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PRACTICAL WELDING LETTER, Issue #011-- Pipe Welding, Copper Alloy Filler Metals, Defects and Failure July 01, 2004 |
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| We hope you will find this Letter interesting and useful. Let us know what you think of it. Practical Issues, Creative Solutions
This publication brings to the readers practical answers --------------------------------------------------------------------------------
You are urged to pass-along this publication to your -------------------------------------------------------------------------------- Date: July 2004 - Practical Welding Letter - Issue No. 11
-----------------------------TABLE of CONTENTS-------------------------------
1 - Introduction 2 - Article: Pipe Welding 3 - How to do it well: Strength of Stainless Spot Welds 4 - Filler Metal: Copper Alloys 5 - Online Press: recent Welding related Articles 6 - Terms and Definitions Reminder 7 - Article: Failures from Weld Discontinuities 8 - Site Updating 9 - Short Items 10 - Explorations: beyond the Welder 11 - Contribution: Links, Mistakes 12 - Testimonials 13 - Correspondence: a few Comments 14 - Bulletin Board -------------------------------------------------------------------------------------
1 - Introduction It will not come as a big surprise that the number of subscribers to this publication is now exceeding 1050. Unfortunately it seems that not all recipients really care to read Practical Welding Letter or have any interest in what is in here, possibly because it is not targeted enough to their needs. But we continue writing for the ones who find some worth in our toil, and for those who take their time to express to us their appreciation. Let us have your comments and wishes and please inform your other friends and acquaintances of what is here available at no cost. Click here. Time has come to deal with Pipe Welding, a most important manufacturing sector that fuels large industrial initiatives. The impression, as conveyed by people experienced in joining this type of fluid moving facilities, is that the art of Pipe Welding is not managed as it should, and much of the results are left to happen the best they can, without concerted efforts to obtain optimum results. The sad conclusion is that the negative economic impact of this lack of management does not seem to concern those who should have the most to gain from redressing the situation. We refer interested readers to three articles available online on the said argument, to enlarge scope and depth of understanding. A short note on the strength of spot welds in stainless steel sheets helps deciding if they are acceptable, even if the exact tensile strength at rupture is not known. Filler metal selection for welding Copper Alloys seems easy: it should help, however, to know something on alloying elements and their influence, and on the difficulties brought forward by elevated thermal conductivity. Site Update points to the last page recently added to the Site. It deals with a process best adapted to mass production of high quality welded joints. The basics should be known, to compare it with competing solutions. An article is devoted to discontinuities and to the dangers they pose to the integrity of welded structures. New approaches are briefly outlined capable to give scientific justification to the establishment of acceptance requirements. Other Departments fall in place as usual. They should add some items of interest and some hints, possibly capable to start inquiries in new fields and directions. Tell us what you think and send us your feedback. Click here. ------------------------------------------------------------------------------------- 2 - Article: Pipe Welding Pipe Welding in oil refineries, in power station and in chemical plants represents a very important sector of manufacturing, whose requirements are established in formal Codes. In the USA the most common document is that of the American Petroleum
Institute An introductory document explaining the requirements is available from AWS In Europe BS EN 287-1 Revision: 04 The techniques for welding differ according to the position assumed by the pipe to be welded. There are four main positions described for welding pipes. G stands for Groove weld, F for Fillet weld. Position 1G designates a rotating horizontal pipe in a mechanized set up. This position permits performing the circumferential joint in flat position for the weld. It is the preferred position, whenever applicable, because it permits the highest weld deposition rate. Position 2G designates a vertical pipe, where a horizontal weld has to be performed. No rotation is considered in that it makes no difference to the welding process. Position 5G designates a fixed horizontal pipe, presenting the weld in different locations, from flat on top to vertical on the sides and finally to overhead for the bottom position. Position 6G indicates a fixed inclined tube, generally at 45 degrees from the horizontal. Position 6GR means the same but Restricted, indicating that a Restriction Ring is in place, hindering somewhat the freedom of approach of the welder. Pipeline Welding and Inspection Courses are available from specialized Institutes. A few useful references are presented by a commercial firm. See: An interesting article by another commercial firm It has been affirmed that the passage from stick welding (SMAW) or sometimes from GTAW (Tig) for the root pass at least, to more productive GMAW (Mig) has been hindered by erroneous interpretation of old Code requirements that seemed to prohibit the use of short circuit transfer mode for root pass GMAW of pipes, and possibly also by inadequate welding, as discussed further on in this article. The correct interpretation requires only demonstration of the adequacy of the proposed procedure through proper testing and qualification. An article on "Optimizing repair welding in oil refineries" was presented in the
press section of Issue #05 of PWL for January 2004. It is now available at: As discussed in an article titled: "In service weld defects: repair, replace or
do nothing?", that you can read at: This should not surprise. In many cases, although not having undergone the formal analysis predicated by Fitness for Service (click for definition, then close new window to come back) design principles, there was evidently a factor of safety built in and possibly some plain good luck that prevented catastrophic failures to occur until present time at least. It has been reported (see Note 1) that in practice a large proportion of GMA welded pipes supplied and commissioned in industrial plants possibly present lack of fusion defects not revealed by the routine Non Destructive Testing methods applied during manufacturing.
