Welding and joining plate, sheet and pipe. Richard E. Avery, Consultant to Nickel Development Institute; CDA Inc Seminar Technical Report 7. The Application of Copper Nickel Alloys in Marine Systems.- Joining Copper Nickel Alloys 1. Introduction. Cu- Ni alloys find many applications in marine, power, electrical and chemical industries. Blue Dots Consultancy with its well-established engagement models undertakes projects in Technical Writing, Localization, and Documentation Usability. Aristophanes’ breakthrough was to suggest that readers could annotate their documents, relieving the unbroken stream of text with dots of ink. The Legendary Pink Dots (LPD) are an Anglo-Dutch experimental rock band formed in London in August 1980. In 1984 the band moved to Amsterdam, playing with rotating. Typical hardware fabricated by welding are condenser and heat exchanger components, seawater piping, distillation apparatus and, demonstrating the excellent antifouling qualities of Alloy UNS C7. Copper Mariner. The composition of common Cu- Ni alloys and filler metals is shown in Table 1. Table 1. Composition of Cu- Nis. Composition, % maximum unless shown as a range or minimum. UNS Alloy No. Previous Trade Names. Cu. Ni. Pb. Fe. Zn. Home > Issue20 > Romero-Fresco article. Accessible filmmaking: Joining the dots between audiovisual translation, accessibility and filmmaking Pablo Romero-Fresco.Mn. Other Named Elements. C7. 04. 00. Cu- Ni, 5%Rem. C7. 06. 00. Cu- Ni, 1. Rem. 9. 0 - 1. 1. C7. 10. 00. Cu- Ni, 2. Rem. 1. 9. 0 - 2. C7. 15. 00. Cu- Ni, 3. Rem. 2. 9. 0 - 3. C7. 25. 00. Cu- Ni, Tin. Rem. 8. 5 - 1. 0. Sn. ERCu. Ni(a)(C7. Rem. 2. 9. 0 - 3. Si. 0. 2 P. 2 - . Ti. ECu. Ni(b)(W6. Rem. 2. 9. 0 - 3. Si. 0. 2 P. 5 Ti(a) ANSI/AWS 5. ANSI/AWS A5. 6- 8. Total of lead, zinc, tin and all other elements not named shall not exceed 0. Most alloys of Cu- Ni are solid solutions as shown in Figure 1. They may be work- hardened to tensile strengths above the 6. Ksi (4. 10 MPa) level. Typical annealed properties are of 1. Ksi (1. 00- 1. 40 MPa) yield strength and 4. Ksi (2. 75- 3. 50 MPa) tensile strength. Alloy C7. 19. 00 has alloying additions which enables it to be heat treated to a tensile strength of 8. Ksi (5. 50 MPa) and above. The Cu- Nis may be used in the work hardened condition as they are highly resistant to stress corrosion. Figure 1. Cu- Ni phase diagram. While copper and nickel are mutually soluble with each other as shown in Figure 1, a number of other elements are not soluble in the Cu- Ni alloy and if present may cause cracking in the heat affected zone (HAZ) or weld metal. Lead, sulfur and phosphorus are particularly detrimental and may cause intergranular hot cracking in highly restraint joints. Oil- or grease- base contaminants must be removed by solvent cleaning. Acceptable methods include immersion in, swabbing with or spraying with alkaline, emulsion, solvent or detergent cleaners or a combination of these; by vapor degreasing; by steam, with or without a cleaner; or by high- pressure water jetting. A typical procedure to remove oil or grease prior to welding includes: remove excess contamination by wiping with clean clothswab the weld area (at least 2 in. Use only clean solvents (uncontaminated with acid, alkali, oil or other foreign material) and clean clothsremove all solvent by wiping with clean, dry clothcheck to assure complete cleaning. A residue on the drying cloth can indicate incomplete cleaning. All the commonly used welding processes are applicable to the Cu- Ni alloys. A nominal 7. 0- 3. Cu- Ni filler metal with titanium as a deoxidizer is almost invariably used to weld all of the Cu- Ni alloys. Looking for Cheerleading Apparel or Cheerleading Clothes? We have just the Cheer Gear you are looking for! Come visit our site to find out more! WELCOME TO THE SAN FRANCISCO WORLD TRAVELERS (SFWT) We are a friendly group of like minded travelers who share a passion for visiting overseas destinations. A 9. 0- 1. 0 Cu- Ni bare filler metal and a covered electrode is available in Europe and occasionally used, but the bare wire is generally limited to gas tungsten arc welding (GTAW) gages up to 0. Welds made with 9. Cu- Ni fillers should be limited to non- wetting surfaces since the weld may be anodic to the base metal. Guides for the various welding processes follow. Back to Top. Shielded Metal Arc Welding. For shielded metal arc welding (SMAW), the flux covered electrode ECu. Ni is used with direct current electrode positive (reverse polarity). If the arc length is kept short, the weld pool can be controlled in all positions with a 3/3. Long arc lengths should be avoided because of the tendency to cause weld metal porosity. The electrodes should be operated within the manufacturer's recommended current ranges. Excessive amperages will result in weld spatter and undercut at the edge of the weld, especially when the base metal melting point is significantly below that of the filler. Weld defects are more likely to occur at arc starts and stops. In starting the arc, the proper technique is to strike the arc at some point in the joint so that the metal is remelted. In completing a pass, the arc should not be abruptly extinguished leaving a large weld crater. One acceptable technique is to hold the arc over the weld pool for a few moments and then move quickly back, lifting the arc from the completed weld. An open root gap and wide groove angle improves penetration and assures good fusion. Tack welds at least every six inches are needed to maintain