IT-TRANSIT | Diagnosis and evaluation of the technical state of the linearly extended objects

Diagnosis and evaluation of the technical state of the linearly extended objects

The main objective of the pipeline and transport sector production is to control the safe operation of the main and auxiliary equipment of the transport system. To ensure stable operation of the pipeline and transport system must be timely execution of procedural, maintenance and diagnostic measures, rapid response to emergencies and timely obtaining th information about the objects, their condition and estimated terms of safe operation.

The system of technical condition assessment of the linear objects is intended for storage and process of results of the conducted surveys and diagnostics on linear part of main gas pipeline (LP MGP) objects, calculation and analysis of the technical condition of pipeline on the basis of a complex of diagnostic, maintenance, spatial and technical data used in the enterprise standards, to determine the safe operation terms of the pipeline, make recommendations on the impact of interventions to ensure reliable operation of the LP MGP equipment and performance of transportation plans.

For providing these purposes the following developed modules are used:

Automated import of the diagnostics results

For the technical condition assessment of the main pipelines objects the existence of various sources information is an important condition for carrying out the comprehensive analysis of data on objects and an exception of possible uncertainty in their assessment.

For analysis and additional comprehensive estimation, all the diagnostic examination results should be entered to the database. This procedure may be performed in a manual mode or in a controlled import mode.

The system has a block of program modules for automated import to the diagnostic database, including:

PIG-inspection (PIGI) data,
results of comprehensive detailed electrometry (DE),
seasonal Test station (TS) measurements,
operation modes of Cathodic protection station,
control pitting data,
data on MGP underwater crossings inspection, data on road and railway crossing inspections,
results of wall thickness test, vibrometry, geodetic control and other works aimed to determine the pipeline condition.

To accomplish the import package for each block of diagnostic data, universal exchange formats were developed based on either MS Excel or XML files. Diagnostic data may be preliminary processed manually by a work executor, and must correspond to the developed format of import with the determined data set which will be used in the procedures of identification by the system, processing, linking and calculation.

Diagnostic data are imported to the system with the algorithms of their spatial coding, which allows to bring all diagnostic measurements to actual linear distances (operating mileage) of the pipelines and to correlate both with each other and with the system passport data. Spatial linkage is performed in several ways: by reference objects, by the pipe logs previously entered, by identical pipeline facilities etc. Moreover, a user is able to analyze correctness of spatial linkage, to modify the linkage method, to suspend import and to adjust the input data at all times.

Furthermore, the system has also the function of geodetic data import for spatial description of the pipeline and its bedding depth, which are primarily input into the system for a new section or renovated while monitoring of the existing pipeline location. Geodetic data are imported to the system, compared and linked to the key process facilities and reference points, whereupon they may be used as basic in estimation analytical models.

Revealed defect risk assessment

Dangerousness of defects revealed during the diagnostic inspections is assessed with a special functional, which relies on the valid standards for determination of the defects dangerousness level, terms of their inspection, repairs and recommended removal methods. The system performs calculations according to the main international standards:

DNV-RP-F101 (Norway)
ASME B31G-1991 (USA)
RSTRENG (USA)
STO Gazprom 2007-2009 (Russia)
VBN (Ukraine).

Simultaneous application of several standards during the assessment of defect hazard allows to describe technical condition of the pipeline in the most precise way.

Results of the selected defect estimation are displayed in geometrical and data electronic form, contain information about assessed dangerousness of the defects according to various standards, as well as the information about basic destructive factors in the defect location (closest to the defect data on pressure, temperature and stress are displayed).

In case of repeated identification, comparison and confirmation of the defect, its development may be traced in the defect e-form, localized on the map and displayed on the pipeline section.

Predictive modeling of defects

The system provides a possibility to analyze and modelling the hazard of single defect, and to modify its properties.

Through the change of basic parameters featured by the selected defect, among which: value of its length, width and depth, properties of the pipe metal, ultimate stress, yield point and other parameters, it is possible to analyze the defect acceptance limits in case of its development.

It is also possible to modelling a situation with the changed mode of gas transportation for the set defect parameters.

With the function of single defect calculation, it is possible to determine the admissible factor of safety, safe pressure, pre-response time, safe pressure coefficient with regard to the selected defect.

Сomparative analysis of data obtained by nonsimultaneous PIG inspections

In order to monitor the pipeline condition during repeated PIG inspectionsins the calculation and analytical systems use a special function enabling to conduct a comparative analysis of data obtained from multi diagnostic tests, and to display defects in graphical form.

The function of PIGI data comparison allows to analyse the data obtained from two non-simeltaneous PIG-inspections with possibility to evaluate of defect size changing over time.

Evaluation of the transportation safe mode

During risk assessment of revealed pipeline defects a part of them is qualified as dangerous and unacceptable that demands immediate intervention and implementation of rescue and recovery operations on the pipeline. With the technical or organizational and financial impossibility to perform repair work in full elimination of unacceptable defects and restore the integrity of the pipeline only way to avoid an emergency situation is to change the modes of transport and thus decrease the load on the pipeline.

The specialized module of gas transportation safe mode calculations allows to execute calculation of the admissible mode of transportation at which pressure decrease in the pipeline will provide downgrade of unacceptable defects to "conditionally inadmissible" or even "admissible". The module allows to count the permissible modes of transportation with a task of accurate amount of the defects demanding immediate repair that allows to unite dispatching problems of transportation with concrete financial and material opportunities of repair divisions of the enterprise.