Note 1: Ed Craig - A Management and Engineers Guide to Mig Welding Quality-Cost-Training, page 435. Available from http://www.weldreality.com Lack of fusion discontinuities, as created by improper GMAW, can only be detected if the radiographic method employed is especially tuned to find out those defects (see Note 2). These may appear on the film only in certain directions of exposure (parallel to the long dimension of the defect and to the original groove surface). They could be made evident by integrative procedures including also ultrasonic testing but the additional cost has to be justified by more severe requirements. Note 2: See for example a study on "The Reliability of Radiography of Thick Section Welds" at http://www.twi.co.uk/j32k/protected/band_8/spimjul99.html
The origins of this situation are attributed to a pervasive lack of GMAW expertise in the welding industry, starting from management, to non prepared welding decision makers, to untrained supervisors and finally to welders. Contributes to this unfortunate situation the requirement of major codes of a limited x-ray coverage, usually 10%, prone to manipulations in the selection of the representative welds submitted to testing. The presence of lack of fusion in GMAW pipe welds derives from the tendency of welders to prefer "their way" of selecting settings instead of the application of standard and proven parameters. Welders and supervisors are generally more attentive to surface appearance than to the intrinsic quality of welds. The responsibility for this state of things rests on management's shoulders but it is not sufficiently determinant to produce improvement. One of the easiest and most significant destructive tests that should be conducted even before presenting Welding Procedure Specification (WPS) test pieces for obtaining a PQR (Procedure Qualification Record) is, as suggested by Ed Craig (see Note 1 above) on page 449, to perform a series of transversal cuts of the joint, distant 25 mm from each other, and then prepare them for macrographic inspection after grinding, polishing and etching each of the sections. This extra work presumes an attitude in management (or in the purchaser) inquisitive of the real quality of the pipe welds to be provided by the contractor. Practical tutorial information on Pipe welding can be found in: The most important requirement for correct and profitable pipe welding, as proposed by Ed Craig in his book, pointed out in above Note 1, is the development of a Weld Process Control Program, (page 490), that helps in finding and demonstrating the best parameters for consistent high quality of pipe welding in an industrial environment. Upon qualification it should be strictly adhered to. This attitude presuppose a will to provide improved welding expertise to all levels involved, much the same as it would be pursued for any other more classic manufacturing technology. ------------------------------------------------------------------------------------- 3 - How to do it well: Strength of Stainless Spot Welds. Q - How to judge of the adequacy of spot welds in stainless steel sheets? A - Austenitic Stainless Steel sheets are easily spot welded. However, just by observing how many common household implements made of stainless steel fail sometimes in spot welds, one would think that it may be difficult to obtain and to judge of their strength. Given standard single lap spot weld coupons, it appears that the minimum strength reported for each spot weld in accepted Specifications has no real interest, because good spot welds will not break in the weld. When tested in tension they will rather fail in the material around the weld, by tearing a button in one half of the specimen and leaving a hole in the other half. This is a good result even if the tensile test value at rupture is not known exactly. ------------------------------------------------------------------------------------- 4 - Filler Metals: Copper Alloys The AWS classification of copper base Filler Metals is specified in the following standards: AWS A5.6 - Specification for Covered Copper and Copper Alloy Arc Welding Electrodes. AWS A5.7 - Specification for Copper and Copper Alloy Bare Welding Rods and Electrodes AWS A5.27 - Specification for Copper and Copper Alloy Rods for Oxyfuel Gas Welding WARNING: As Copper Alloys may include volatile, low temperature boiling, toxic elements, it is imperative to implement effective ventilation systems for the protection of the operators involved. Copper Filler Metals. The electrodes and rods used to weld copper, primarily deoxidized and electrolytic tough pitch (ETP) copper, are designated as ERCu and have a minimum copper content of 98%. Silicon and phosphor are added as deoxidizers. These filler metals, which can be used with GMAW, GTAW, and PAW processes, have electrical conductivity ratings of 25 to 40% IACS. Gas Tungsten Arc Welding is used for thicknesses up to 3 mm (0.13 in). Although