the opening. A square- groove preparation for plate up to 1/4 in. The more common practice is to limit the square- groove to 1/8 in. For out- of- position welding, beveled grooves are required. The procedures presented in Table 2 were used for joining 1/4- in. The current settings shown may be useful as a guide in establishing parameters for other jobs. The proper setting will also depend on the nature of the duty cycle and power source. Both stringer and weaving techniques are successful with Cu- Ni alloys. However, weaving is usually necessary for vertical uphill and overhead position welding. Weaving should be limited to no more than three times the core wire diameter. Between passes, surfaces should be cleaned of flux by chipping and/or grinding. When backgouging in preparation for welding from the opposite side, it is essential to gouge to sound metal and to prepare a wide (8. Argon or mixtures of argon and helium at flow rates of 2. Spray transfer is generally used for 1/4- in. For welding sheet and plate from one side, grooved copper or Cu- Ni backing bars are preferred. Representative parameters used in joining Cu- Ni alloys by GMAW spray arc are shown in Table 3. Currents on the high side of the range are favored for the higher conductivity, lower nickel content alloys. Stringer beads and thin layers to minimize heat input are usually beneficial. Table 3. Representative Gas Metal- Arc Welding Properties. ECu. Ni filler, direct current, reverse polarity. Thickness(inches)Edge Preparation. Gap(in.)Voltage(volts)Current(amps)Wire Feed(in. ERCu. Ni contains 0. Ti, which serves as a deoxidizer to prevent porosity and oxygen embrittlement. Short circuit (GMAW- S) is a relatively low heat input process using 0. Argon shielding may be used, but argon- helium mixture gives better wetting and better bead contour. The low heat input allows welding in all positions. Pulsed arc (GMAW- P) incorporates many advantages of both spray arc and short circuit transfer and is well suited for welding C7. C7. 15. 00 alloys. The electrode diameter is usually 0. GMAW- P is adaptable to welding in all positions. A more recent advancement in pulsed welding is synergic or variable pulsed welding. With synergic welding, the welder has fewer welding variables to set and there is an improvement in weld quality. One observation often made when first GMA welding with ERCu. Ni filler metal is that the wire temper is noticeably lower than that of iron- or nickel- base fillers. Cu- Ni alloys do not work harden to nearly the same degree so the temper is usually lower. To minimize wire feeding difficulties, low friction cable liners should be used. Back to Top. Gas Tungsten Arc Welding. The GTAW process is the preferred process for welding thin gage material, 1/1. The all- position operability characteristic makes it an excellent process for pipe welding, particularly for small diameter pipe and the root pass of all pipe diameters. After a GTAW root pass in heavier pipe, the weld is often completed by GMAW or SMAW. Automatic GTAW equipment is available for applications such as tube to tube sheet welds, orbital pipe welding and joining sheet gages. Cu- Ni welds made without the addition of the deoxidized filler material very often have excessive porosity that is not apparent on the weld surface. For this reason autogenous GTA welds should be avoided. Other good welding practices to avoid porosity include a short arc, about 0. Argon is the usual shielding gas and preferred for purging the inside of pipes during root pass welding. Representative parameters for GTAW Cu- Nis are shown in Table 4. As with the other arc welding processes, the high conductivity, lower nickel alloys require currents on the high end of the range. Where possible, copper or Cu- Ni backing bars are favored. Table 4. Representative Gas Tungsten Arc Welding. ERCu. Ni filler, direct current, straight polarity. Thickness(in.)Electrode Size(in.)Filler Wire(in.)Current(amps)Argon Flow(cfh)1/1. Back to Top. Resistance Welding. Cu- Ni alloys with 1. Precautions must be taken to assure that surfaces to be resistance welded are clean and free from contaminants. Back to Top. Brazing. Cu- Ni alloys are most often brazed with silver- base brazing alloys. Fillers of AWS A5. Classifications BAg- 1a, BAg- 2, BAg- 1. BAg- 5 are ordinarily used. Alloys BCu. P- 5 and BCu. P- 3 are acceptable for use with Cu- Nis of 1. The corresponding UNS numbers are shown in Table 5. They should not be used for alloys with high nickel content due to the possibility that embrittling nickel phosphides will be formed. Copper- phosphorus brazing alloys should not be selected for service in sulfurous atmospheres. Table 5. Brazing Filler Metal UNS Numbers. AWS A5. 3 Classification. BAg- 1a. BAg- 1. BAg- 2. BAg- 5. BAg- 1. 8BCu. P- 3. BCu. P- 5. UNS Number. P0. 75. 00. P0. 74. P0. 73. 50. P0. 74. P0. 76. 00. C5. 52. C5. 52. 84. Fluxes of the AWS types FB3- A, C, E are satisfactory for most applications. For furnace brazing, inert gases, exogas, endogas or disassociated ammonia are suitable. The dew point should not exceed 2. For torch brazing, a neutral flame is used. Brazing clearances of 0. Also surfaces should be mechanically or chemically cleaned before brazing. Emery paper is usually satisfactory on pipe and tube. Solvents or alkaline cleaners should be used to remove grease and oil. An effective procedure for pickling to remove oxides is as follows: dip in 5% sulfuric acid at 1.
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