CONTENTS

• Visual inspection procedures
• Relevant codes of practice
• Terms and definitions
• Welding process and typical welding defects
• Weld measurements
• Typical documentation and requirements
• Practical inspection and reporting

WHO SHOULD ATTEND

Inspection Engineers and supervisory staff, QA/QC Inspectors. The course is ideal for inspectors require preparation for PCN examination as Welding Inspector (3.0)

DURATION	:	3 days
TIME	:	9.00 am - 5.00 pm OR 6.00 PM - 10.00 PM
VENUE	:	PUSPATRI
METHODOLOGY	:	Lecture, hands-on, open discussions, video presentation, practical demonstration

MAGNETIC PARTICLE TESTING

OBJECTIVES :

At the end of the course, attendees shall be able to:

• Explain the basic principles of penetrant inspection
• Carry out penetrant inspection using color contrast & fluorescent method
• Write clear and concise inspection instructions & report
• Meets syllabus requirements for Level 2-PCN

COURSE CONTENT

The following are some of the training contents with regards to Magnetic Particle Testing

• Surface Preparation
• Safety Aspects
• Penetrant Systems
• Physical Principles Of Penetrants
• Principles Of Penetrant Testing
• Penetrant Application Methods
• Removal Of Excees Penetrant
• Emulsifiers/Removers And Their Importance
• Developers And Their Importance
• Drying Methods
• Inspection Techniques
• Methods For Interpreting Of Indications
• Methods For Recording Of Indications
• Effect Of Contamination & Abuse
• Penetrant Testing Equipment
• Effluent Treatment
• Control Checks
• Use Of Test Pieces
• Product Technology
• Practical Penetrant Testing Of Various Specimen-Welds,Casting,Forged And Others
• Tuition Ends With A Written & Practical Test

DURATION	:	4 days
TIME	:	9.00 am - 5.00 pm OR 6.00 PM - 10.00 PM
VENUE	:	PUSPATRI
METHODOLOGY	:	Lecture, hands-on, open discussions, video presentation, practical demonstration

Ultrasonic Testing

OBJECTIVES

At the end of the course, attendees shall be able to:

• Understand the ultrasonic testing techniques
• Calibrate ultrasonic equipment
• Measure thickness of materials
• locate and evaluate lamination
• Select the suitable probe types for related application
• Report on the location and size of defects in component tested
• Interpret the code requirements
• Meets the syllabus requirements of Level 1 & 2-PCN

COURSE CONTENT

The following are some of the training contents with regards to Ultrasonic Testing

• Principles Of Sound
• Ultrasonic
• Flaw Detector
• Transducers
• Materials And Their Effects On The Propagation Of Sound
• Practical In Equipment Set Up
• Usage Of Various Probes And Reference Blocks
• Sensitivity Setting
• Calibrations
• Indentifying Various Signals Of Defects And Spurious
• Practical Exercises On Test Specimens Containing Simulated Flaws
• Practical Exercises On Test Specimens Containing Actual Flaws
• Practical Ultrasonic Testing Of Various Related Specimens
• Codes And Specifications
• Report Writing
• Instruction Writing

DURATION	:	10 days
TIME	:	9.00 am - 5.00 pm OR 6.00 pm - 11.00 pm
VENUE	:	PUSPATRI
METHODOLOGY	:	Lecture, hands-on, open discussions, video presentation, practical demonstration

API Inspector

OBJECTIVES

To recognize working professionals who are knowledgeable of industry inspection codes and are performing their jobs in accordance with those codes. Through our Witnessing Programs, API provides knowledgeable and experienced witnesses to observe critical material and equipment testing and verification

COURSE CONTENT

The following are some of the processes involved with regards to API Inspector to recognized standard.

Organization And Certification Requirements

• Types And Definitions Of Maintenance Inspections
• Types Process Corrosion And Deterioration
• Modes Of Mechanical, Thermal And High Temperature Deteoration
• Pressure Vessel Materials And Fabrication Problems
• Welding On Pressure Vessels
• Non-Destructive Testing (NDE) Methods
• Corrosion And Minimum Thickness Evaluation
• Estimated Remaining Life
• Inspection Interval Determination And Issues Affecting Intervals
• Inspecting Relief Devices
• Repairs And Alteration To Pressure Vessels
• Rerating Pressure Vessels
• Pressure Testing After Repairs, Alteration And Rerating
• Inspection Records And Reports
• Maintenance Inspection Safety Practices

DURATION	:	5 days
TIME	:	9.00 am - 5.00 pm or 6.00 pm - 11.00 pm
VENUE	:	PUSPATRI
METHODOLOGY	:	Lecture, hands-on, open discussions, video presentation, practical demonstration

A BASIC GUIDE OF ARC WELDING ELECTRODES

 INTRODUCTION

There are many different types of electrodes used in the shielded metal arc welding, (SMAW) process. The intent of this guide is to help with the identification and selection of these electrodes.

ELECTRODE IDENTIFICATION

Arc welding electrodes are identified using the A.W.S, (American Welding Society) numbering system and are made in sizes from 1/16 to 5/16 . An example would be a welding rod identified as an 1/8" E6011 electrode. The electrode is 1/8" in diameter
The "E" stands for arc welding electrode.
Next will be either a 4 or 5 digit number stamped on the electrode. The first two numbers of a 4 digit number and the first 3 digits of a 5 digit number indicate the minimum tensile strength (in thousands of pounds per square inch) of the weld that the rod will produce, stress relieved. Examples would be as follows:
E60xx would have a tensile strength of 60,000 psi E110XX would be 110,000 psi
The next to last digit indicates the position the electrode can be used in.