autogenous welding (without filler) could be used, no additional deoxidizers would be present, with the risk of producing porous welds. Direct current straight polarity, electrode negative (DCEN) is used for GTAW of most copper and copper alloys. Thoriated tungsten (usually EWTh-2) is preferred for its better performance, longer life, and greater resistance to contamination. This permits the use of an electrode that has a minimum diameter for a given welding current and that provides maximum penetration of the base material. Plasma arc welding (PAW) is preferred over GTAW, when available, because the tungsten electrode is concealed and shielded. This greatly reduces contamination, for alloys with low-boiling-temperature constituents such as brasses and bronzes, and it provides higher arc energies minimizing the Heat Affected Zone. PAW also permits the use of the 'Keyhole' technique, a rapid procedure suitable for welding thick joints. Gas Metal Arc Welding is preferred for section thicknesses above 3 mm (0.13 in.) and for the joining of aluminum bronzes, silicon bronzes, and copper-nickel alloys. Direct current reverse polarity, electrode positive (DCEP) is used for GMAW of copper alloys. Typically, argon is used as a shielding gas. Helium or a mixture of 75% helium and 25% argon is recommended for machine welding of thin sections and for manual welding of thicker sections of alloys that have high thermal conductivity. Although available for non demanding applications, the use of SMAW for Copper Alloys is not recommended because of reduced mechanical properties and possible unsoundness in the joints. In any case only the flat position should always be considered for SMAW. The covered electrodes used for Shielded Metal Arc Welding are designated as ECu. These are normally used with DCEP. Compared to carbon steel electrodes of the same diameter, the required welding current for ECu electrodes is typically 30 to 40% greater. Quality is generally lower and consumable costs may be higher than with alternative processes, but SMAW is sometimes selected, for low volume production, for its simplicity. Higher thermal conductivity and thermal expansion of copper and copper alloys result in greater weld distortion than in comparable steel welds. Copper-Zinc Filler Metals. Only low zinc containing filler metal should be used. These welding rods can be employed for braze welding of copper, bronze, and nickel alloys. Electrical conductivity is about 25% IACS; Thermal conductivity is about 30% of that of copper. Copper-Zinc Filler Metals of higher zinc content cannot be used as electrodes for the arc welding processes. The high zinc content tends to become volatile during arc welding and boils from the molten weld pool resulting in a porous weld. Phosphor bronze Copper-Tin welding electrodes and rods can be used with GTAW and PAW. They are designated as ECuSn-A, ERCuSn-A, (containing about 5% Sn, of lower strength) and ECuSn-C, (containing about 8% Sn, of higher strength). E indicates electrode for GMAW, R indicates Rod, but these prefixes are interchangeable if the usage is understood. Phosphorus is used as a deoxidizer for both electrodes. These are suitable for welding bronze, phosphor bronzes, brass, and copper if the presence of tin in the weld metal can be tolerated. They can be used for repair of castings, but preheat of about 200 oC (400 oF) is required for heavy sections. Silicon Bronze Copper-Silicon Filler Metals electrodes and rods, designated ERCuSi-A. are used bare for GMAW, GTAW, PAW, and also for oxyfuel welding. These are used for welding silicon bronzes and brasses and for braze welding of galvanized steel. The electrical conductivity and the thermal conductivity are low when compared to that of copper. For SMAW (not recommended as explained above) the covered electrodes in this filler metal classification are designated as ECuSi and are used for welding copper-zinc alloys and silicon bronze, copper, and galvanized steel with DCEP. Aluminum Bronze Copper-Aluminum Filler Metals are used mainly for hardfacing applications. ERCuAl-A is an aluminum bronze, used to provide wear resistance and mild corrosion resistance. A covered electrode called ECuAl-B, can be used for hardfacing and also for light repairs of aluminum bronze castings of similar composition. The covered electrodes for SMAW are designated as ECuAl-A2. The bare-wire electrodes for GTAW, GMAW, and PAW are designated as ERCuAl-A2. Both filler metals can be used for joining different kinds of bronzes and copper alloys. ERCuAl-A3 electrodes and rods are used for repair welding of aluminum bronze castings using GMAW and GTAW. The high aluminum content produces welds with less tendency to crack in highly stressed cross sections. Repair of wrought and cast aluminum bronze materials containing nickel can be performed with Copper-Nickel-Aluminum electrodes and bare wire designated ECuNiAl and ERCuNiAl. These materials offer good corrosion and cavitation resistance. Hardfacing and joining of Manganese-Nickel-Aluminum bronzes is performed with covered electrodes, designated as ECuMnNiAl, and bare filler metals, designated as ERCuMnNiAl. Like the Copper-Nickel-Aluminum electrodes, these electrodes have good resistance to cavitation, erosion, and corrosion. Copper-Nickel Filler Metals: covered electrodes for this classification are designated as ECuNi, and bare electrode wire and rods are designated as ERCuNi. These are used for the joining of Copper-Nickel alloys. A wealth of information on welding Copper-Nickel alloys can be retrieved
