Pipeline flaw detection is an ultrasonic method for inspecting pipes, welds and joints. Flaw detection Flaw detection of pipelines

Real estate 26.09.2020

Real estate

The aging of pipelines in continuous operation for more than 20 years is:

oil pipelines - 60%,
gas pipelines - 40%.

The main goal that he sets for himself pipeline diagnostics, is the detection of corrosion. Solving this problem will ensure trouble-free operation and increase service life. In addition, diagnostic tasks include reducing the cost of energy delivery and saving it.

Diagnostics includes acoustic, magnetometric, optoelectronic techniques. To carry them out, special equipment is used.

These methods are designed to prevent the occurrence emergency situations through early detection of damage sites that precede the development of corrosion. The devices allow you to indicate not only the location of possible destruction, but also its type.

Introduction to widespread diagnostic practice serves to increase the reliability and economic efficiency objects of gas and oil transport organizations, as well as housing and communal services enterprises.

Pipeline transport and non-destructive testing

Several principles of control are applied to pipeline transport facilities. The main attention is paid to equipment and equipment operating under difficult conditions of high pressure, temperature changes and others. Pipelines are typical objects of non-destructive testing, the methods and equipment of which are well established, and the necessary equipment can be purchased or rented without delay.

Ultrasonic flaw detection of large castings for pipeline transport

Most often used for pipe inspection ultrasonic non-destructive testing, For the implementation of which many devices and devices have been developed and produced. If necessary, it is possible to use the X-ray method and other methods, because in testing of this kind it is not the fact of control that is important, but its practical result.

In addition to pipelines, this type of transport has several more typical objects that require monitoring, for example, pumping stations, gas storage equipment, tanks, liquefied gas production plants and much more.

An important stage has come in the constant quality control of pipelines with the start of operation of special equipment capable of performing many control operations inside pipes, including checking the quality of metal and weld, basic geometric indicators and other data.

Research and production laboratory "PROcontrol" provides a range of services for multi-parameter technical diagnostics cold/hot water supply pipelines.

We carry out comprehensive diagnostics using ultrasonic and magnetic methods, according to the pipeline inspection methodology of JSC MOEK. Based on the inspection results, areas of defects are identified.

An ultrasonic inspection system uses special grids, called rings, that wrap around the pipe being tested. The ring transmits a series of directed ultrasonic waves and receives the reflected signals. The condition of the pipeline, “possible defects” in the form of corrosion and/or a decrease in the thickness of the wall section are determined by reflections from places where the area changes cross section pipes. The results of processing echo signals are displayed in the form of a graph, where the distance from the ring is displayed on the abscissa axis, and in the form of an hourly sweep.

Our laboratory conducts research into the possibility of identifying corroded sections of the pipeline on specialized stands with standard defects.

Defects in the base metal of pipes and welded joints test bench: zone of pitting corrosion (a), accumulation of crack-like defects in the base metal of the pipe (b), crack-like defect in the longitudinal weld (c).

Flaw detection should be carried out using one of the non-destructive testing methods (radiographic, ultrasonic, acoustic emission, magnetic particle, capillary) in cases where the specialists performing the inspection have doubts about the quality of the metal or welded joint of a particular pipeline element.

In addition, it is necessary to selectively monitor at least two joints on two or three pipelines of one installation of each steel grade, operating at temperatures above 450 0 C for carbon steels and above 500 0 C for alloy steels.

The choice of the flaw detection method, the assignment of the scope and inspection locations are carried out by the specialists performing the inspection. In this case, the chosen non-destructive testing method should most fully identify defects and their boundaries.

Scope of control welded joints must correspond to the values given in Table 19.

Table 19 - Scope of control of welded joints by ultrasonic or radiographic method in % of the total number of joints welded by each welder (but not less than one)

*Note.

Operational control includes:

a) checking the quality and compliance of pipes and welding materials with the requirements of standards and technical specifications for production and delivery;

b) checking the quality of preparation of the ends of pipes and pipeline parts for welding and the quality of assembly of joints (bevel angle of edges, coincidence of edges, gap in the joint before welding, correct alignment of pipes, location and number of tacks, absence of cracks in tacks);

c) checking the preheating temperature;

d) checking the quality and technology of welding (welding mode, order of seams, quality of layer-by-layer stripping of slag);

e) checking the heat treatment conditions of welded joints.

Also subject to control:

Repaired sections of the pipeline (in the absence of repair documentation) - 100%;

Welded joints from dissimilar steels – 100%.

If, during inspection, areas of the pipeline surface with cracks or cracks in welded joints are detected, the defective areas should be removed, and similar areas should be selectively subjected to flaw detection. If the results of flaw detection are unsatisfactory, the specialists performing the examination must make a decision on additional volume flaw detection control.

Ultrasonic testing of welded joints must be carried out in accordance with GOST 14782-76 “Non-destructive testing. Welded connections. Ultrasonic methods” in accordance with industry standards or instructions developed by specialized organizations.

Acoustic emission control is carried out in accordance with PB 03-593-03 “Rules for organizing and conducting acoustic emission control of vessels, apparatus, boilers and process pipelines.”

