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发表于 2018-1-29 17:05:17
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本帖最后由 asnt2012 于 2018-1-29 19:50 编辑
石油天然气管道的无损检测比例如下：
API STD 1104 21ST Edition 2013 - 8.1 Rights of Inspection: The company shall have the right to inspect all weldsby nondestructive means or by removing welds and subjecting them to mechanicaltests. The inspection may be made during the welding or after the weld has beencompleted. The frequency of inspection shall be as specified by the company.
ASME B31.4 2016 - 434.8.5 Required Inspection and Acceptance Criteria
(a) Required Inspection
(1) The quality of welding shall be checked by visual inspection and supplemental nondestructive methods or by removing completed welds as selected and designated by the inspector for estructive testing.
(2) All welds shall be visually inspected.
(3) When the pipeline is to be operated at a hoop stress of more than 20% of the specified minimum yield strength of the pipe, the welds shall be inspected. A minimum of 10% of the girth welds and 10% of the other welds completed each day shall be randomly selected by the operating company and nondestructively inspected. The inspection of girth welds shall be by radiographic or other accepted volumetric methods. Nonvolumetric methods, such as dye penetrant or magnetic particle, may be used for other welds. Each weld inspected shall be inspected completely with the selected method. In the following locations or conditions, all welds in the pipe shall be completely inspected; however, if some of the welds are inaccessible, a minimum of 90% of the welds are to be inspected:
(-a) within populated areas such as residential subdivisions, shopping centers, and designated commercial and industrial areas
(-b) river, lake, and stream crossings within the area subject to frequent inundation; and river, lake, and stream crossings on bridges
(-c) railroad or public highway rights-of-way, including tunnels, bridges, and overhead railroad and road crossings
(-d) offshore and inland coastal waters
(-e) old girth welds in used pipe
(-f) tie-in girth welds not hydrostatically tested in accordance with para. 437.4.1
ASME B31.8 2016 - 826 WELD INSPECTION REQUIREMENTS
826.1 Visual Inspection
Visual inspection of welds must be conducted by a person qualified by appropriate training and experience.
826.2 Inspection of Welds on Piping Systems Intended to Operate at Hoop Stress Levels of Less Than 20% of the Specified Minimum Yield Strength
The quality of welds shall be checked visually on a sampling basis, and defective welds shall be repaired or removed from the line.
826.3 Inspection and Tests for Quality Control of Welds on Piping Systems Intended to Operate at Hoop Stress Levels of 20% or More of the Specified Minimum Yield Strength
(a) The quality of each weld shall be examined by visual inspection.
(b) In addition, a certain percentage of the welds shall be examined through radiographic examination, ultrasonic testing, magnetic particle testing, or other comparable and acceptable methods of nondestructive testing. The trepanning method of nondestructive testing is prohibited.
The following minimum number of field butt welds shall be selected on a random basis by the operating company from each day’s construction for examination. Each weld so selected shall be examined over its entire circumference or else the equivalent length of welds shall be examined if the operating company chooses to examine only a part of the circumference of each. The same minimum percentages shall be examined for double ending at railhead or yard.
(1) 10% of welds in Location Class 1.
(2) 15% of welds in Location Class 2.
(3) 40% of welds in Location Class 3.
(4) 75% of welds in Location Class 4.
(5) 100% of the welds in compressor stations, and at major or navigable river crossings, major highway crossings, and railroad crossings, if practical, but in no case less than 90%. All tie-in welds not subjected to a pressure proof test shall be examined.
(c) All welds that are inspected must either meet the standards of acceptability of API 1104 or be appropriately repaired and reinspected. The results of the inspection shall be used to control the quality of welds.
(d) When radiographic examination is employed, a procedure meeting the requirements of API 1104 shall be followed.
(e) When pipe size is less than NPS 6 (DN 150), or when the construction project involves such a limited number of welds that nondestructive inspection would be impractical, and the pipe is intended to operate at hoop stress levels of 40% or less of the specified minimum yield strength, then provisions (b) and (c) above are not mandatory, provided the welds are inspected visually and approved by a qualified welding inspector.
(f) In addition to the nondestructive inspection requirements outlined above, the quality of welds shall be continually controlled by qualified personnel.
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