from Beryllium-Copper alloys are presented as High Conductivity (0.6% Be, Alloy 175) or as High Strength (1.7 or 1.9% Be, Alloys 170 and 172). A concern common to all types is keeping the surface free of beryllium and cuprous oxides. Alternating current, high frequency stabilized, helps break up the oxides. The first is more difficult to weld, exactly because of the higher conductivity. A hotter arc is obtained through the use of argon-helium mixtures. Best filler metal to be used is one of composition equal to the base metal (Alloy 175). For the other two alloys, again rods or strips of the same composition as the base metal are used, in preference to weaker standard copper alloys. -------------------------------------------------------------------------------------
5 - Online Press: recent Welding related Articles Experiences of a Weld Designer 85 years of Welding History On Pipe Welding see: Selecting a shielding gas for joining stainless steel The challenge of robotic welding Aluminum ------------------------------------------------------------------------------------- 6 - Terms and Definitions Reminder Lamellar Tearing is a dangerous planar defect occurring when certain plate materials presenting laminations are welded to a perpendicular element. Tearing occurs in the base metal plate adjacent to welds due to high shrinkage stresses in the thickness direction, introduced by weld metal shrinkage in highly restrained joints. Tearing takes place along laminations. These internal cracks usually run parallel to the weld. Laminations are a type of discontinuity with separation or weakness aligned parallel to the rolled surface of a metal. They are generally the result of defects internal to the material in bulk, flattened and elongated by rolling. Fitness for Service is a concept that allows individual flaws to be assessed and permits the operator to decide whether or not to repair. When a discontinuity is found in a weld, Fracture Mechanics analysis can be performed by computing the crack driving force (which is a function of the applied stresses, the flaw size, and the geometry) and comparing this with the resistance of the material to crack extension (which is the fracture toughness of the material in which the crack is found). Different approaches for calculating maximum acceptable flaw dimension according to Fitness for Service principles have been developed. They are formally presented in a number of Codes, some of which have been already widely used. Fracture Mechanics: a method of quantitative analysis for evaluating structural behavior (fracture instability) in terms of applied stress, crack size and shape, and specimen or structure component geometry. Impact Strength: a measure of the toughness of a solid. The maximum force or energy of a blow (given by a fixed procedure) that can be withstood without fracture, as opposed to fracture strength under a steadily increasing applied force. Spatter: the metal drops and particles expelled during arc or gas welding. They do not form part of the weld. Spatter loss is the metal lost due to spatter. Transition Temperature (of a given metal) is an arbitrarily defined temperature at which metal fracture characteristics (as usually determined by tests of notched specimens) change rapidly, such as the ductile- (above) to-brittle (below) transition temperature (DBTT). The DBTT can be assessed in several ways, i.e. the lowest temperature at which the fracture is 100% ductile (fibrous). Toughness is the ability of a material to absorb energy and deform plastically before fracturing. Toughness is proportional to the area under the stress-strain curve (of standard tensile test) from the origin to the breaking point. In metals, toughness is usually measured by the energy absorbed in a notched impact test. ------------------------------------------------------------------------------------- 7 - Article: Failures from weld discontinuities Note: The following refers essentially to arc welding. The performance of a weldment is determined in large part at the design stage, when the joint type has to be selected to make sure that it will transmit successfully the service stresses, provided that the inevitable imperfections introduced by practical application of welding processes are under control. But also the economy and the cost of