Radiographic testing of welded joints must be carried out in accordance with GOST 7512-82 “Non-destructive testing. Welded connections. Radiographic Method,” radiography instructions or industry standards.

Flaw detection methods

The most common and popular pipeline flaw detection methods include:

Magnetic particle testing. The essence of the technique is based on recording stray magnetic fields that appear above defects. By their nature, you can determine the size, location and depth of damage. Magnetic particle testing uses ferromagnetic mixtures and powders. They are able to identify surface and internal cracks, delaminations, sunsets and other defects that are not located deeply.
Radiographic flaw detection. The technique is based on the ability of X-ray radiation to penetrate metal and be fixed on the surface of a special film. Rays penetrating through damage leave a mark on it. Radiographic examinations can detect lack of fusion, cracks, pores, foreign bodies and undercuts.
Acoustic emission quality control of pipelines. This type The research is based on the recording and analysis of sound waves that appear due to the growth of cracks and deformations of the object being assessed. Acoustic emission flaw detection allows you to detect even developing defects.
Ultrasonic flaw detection. This quality control technique is based on the ability of ultrasonic waves to reflect from various surfaces. This makes it possible to identify internal and subtle external defects. Ultrasonic flaw detection is different high accuracy and efficiency of execution.
Capillary studies. This flaw detection method is based on capillary penetration of indicator liquids into the material and recording the results. During capillary quality control, through and surface defects, their extent and location are detected. The results of the study are very clear.
Magnetometric diagnostics. Based on measurements of the magnetic permeability of pipe walls. The technique makes it possible to detect a decrease in their thickness that occurs under the influence of corrosion and during long-term operation. Such studies are carried out to prevent accidents.

This is far from full list studies conducted for quality control purposes. Flaw detection techniques are selected individually in each case. They can also be combined with each other. This allows you to obtain the most reliable results.

In accordance with SNiP 3.05.03-85, the contractor carries out ultrasonic flaw detection of pipeline joints during the construction of a category IV heating route. Quality control costs welds determined according to the prices of the GESNm-2001 Collection No. 39 “Inspection of installation welded joints”.

There were disagreements with the customer regarding the source of financing. The customer believes that compensation for these costs should take place through overhead costs under the article “Costs for the maintenance of production laboratories - payment for services provided to laboratories by other organizations (Appendix 6, section III, paragraph 9).

Is the Customer right?

Answer:

The customer is wrong, since there is an additional clarification from Rosstroy on this issue, which states that if non-destructive testing of welded joints is carried out by specialized organizations, then these costs are included in Chapter 9 of the consolidated estimate as a separate line in columns 7 and 8 and are paid to these organizations on the basis of the submitted accounts with the conclusion of an agreement.

Letter from Rosstroy dated January 28, 2005. No. 6-35 is given below. IN " Guidelines to determine the amount of overhead costs in construction", appendix 6, section III, clause 9 "Costs for the maintenance of production laboratories" it is indicated that the overhead cost standards provide for the costs of paying for services provided to laboratories by other organizations.

The clarification of this provision is due to the fact that when these Guidelines were being prepared, Rosstroy believed that budgetary organizations will provide services free of charge. However, in fact, budgetary service organizations created private intermediaries and Rosstroy was forced to clarify this issue. It must be borne in mind that if there are discrepancies in the current documents on any issue, one should be guided by the document that was most recently published (Rosstroy’s letter No. 6-99 dated February 25, 2005 is given below).

Federal agency on construction and housing and communal services reports on the issue raised. In cases where ultrasonic testing and other types of non-destructive testing of welded joints are carried out by contractors construction organizations, the costs of their implementation are included in the overhead costs of contractors and are compensated by overhead costs accrued in the estimate documentation and acceptance certificates for work performed when the customer pays for the work to the contractor.

In cases where ultrasonic testing and other types of non-destructive testing of welded joints are carried out by specialized organizations, the costs of organizing testing of welded joints using non-destructive methods performed by specialized organizations are included in Chapter 9 of the consolidated estimate calculation as a separate line in gr. 7 and 8 and are paid to specialized organizations on the basis of submitted invoices with the conclusion of an agreement to perform work on monitoring welded joints using non-destructive methods.

The same applies to concrete testing using non-destructive methods.

The costs of stamp testing of soils are included in the overhead costs of contractors. The costs of geodetic control over the construction of buildings and structures and their structural elements, including channel supports, are included in the overhead costs of contractors. The costs of developing work projects, including the technological regulations for performing these works, are included in the overhead costs of contractors.

Letter from the Federal Agency for Construction and Housing and Communal Services

The Federal Agency for Construction and Housing and Communal Services reports on this issue.

With approval of the Methodology for determining the cost of construction products on the territory Russian Federation- , The Code of Rules for determining the cost of construction as part of pre-design and design estimates documentation - SP 81-09-94 - has lost force.

Regarding the determination of the amount of funds, one should be guided by the above-mentioned Methodology and the Collection of estimated cost standards for the construction of temporary buildings and structures -.

If there are discrepancies in the current documents on any issue, the most recently published document should be used.

Head of the Construction Department R.A. Maksakov