A discontinuity is not necessarily a defect. Solidification cracks can appear in several locations, and orientations, but most commonly are longitudinal centreline cracks coincident with the intersection of grains growing from opposite sides of the weld , or 'flare' cracks, again longitudinal, but at an angle to the through-thickness direction Fig.
Where there is a central segregate band in the plate, cracking may extend from this position at the fusion boundary Fig. The cracks in all locations can be buried Fig. Inspector: An individual who is qualified and certified to perform inspections under the proper inspection code or who holds a valid and current National Board Commission. These evaluations or tests may provide either qualitative or quantitative information that is sufficient to verify the nominal alloy composition.
All reportable indications are recordable indications but not vice-versa. This dimension is based on the assumption that the root opening is equal to zero. Welding inspection includes much more than just the non- destructive examination of the completed weld. Many other issues are important, such as review of specifications, joint design, cleaning procedures, and welding procedures.
Welder qualifications should be performed to better assure the weldment performs properly in service. Welding inspection activities can be separated into three stages corresponding to the welding work process.
Many welding problems can be avoided during this stage when it is easier to make changes and corrections, rather than after the welding is in progress or completed. Such tasks may include: 4. Welding symbols and weld sizes clearly specified See Appendix A. Weld joint designs and dimensions clearly specified see Appendix A. Weld maps identify the welding procedure specification WPS to be used for specific weld joints.
Dimensions detailed and potential for distortion addressed. Welding consumables specified see 7. Proper handling of consumables, if any, identified see 7.
Base material requirements specified such as the use of impact tested materials where notch ductility is a requirement in low temperature service. Mechanical properties and required testing identified see Weather protection and wind break requirements defined. Preheat requirements and acceptable preheat methods defined see Inspection hold-points and NDE requirements defined see Section 9.
Additional requirements, such as production weld coupons, clearly specified. Pressure testing requirements, if any, clearly specified see 9. Identify and clarify missing details and information. Identify and clarify missing weld sizes, dimensions, tests, and any additional requirements. Identify and clarify inconsistencies with standards, codes and specification requirements.
Highlight potential weld problems not addressed in the design. Review requirements for the weldment with the personnel involved with executing the work such as the design engineer, welding engineer, welding organization and inspection organization. Competency of welding organization to perform welding activities in accordance with codes, standards, and specifications.
Competency of inspection organization to perform specified inspection tasks. Roles and responsibilities of engineers, welding organization, and welding inspectors defined and appropriate for the work. Independence of the inspection organization from the production organization is clear and demonstrated. WPS s are properly qualified and meet applicable codes, standards and specifications for the work see 6. Qualify WPS s where required and witness qualification effort.
Qualify or re-qualify welders where required and witness a percentage of the welder qualifications. NDE procedures are current and accurate. Calibration of NDE equipment is current. Identify and correct deficiencies in certifications and procedures. Obtain calibrated equipment.
Welding machine calibration is current b. Instruments such as ammeters, voltmeters, contact pyrometers, have current calibrations. Storage ovens for welding consumables operate with automatic heat control and visible temperature indication. Recalibrate equipment and instruments. Replace defective equipment and instruments. Active, Most Current Currently Viewing. Browse Publishers.
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Related Books Free with a 30 day trial from Scribd. Uncommon Carriers John McPhee. The Art of War Sun Tsu. Related Audiobooks Free with a 30 day trial from Scribd. Elizabeth Howell. All rights reserved to thePetroStreet team Minimum Ferrite Number for filler metal should be 4 FN except for the following: — The minimum FN for type shall be 5 FN — When joining stainless steels for cryogenic service, non-magnetic applications, or special corrosive service, consumables with a lower FN may be required.
The maximum ferrite number for E weld deposits shall be 5 FN When austenitic stainless steel weld materials are used at service temperatures above C: — Materials shall have a formulation that does not intentionally add bismuth, and bismuth in the deposited weld metal shall not exceed 0. Ferrite content shall be measured on base metal, HAZ and weld metal. The preheat temperature shall be applied throughout the entire thickness of the weld and at least 4 in. The preheat and interpass temperature shall be checked by use of thermocouples temperature indicating crayonsThe preheat and interpass temperature shall be checked by use of thermocouples, temperature indicating crayons, pyrometers or other suitable methods.
The maximum interpass temperature shall be specified in the WPS and PQR for austenitic stainless steels, duplex stainless steels, and non-ferrous alloys and, when impact testing is required for carbon and low-alloy steels.
When welding high carbon equivalent forgings and fittings, special welding procedures including preheat and cooling rate control for hardness management needs to be developed to reduce risk of Hydrogen Assisted Cracking.
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