manufacturing, including the weld size and the amount of filler metal to be deposited and the suitability of the process are decided on the drawing board. Joint design and weld details have a major effect on the fatigue life of structural elements. Therefore one must avoid discontinuities and stress raisers that can behave like cracks in weld details. The exact location and the magnitude of stress concentration in welded joints depend on the design of the joint and on the direction of the load. The list of common weld types includes: Butt, T, Corner, Lap and Edge. These may be further defined as Square, Bevel or special Groove, Fillet and finally Simple (if they are welded from one side only) or Double, from both. As pointed out in our Welding Advisers Site, any manufactured welded structure may be less than perfect due to some improper conditions. Click here for seeing the Site page on Welding Defects or imperfections. A local lack of physical material continuity appearing at or near the weld is called a discontinuity. Such a feature has to be detected, evaluated and decided upon: it may be considered a harmless imperfection or an intolerable defect to be removed, depending on the service the structure will sustain in operation. It should be observed that discontinuities, if present, should always be assessed: except that the techniques employed in practice need only be sensitive enough to detect harmful or rejectable indications. If more sensitive then required, a non destructive inspection technique is not an advantage. On the contrary it may be dangerous because the presence of too many irrelevant indications risks to mask those few but harmful ones that have to be evaluated and disposed of. Therefore a flaw or defect is nothing more than an excessive discontinuity, as determined by design acceptance/rejection requirements, based on past experience or on more modern criteria of Fitness for Service (click for definition, then close new window to come back) and calculated using the rules of Fracture Mechanics (click for definition, then close new window to come back). Discontinuities are commonly grouped according to some geometric characteristic. Cracks and planar discontinuities are the most dangerous, especially if fatigue loading conditions (i.e. successively increasing and decreasing) are present in service. Their shape extends mainly in two dimensions and constitutes stress raisers. In visual inspection only a linear indication may be visible. Different types of cracks are described. Usually none are tolerated (at the prescribed detection level), so that they must be removed by careful grinding (if superficial) or repaired by welding. The most insidious ones are those not open to the surface that may require specialized techniques to be detected and evaluated. Globular volumetric three dimensional discontinuities, porosity or inclusions, are usually found deep inside the weld. Porosity is a collective name describing cavities or pores caused by entrapment of gas in molten metal during solidification. Contaminants, moisture or inadequate shielding may stand at its origin. Hydrogen can diffuse in molten aluminum and is rejected upon solidification causing porosity. Relatively large bubbles or diffused clusters of small pores or pinholes, spherical or elongated can appear. Shrinkage voids can also shaw a similar aspect. The effects of porosity on performance depend upon quantity, size, alignment and orientation. When clustered at the center of a weld, they are not considered dangerous fatigue promoters, or highly detrimental to fatigue resistance, although they may reduce the static stress carrying capacity of the welded member. Inclusions are generated by extraneous material and disrupt the continuity of the base metal. They can be slag-, tungsten-, sulfide- or oxide-inclusions. Lack of complete fusion or incomplete penetration are internal planar discontinuities difficult to detect and evaluate but most dangerous especially if low Impact Strength (click for definition, then close new window to come back) and elevated Transition Temperature (click for definition, then close new window to come back) are determined for the material in cause and if cold weather may occur to promote low Toughness and brittle fracture (click for definition, then close new window to come back). Geometrical imperfections refer to those characteristic of the weld, like incorrect fit up, misalignment, and poor bead shape (undercut, underfill, overlap, melt through and distortion) as determined by visual inspection. They are an indication of inadequate workmanship and may be cause for concern if exceeding requirement limits. Craters are visually inspectable depressions indicating improper weld terminations, usually with the presence of radial cracks. They should be avoided or eliminated through improved welding skill or repaired if present. Spatter (click for definition, then close new window to come