This module can also make calculation towards the planned increasing in productivity of the pipeline with controlled load increase on it and an assessment of defects amount that need to be repaired thus for maintaining the integrity of the pipeline and ensuring its reliability. Results of calculating the amount of the repaired pipes will be displayed on the repair card of MGP site, with possibility to print, save to PDF, display a list of the repaired pipes.

Appointment of the optimum methods of repair

The functionality which in the automatic mode make purpose of an optimum way of repair for all defects of the set pipeline site, to calculate necessary quantity of a repair pipe and to make a preliminary estimate of cost of rescue and recovery operations is developed for planning and an assessment of volumes of repair work at detection of pipes metal defects.

The method of repair work for the revealed defect automatically calculated after import in GIS DB of PIGI data on the basis of the Russian standard RD 558-97 of JSC Gazprom which establishes the main requirements to the pipes and technology of welding choice, and also criteria of rejection of pipes and welded connections.

All information about the repair work is entered in the repair form and recorded in the system. As a result of repairs, the system automatically updates the information about the executed works and removal of defects, which allows to overestimate the technical condition of the pipeline and perform analysis of the restoration of its integrity.

The repair scheme on a pipeline site and repair map on each pipe, containing the dangerous defect planned to eliminate, is formed. The main technological objects (valves), the repaired numbed pipes, a statistic legend of repairs are localized on the scheme. The scheme of repairs can be printed or kept in the PDF format.

Information on a pipe is displayed when loading pipe repair map: its number, distance in kilometers and geographical coordinates for the navigation purposes of field search, orient markers and distance to them, sizes and location of defects. Is possible to pass to chosen on the repair map defect's detailed passport.

Defects on pipe repair map is differentiated by colors on a depth or danger degree, according to the chosen standard and the mode of transportation.

Repair planning

Module 'Repair planning' is implemented to optimize repair actions planning process, unite resources regarding management of repairs purpose. automatic formation of the List of the pipes, sorted as elimination of defects by danger decrease is formed automatically. For those pipes on which calculation of safe pressure isn't carried out, there's a choice of repairs priority according to the enterprise requirements .

The module allows to appoint a repair site (PIG inspection selected section), to automatically generate the pipe list to repair, sorted by priority in a descending order of danger on the basis of calculations carried out earlier. After that the expert makes division of the pipe list which are subject to repair into stages by two criteria:

achievement of repair planned volumes (selectable number of repaired pipes);
achievement of required safety parameters (safe mode of transportation selected as a result of repair gets out).

The module allows to choose the standard to which the safe pressure is calculated for comparison with the current pressure on the site:

ASME B31.G mod (USA) ;
DNV-RP-F101 (Norvay);
RSTRENG (USA).

The module performs site repair map generating with the displaying of pipes, pipes numbers and repair method, as well as statistics on the number of repair types and eliminated defects.

Comprehensive analysis of the pipeline technical condition

Comprehensive analysis of the pipeline technical condition can be carried out using a fixed set of thematic charts, selected in particular combinations and sequences in the following areas:

Evaluation of insulation - determines the quality of the insulation coating in pipeline selected area;
Corrosion situation - describes the degree of corrosion hazard MT;
The analysis of Catodical Protection Station (CPS) operational effectiveness - displays the level of pipeline protection at different operating modes of CPS;
Estimating of failure probability - displays reliability level assessment on pipeline sites.

Comparison and analysis of thematic data complex, output of the results in the form of single line diagrams is carried out on the basis of the same name module. These solutions contain a specified set of diagrams in the prescribed manner and allow to make spatial analysis of pipeline condition by increasing or decreasing display linear scale, by changing the charts display order, by using the tool of transition to passport technical information of objects, by analyzing indicators at the cursor position.

Using the module "Single line diagram" tools you can add and compose additional single-line diagrams for the unlimited number of different pipeline characteristics analysis that are stored in the database, for the following values:

situation – describes situation along the pipeline;
pipeline – describes location and marks of technological objects along the MGP;
cathodic protection objects – describes location and reference marks of cathodic protection objects;
pipe log– describes the distribution of pipeline by welds;
metal defects – describes revealed defects by PIG inspection results;
profile – describes the pipeline ground position (in axial presentation);
TS seasonal measurements – describes the results of measurements of the potentials on the MGP;
detailed electrometric measurements – describes the results of electrometric measurements along the MGP;
corrosion situation – describes the degree of corrosion danger of MGP on the basis of soil resistivity;
soil resistivity – describes the sections of the pipeline are located in areas of high corrosion danger (HCD) and low corrosion danger (LCD).

Field Pitting recorder

The developed module «Mobile Pitting» enables interactive work with diagnostic data. The application allows you to work independently in field, to perform input results during pitting, compare and edit the parameters of defects and to perform a preliminary assessment of their danger, and perform:

view of the pitting acts list;
creation of a new pitting act;
binding pitting act to the pipeline;
interactive editing of the passports and synchronize with the database.

Field defects analyzer

The developed module performs calculations on your mobile device by entering the parameters of the detected defects, provides the ability to work interactively with diagnostic data. The application allows you to perform autonomously:

calculation of defects danger by standards: ASME, DNV, RSTRENG, Gazprom, VBN;
displaying of defects on the tube;
editing parameters of defects;
editing of the metal pipe characteristics ;
grouping and combining of the defects according to DNV;
risk assessment of the defect.