1. EXX1X is for use in all positions
2. EXX2X is for use in flat and horizontal positions
3. EXX3X is for flat welding

The last two digits together, indicate the type of coating on the electrode and the welding current the electrode can be used with. Such as DC straight, (DC -) DC reverse (DC+) or A.C.
I won't describe the type of coatings of the various electrodes, but will give examples of the type current each will work with.

ELECTRODES AND CURRENTS USED

• EXX10 DC+ (DC reverse or DCRP) electrode positive.
• EXX11 AC or DC- (DC straight or DCSP) electrode negative.
• EXX12 AC or DC-
• EXX13 AC, DC- or DC+
• EXX14 AC, DC- or DC+
• EXX15 DC+
• EXX16 AC or DC+
• EXX18 AC, DC- or DC+
• EXX20 AC ,DC- or DC+
• EXX24 AC, DC- or DC+
• EXX27 AC, DC- or DC+
• EXX28 AC or DC+

CURRENT TYPES

SMAW is performed using either AC or DCcurrent. Since DC current flows in one direction, DC current can be DC straight, (electrode negative) or DC reversed (electrode positive). With DC reversed,(DC+ OR DCRP) the weld penetration will be deep. DC straight (DC- OR DCSP) the weld will have a faster melt off and deposit rate. The weld will have medium penetration.
Ac current changes it's polarity 120 times a second by it's self and can not be changed as can DC current.

ELECTRODE SIZE AND AMPS USED

The following will serve as a basic guide of the amp range that can be used for different size electrodes. Note that these ratings can be different between various electrode manufactures for the same size rod. Also the type coating on the electrode could effect the amperage range. When possible, check the manufactures info of the electrode you will be using for their recommended amperage settings.

Electrode Table
ELECTRODE DIAMETER (THICKNESS)	AMP RANGE	PLATE
1/16"	20 - 40	UP TO 3/16"
3/32"	40 - 125	UP TO 1/4"
1/8	75 - 185	OVER 1/8"
5/32"	105 - 250	OVER 1/4"
3/16"	140 - 305	OVER 3/8"
1/4"	210 - 430	OVER 3/8"
5/16"	275 - 450	OVER 1/2"

Note! The thicker the material to be welded, the higher the current needed and the larger the electrode needed.

SOME ELECTRODE TYPES

This section will briefly describe four electrodes that are commonly used for maintenance and repair welding of mild steel. There are many other electrodes available for the welding of other kinds of metals. Check with your local welding supply dealer for the electrode that should be used for the metal you want to weld. E6010 This electrode is used for all position welding using DCRP. It produces a deep penetrating weld and works well on dirty,rusted, or painted metals
E6011 This electrode has the same characteristics of the E6010, but can be used with AC and DC currents.
E6013 This electrode can be used with AC and DC currents. It produces a medium penetrating weld with a superior weld bead appearance.
E7018 This electrode is known as a low hydrogen electrode and can be used with AC or DC. The coating on the electrode has a low moisture content that reduces the introduction of hydrogen into the weld. The electrode can produce welds of x-ray quality with medium penetration. (Note, this electrode must be kept dry. If it gets wet, it must be dried in a rod oven before use.)
It is hoped that this basic information will help the new or home shop welder identify the various types of electrodes and select the correct one for their welding projects.

BASIC WELD SYMBOLS

a. General. Weld symbols are used to indicate the welding processes used in metal joining operations, whether the weld is localized or "all around", whether it is a shop or field weld, and the contour of welds. These basic weld symbols are summarized below and illustrated in figure 3-3.

b. Arc and Gas Weld Symbols. See figure 3-3.

c. Resistance Weld Symbols. See figure 3-3.

d. Brazing, Forge, Thermit, Induction, and Flow Weld Symbols.

(1) These welds are indicated by using a process or specification reference in the tail of the welding symbol as shown in figure 3-4.



(2) When the use of a definite process is required (fig. 3-5), the process may be indicated by one or more of the letter designations shown in tables 3-1 and 3-2.







NOTE

Letter designations have not been assigned to arc spot, resistance spot, arc seam, resistance seam, and projection welding since the weld symbols used are adequate.



(3) When no specification, process, or other symbol, the tail may be omitted (fig. 3-6). reference is used with a welding



e. Other Common Weld Symbols. Figures 3-7 and 3-8 illustrate the weld-all-around and field weld symbol, and resistance spot and resistance seam welds.





f. Supplementary Symbols. These symbols are used in many welding processes in congestion with welding symbols and are used as shown in figure 3-3.

ELMENTS OF A WELDING SYMBOL

A distinction is made between the terms "weld symbol" and "welding symbol". The weld symbol (fig. 3-3) indicates the desired type of weld. The welding symbol (fig. 3-2) is a method of representing the weld symbol on drawings. The assembled "welding symbol" consists of the following eight elements, or any of these elements as necessary: reference line, arrow, basic weld symbols, dimensions and other data, supplementary symbols, finish symbols, tail, and specification, process, or other reference. The locations of welding symbol elements with respect to each other are shown in figure 3-2.