back), consisting in the presence of metal drops expelled from the weld, which stick to surrounding surfaces should be minimized by correcting the welding conditions and should be eliminated by grinding when present. Arc strikes appear as localized remelted metal from inadvertent or careless arc manipulation. They must be avoided and any traces removed because small cracks and their localized heat affected zone may become the origin of dangerous fatigue failures. Lamellar tearing (click for definition, then close new window to come back) is a dangerous planar defect that may occur when certain plate materials presenting Laminations (click for definition, then close new window to come back) are welded to a perpendicular element. Special joint design could be selected to minimize it, but the best precaution is to specify material of adequate quality. A number of different approaches for calculating maximum acceptable flow dimension according to Fitness for Service (click for definition, then close new window to come back) principles have been developed. They are formally presented in a number of Codes, some of which have been already widely used. ------------------------------------------------------------------------------------- 8 - Site Updating Increasing number and content of information items of our Welding Advisers Site is our primary commitment, to ensure that a useful and updated source is available for all readers as they come back to see what was added since last time. All articles published each month in Practical Welding Letter are later reported at the proper places in the Site pages, with direct links to be easily found. We believe they represent a valuable addition for interested readers. This time the Page of the Month subject is Flash Welding, a rapid mass production process useful for performing high quality butt welds to demanding items. It may be important to know advantages and limitations, to compare with competing processes that may be considered for manufacturing certain products. To reach that page click here. To write us your comments and needs, click here. ------------------------------------------------------------------------------------- 9 - Short Items 9.1 - Ion bombardment or ion implantation is a room temperature, plasma based surface improvement and modification technology that permits to change the surface properties of a material by implanting under vacuum selected gas ions impelled by electric energy. In tool steels the disturbance thus provoked provides hardness, reduces coefficient of friction, improves tribological properties, wear and corrosion resistance without disturbing dimensions or elevating the temperature. 9.2 - Industrial Computed Tomography is a non destructive radiographic technique that permits to obtain information on internal dimensions, shape, and defects, by helping drawing slices of the material body at any selected depths. Accurate positioning of internal features can also be identified. It may be used for research, for quality control or for reverse engineering. 9.3 - Isothermal Forging is a method of hot working of metallic blocks or billets, performed under vacuum or protective atmosphere, where there is minimal temperature difference between the dies and the metal. The deformations are performed at very slow strain rates, so that forged parts result with closer forging tolerances with minimum of internal stresses and free of forging defects. 9.4 - Molybdenum metal heating elements are used in vacuum furnaces for heating at temperatures up to 1900 oC. The molybdenum ribbons formed in heating elements must be shielded at all times from moisture and from oxidizing atmospheres. Upon heating and cooling they become very brittle and should be protected from mechanical and thermal shock. Molybdenum disilicide is a brittle ceramic material that can be formed in heating elements useful for heating furnaces in air and other gases at temperatures up to 1900 oC. 9.5 - Neutron radiography is a non destructive imaging technique that permits to put in evidence organic materials containing hydrogen even if buried deep into metallic bodies. Neutron radiography can image light materials that do not attenuate x-rays. The difference from regular x-ray or gamma ray radiography derives from the neutron absorption characteristics of materials, so that additional and complementary information becomes available. In particular it is used for controlling condition and position of organic propellants and explosives inside rocket engines. 