Welding standards

There is one documented report that a welder had good intentions when he decided that the welding standard for the roof-to-wall seam was inadequate. This well-meaning welder added a full strength weld to join the roof to the walls. [2] There were no reported problems on this tank, but the safety feature was rendered ineffective. 

Design allowables on ultimate tensile strength 0.25 in. 7075-T73 plate friction stir weld standard pin tool AMP03005-2... 

Samples of type 301 stainless steel were obtained which had been cold-worked 42, 62, and 78. The chemical analyses of these steels are given in Table I. The chemistry was normal for AISI type 301, except that carbon was held to a maximum of 0.10 to minimize carbide precipitation during welding. Standard sheet specimens were prepared for tensile tests, while notched sheet specimens were used to determine notch tensile strength. A notch-acuity factor of about 6.3 was... 

It is particularly in the serial inspection of castings, that radioscopy constitutes state-of-the-art when applied in conjunction with systems for image intensification, digital image processing and automatic image evaluation. For the examination of welds, however, standardization is still non-existent, thus rendering more difficult the application of this inspection technique.As a consequence the approval procedures of the respective supervisory or certification boards are often complicated and of necessity set up for each individual case. 

Since a standard is so far non-existent, the full utilization of the advantages in radioscopy is not possible. In particular for the inspection of welds this sometimes will lead to costly individual approval procedures by the supervisory institutions. 

GOST 23055-78. Russian standard. "Classification of welded joints by results of radiography testing and corresponding production forms and records". 

The first stage in any inspection is to generate a proeedure which is specific to the component being examined in many instances, such a procedure will be based on a standard such as CEN J5I/-EN1714 Non-Destructive Testing of Welds - Ultrasonic Examination of Welded Joints . CamuS incorporates a tool ProcGen to provide assistance with this task. 

For produetion eontrol of small diameter nozzle welds a magnetic wheel scarmer has been build (Figure 4). One standard motor module drives the magnetic wheel and one standard motor module drives the Y-module slide. The two motors are connected to the Master Module. The scanner is controlled from a FORCE Institute PSP-3 ultrasonic acquisition unit with build-in scarmer controller. 

Application of Surface SH Wave s Detection Standard for the Ultrasonic Inspection of Weld Defects in Steel Structures, 3rd Revision, Architectural Institute of Japan, P27, (1996)... 

Two main types of harmonised standards can be distinguished the product standards and the horizontal standards. The latter, as their denomination indicates, contain issues of a horizontal nature, e.g. for materials or provisions relating to welding or welder approvals. These standards should be formulated in such a way as to be self-sufficient. That means it should be possible to apply them without having to use individual product standards. 

After many decades of application, industry has completely accepted standard NDT as an inevitable but invaluable part of production and maintenance of components. Its application has been well-regulated, acceptance criteria for weld defects exist, good schemes for personnel qualification are in place and equipment has evolved to a standard of nearperfection. NDT has become a commodity. Pioneering years are over. 

NDT has a very important formal status. Requirements for performanee of NDT, acceptance criteria and requirements for personnel qualification are implemented in codes and standards. The NDT procedure is part of the contract. During the many years that NDT methods have been used in industry a well-established situation has evolved, enabling the use of NDT for the evaluation of welds against Good Workmanship Criteria on a routine basis, thus maintaining workmanship standards and minimising the risks of component failure. 

For many years, the technical capabilities of standard NDT methods did not allow for this approach. If NDT would have produced quantitative data on defect size from the beginning, it is highly probable that current acceptance criteria for weld defects would have used this information. Acceptance criteria would have been completely different from what they are... 

Standard commercial iastmmentation and control devices are used ia fluorine systems. Pressure is measured usiag Bourdon-type gauges or pressure transducers. Stainless steel or Monel constmction is recommended for parts ia contact with fluoriae. Standard thermocouples are used for all fluorine temperature-measuriag equipment, such as the stainless-steel shielded type, iaserted through a threaded compression fitting welded iato the line. For high temperature service, nickel-shielded thermocouples should be used. 

Welding American Welding Society P.O. Box 351040 550 NWLeJeune Road Miami, Fla. 33135 Codes, Standards and Specifications, 2l comf[.e.X.e... 

In 1962, the first method for welding (qv) metals ia spots along a linear path by explosive detonation was patented (8). This method is not, however, used iadustriaHy. In 1963, a theory that explained how and why cladding occurs was pubHshed (9). Research efforts resulted ia process patents which standardized iadustrial explosion cladding. Several of the patents describe the use of variables iavolved ia parallel cladding which is the most popular form of explosion cladding (10—13). Several excellent reviews on metal cladding have been pubHshed (14—16). 

Destructive Testing. Destmctive testing is used to determine the strength of the weld and the effect of the explosion-welding process on the parent metals. Standard testing techniques can be utilized on many composites however, nonstandard or specially designed tests often are required to provide meaningful data for specific appHcations. 

Hot Work. The objective of a hot work standard is to prevent fires, explosions, and other causes of injury which might result from workplace ignition sources such as welding (qv), cutting, grinding, and use of electrically powered tools. The OSHA standards have specific requirements (36,94) for fire prevention and protection and a permit system. 

Ak ammonia piping should be standard (Schedule 40) or extra heavy (Schedule 80) steel having welded or screwed joints, respectively. Galvanized piping or brazed joints should never be used. Ammonia accepted for pipeline transportation must meet the fokowing specifications NH, 99.5 vol % min dissolved inerts, 0.16% max, ok, 5 ppm max and water, in the form of steam condensate, 0.2% min, or distiked water, 0.5% max. 

Included ia the OSHA regulations are standards for safe work practices such as lock-out/tag-out and confined space entry, personal protective equipment, storage of hazardous materials, welding process, forklift operation, and requirements for fire protection. Basically, all activities within a chemical facihty are covered by OSHA standards. 

American National Standard Z49.1, Safety in Welding and Cutting AWS PubHcations, American Welding Society, Miami, Fla., 1994. 

Tank Shell. Another example of where thickness is set by minimums for fabricabihty but not for strength is in small-diameter tanks. For example, a water storage tank built using a steel of an allowable stress of 20,000 psi (138 mPa), 9 ft (3 m) in diameter by 21-ft (7-m) high, requires a shell thickness to resist hoop stress of only 0.023-in. (0.58-mm) thick. However, if built to API Standard 650, the shell would be fabricated at least 0.1875-in. (4.76-mm) thick. The code requires this thickness so that when fabrication, welding, and tolerances are considered, a tank of acceptable quaUty and appearance meeting the requirements of most services in most locations is provided. 

Operations capable of generating airborne beryUium particulate, such as melting, machining, welding, grinding, etc, are effectively controUed by local exhaust ventilation or other control measures. To assure a safe environment and measure compliance with the OSHA standards, employee exposures should be periodicaUy measured by prescribed air sampling and analytical methods. 

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