Nondestructive Testing service providers

  Material testing Mechanical testing  have been designed to test several weld properties.Few other material testing techniques are Charpy V-Notch Toughness: Notch toughness is the capacity that a material possesses to  absorb energy  in the  presence of a flaw , such as a notch or crack. The material will likely exhibit a lower level of toughness. When a flaw is present in a material, loading induces a triaxial tension stres s state adjacent to the flaw. The material  develops plastic strains  as the yield stress is exceeded, near the crack tip. Notch-toughness is  measured with a variety of specimens  such as the  Charpy V-notch impact  specimen or the dynamic tear test specimen. As with regular impact testing the tests are often repeated numerous times with specimens tested at a different temperature. With these specimens and by varying the loading speed and the temperature, it is possible to  generate curves such as those s...

  Bend Test Coupon Preparation First the centerline on the plate shall be marked. Then another line  1.0 inch  above the center line  and another line 1 inch below the center line. This is the section that can be used as an  alternate coupon  in the event of  corner cracks  with no evidence of slag inclusions. Next, marking of the actual  root  and face bend specimens. Using the top and bottom line, another line a minimum of  1½ inches above.   The top line shall be marked and then  1½ inches below  the bottom line. The  minimum width  of a test specimen needs to be  1½ inches  wide. After that the  Welding Inspector shall mark the weld test coupons  for a root and face bend in agreement with the welder, cutting them on a band saw. Backing Bar Removal: The  backing bar  removal can be done using a vice and using a grinder on the center of the backing bar to gouge it, about ...

  Most field welding machines are portable, that is, they are on a truck and can be moved around. The welding equipment is usually a generator driven by a gasoline-powered engine and puts a DC current that may be reversed by changing the leads. The  welding machine  must contain a gauge or some means of determining the amperage output along with some method of increasing or decreasing the amperage as desired. The leads shall be in good condition with cleaned connections at both ends. Good quality electrodes are a must. Welding manufacturers produce good quality electrodes that conform to the AWS test requirements, however, this does not ensure their good quality when delivered to the job site. The welder should discard any damaged electrodes. When using low hydrogen electrodes, he/she must furnish them from undamaged hermetically-sealed containers and have an oven for maintaining their dryness. The welder’s cleaning tools should consist of a chipping hammer and a wire bru...

  WELDING INSPECTOR KNOWLEDGES: The Welding Inspector must be a high skilled technician or engineer with a good knowledge of general industry manufacture, materials, quality systems, inspection procedures and Standards and Specifications for welding as:   Standard organizations as ASTM, SAE, AISI, AWS, ASME and other institutions; Metals metallurgy, hardness tests and heat treatment; Materials properties, destructive testing and NDT methods; Terminology, weld joint geometry and welding symbols; Welding equipment, metal joining and cutting processes; Application of procedures, records, welding inspection and qualifications; Evaluation of weld and base metal discontinuities; Metric and conversion practices; Safe welding practices; 1.  Standards and Specifications for welding:   The professional and industrial organizations in the United States that lead the development of standards include: the ASTM International, the Society of Automotive Engineers (SAE), the American...

  The procedure requirements for welding electrodes and preheating temperatures are as follows: Welding must be done with the same process (SMAW or FCAW) used for qualification If the operator has qualified on any of the steel permitted (ASTM A36 and A588), that same operator is qualified to weld on the other and on SAE 1010 or ASTM. A welder qualified for manual shielded metal-arc welding with an  E7018  electrodes may also weld with  E7016 electrodes .Identifying electrode numbers are as follows:  a. The  70 designation  shall be understood to mean the  70 series  unless an alloy steel of higher strength is to be welded. b. The third digit indicates the position permitted. If the  digit is “1,”  the electrode may be used for welding in any position. If “2,” only the down hand position may be used. c. The  fourth digit  indicates the chemical make-up of the electrode coating. The  digit 6  indicates  low hy...

  Welding of Stainless Steels: General Concepts: Stainless steels, resumed here in a general way, are defined as steel alloys, where the  chromium content  ranges from  10.5% to 30%.  There are five distinct types of stainless steel: Ferritic stainless steel: Contains from  10.5 to 30% chromium , is low in carbon, with some alloys containing major amounts of molybdenum, columbium and titanium. Austenitic stainless steel: Contains from  16% to 26% chromium  and up to 35% nickel and have very low carbon content. Some of these steels are also alloyed with a minor amount of molybdenum, columbium and titanium. Martensitic alloy steel: Contains from  12% to 17% chromium  and up to 4% nickel and 0.1% to 1.0% carbon. Some alloys will also have minor additions of molybdenum, vanadium, columbium, aluminum and copper. Duplex stainless alloys: Contain  18% to 28% chromium , 2.5% to 7.5% nickel and low carbon contents. Some of the alloys will al...