9.6 - Rheocasting and Thixocasting are techniques exploiting the particular flow characteristics of certain light cast metals and alloys (mainly based on aluminum and/or magnesium), obtained when a semi-solid state is produced with viscous behavior and reduced shrinkage. In Rheocasting the molten liquid is vigorously stirred while cooling, maintaining in suspension the first solidifying crystals. In Thixocasting a solid billet is partially remelted. Flow is so enhanced that complex dies can be filled by gravity or under pressure, reproducing fine features with thin walls. Internal defects are minimized and quality is generally very good. ------------------------------------------------------------------------------------- 10 - Beyond the Welder Wolf restoration in Yellowstone Mission to Saturn Know your cicadas Space Junk A ridable scaled down Porsche ------------------------------------------------------------------------------------- 11 - Contributions 11.1 - Following the suggestion of a kind reader I have organized some internal links to Terms and Definitions: the interested reader, when so prompted, has to click on the term s/he needs explained, and the proper position in the Department will show up. To come back to the article being read, the new window has only to be closed. He suggested also to add an evaluation and interest voting form for each treated subject. I can tell you that a very important Magazine, (Advanced Material & Processes, issued by ASM International), which implemented such a voting feature, dropped it recently, I can guess why. I am ready to listen to readers' reactions to this proposal. Let us have your feedback. Click here. 11.2 - Another reader suggested to provide examples of mistakes that produced much harm in welding. While ready to publish such occurrences if they show up, we would like to stress that changing any of the parameters and conditions specified in any given Qualified Welding Procedure, will necessarily give bad results. Therefore there are unlimited occasions to wreck a good weld, and only a narrow range of conditions to do it well. This is the main reason that suggests that welding expertise (like any other) should be gained with time, study and effort. ------------------------------------------------------------------------------------- 12 - Testimonials From: "Mcadams, David W CIV" 'david.mcadams@navy.mil'
Thanks Elia! I really appreciate all the help! Dave McAdams ----------------
From: " [iso-8859-1] Thomas Bowley" 'lessmart2003@yahoo.co.uk' Elia, -------------------------------------------------------------------------------------
13 - Correspondence: A few comments 13.1 - A highly sophisticated reader, upon receiving the Hardness Book delivery that he had requested by subscription, asked me back to confirm that my message was indeed sent by a Human. Apart from the fact that his automatic link did not work, I would like to make it clear to everybody that I am not going to waste my time to accommodate unusual requests of sophisticated correspondents, to whom my regular e-mail routines seem not to meet their special needs. 13.2 - It happens that correspondents, out of thoughtlessness, ask me questions including mysterious initials or abbreviations that I fail to understand. (In one case there was an error, in another it was some proprietary product). Please show your respect by not adding needless work of interpretation when you present your questions. 13.3 - Once again I stress that corrispondents should be more creative in writing the subject on their messages, to convey the idea that indeed a welding subject is being dealt with. I continue to find 'no subject' or Hi or Help!. All these and similar definitions can cause the Delete button to be clicked upon without the messages being opened. You have been warned! -------------------------------------------------------------------------------------
14 - Bulletin Board 14.1 - Our Host, SiteSell.com, advised us of a dangerous situation developing in the Internet. This is due to errors, called "false positives", occurring in the filter programs intended to eliminate unsolicited and not wanted correspondence. Therefore, even innocent files can be canceled without being delivered to the recipients, however they might be interested and in need of them. We realize that this publication too might be occasionally a victim, although we take care to check every issue with an automatic program intended to establish the probability of any file being erroneously deleted by filters. This program can be used by anybody, by you too, see it at http://spamcheck.sitesell.com/Quark.html In case a subscriber finds out that this publication does not arrive, please let us know. For a more detailed explanation of the problem, of the danger and of possible solutions, see http://deliver-my-mail.sitesell.com/Quark.html 14.2 - The Seventh International Conference on Joining of Advanced and Specialty Materials will be held on Oct. 18-21 at the ASM International Materials Solutions Conference in Columbus, Ohio, USA. Visit http://www.asminternational.org/materialssolution/index.htm
Good Luck. See you next time. ------------------------------------------------------------------------------------- Copyright (c) 2004, by Elia E. Levi and welding-advisers.com, all rights reserved
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