8　Detecting the Underground Pipeline

8.1　General

8.1.1　The basic procedures and contents for underground pipeline detecting should meet the following requirements:

1　Gathering of information，site survey，and present investigation for underground pipeline.

2　Instrument inspection and method experiment.

3　Compilation of the technical design scheme.

4　Instrument detecting for underground pipeline.

5　Compilation of detecting sketch，data processing，and preparation of deliverables.

8.1.2　Before detecting the underground pipeline，the information of existing pipelines and topographic map in the survey area shall be comprehensively and systematically collected，analyzed and sorted，and the present investigation diagram for underground pipeline shall be prepared in combination with the site survey condition.

1　Pipeline information includes the design diagram，as-built diagram，exploration diagram，technical description and deliverables for all types of pipelines.

2　The topographic map includes the basic scale topographic map and relevant scale topographic map.

3　Based on sorting，classification and analysis of the information gathered，the present investigation diagram for underground pipeline shall be compiled according to the coordinates and sizes in pipeline design diagram，as-built diagram or detecting diagram，pipeline attribute data should be specified in present investigation diagram for underground pipeline，meanwhile the relevant underground pipeline present survey deliverables should be prepared whose contents include the attribute data and spatial data of pipeline feature points with the data source and evaluation accuracy specified.

4　The above ground pipeline or facilities connected to underground pipelines should be specified in present investigation diagram and present survey deliverables for underground pipeline.

8.1.3　The site survey shall be done based on gathering，sorting and analysis of the existing information，and should include the following:

1　Check of the gathered information，and evaluation of the reliability and usability of information.

2　Observation of the distribution and exposure condition of underground pipelines in the survey area.

3　Observation of the ground objects，physiognomy，transportation，geophysical conditions and all possible interference factors in the survey area.

4　Check of the position and preservation conditions of survey control points in the survey area.

8.1.4　After completion of site survey，proper detecting method shall be decided and necessary method experiment shall be done，on the basis of which the technical design scheme shall be compiled.The technical design scheme should include the following:

1　General condition of the detecting area，and the purpose，assignment，scope and requirement of the job.

2　Transportation conditions and relevant geophysical features，overview of the underground pipelines.

3　Effectiveness analysis of detecting method，work method and specific technical requirements and measures.

4　Work method and specific requirements for preparation of deliverables.

5　Operation quality assurance system and specific measures.

6　Existing problems and counter measures.

7　Estimation of work quantity and work schedule.

8　Manpower organization and contributory plan for instruments，equipment and materials.

9　Safety measures for pipeline detecting with regard to the features of petrochemical enterprises.

10　Deliverables and reports of detecting to be submitted.

8.1.5　The detecting of underground pipelines shall be based on gathering and analysis of the existing information and in combination of open-well investigation，instrument detecting，and shall track the underground pipeline by section and by line according to the connection conditions of above ground and underground pipelines.

8.1.6　For underground pipeline investigation and detecting，the laying of all types of underground pipelines shall be found out on site，and the surface marks for pipeline points shall be set up.The underground pipelines shall be positioned and with depth located，and the special data including projection position on the ground surface and burial depth of pipeline point shall be found out.Meanwhile，the attribute data including type，name，specification，material and medium feature and the connection relation between the underground pipeline and the above ground pipeline or facility shall be found out，which shall comply with the following the specifications:

1　The set-up of pipeline points shall be designed according to the specifications in Article 3.0.21 of this Code.

2　The detecting number of pipeline points should consist of pipeline code and pipeline point number.The codes of commonly used pipelines shall comply with the specifications in Table C.0.1 in Appendix C，and the codes of commonly used pipeline attachments shall comply with the specifications in Table C.0.2 in Appendix C，and the pipeline points shall be identified by numbers.The pipeline numbers shall be unique in the same survey area.If the client has numbered the distinct pipeline points including valve well，instrument well and fire hydrant，those numbers should be used and kept consistently.

3　For the distinct pipeline point，the exposed pipeline should be confirmed by open-well investigation，the attribute data of pipeline shall be investigated and the spatial data of pipeline shall be measured.

4　For the concealed pipeline points and underground pipeline，the connection condition of above ground and underground pipelines shall be considered，and geophysical detecting method and instrument detecting shall be taken，when necessary，the drill-rod detection and proofing hole（s）method may be taken to decide the attribute data and spatial data of pipeline.

5　Find out the source or starting point，flow direction，routing for pressure pipeline and cable/optical cable，and specify the results in underground pipeline investigation and detecting record sheet and underground pipeline detecting deliverables.

8.1.7　In investigation and detecting of underground pipeline，the spatial data including the routing，flow direction and connection relation of different types of pipelines and pipeline point numbers shall be marked in the relevant topographic map，and detecting sketch shall be prepared，and enlarged diagram（s）/crosssection profile（s）may be prepared on site with words description specified when necessary.The site investigation and detecting items for underground pipelines shall comply with the specifications in Table E.0.1 in Appendix E，and burial depth of pipeline shall be found out，and underground pipeline investigation and detecting record sheet shall be filled out and delivered for the application of underground pipeline survey procedures.The contents of underground pipeline investigation and detecting record sheet should be prepared according to the specifications in Table E.0.2 in Appendix E of this Code.

8.1.8　The detecting accuracy of underground pipeline shall meet the requirements in Article 3.0.22 of this Code.

8.1.9　The detecting for underground pipelines in the area of process units，utilities and storage &transportation facilities should continue until there are plant site utility pipelines or process pipelines around the BLs of the process units，utilities and storage & transportation facilities.

8.1.10　The detecting for underground pipelines on construction site shall be done in consideration of the requirements by the engineering，construction and client before the construction of dedicated project.The scope of detecting shall include the construction excavation area，the area where the safety of existing underground pipeline is likely to be impacted by excavation，and the area involved for finding out the existing underground pipeline.