Active Edition from 09.10.1996

DESIGN AND CONSTRUCTION OF GAS PIPELINES FROM POLYETHYLENE PIPES WITH A DIAMETER OF UP TO 300 MM. SP 42-101-96

9. INPUT INSPECTION OF PIPES AND CONNECTING PARTS

9.1. Each batch of pipes and fittings must be provided with a document (certificate) from the manufacturer (or a copy certified by the owner of the certificate) confirming their compliance with the requirements of the technical specifications. The certificate must contain the name and trademark of the enterprise, batch number, symbol products, batch volume (m, pcs, kg), test results or confirmation of compliance with the requirements of the standard or TU, batch release date.

The surface of pipes and fittings must be marked (see clause 3.7).

9.2. Upon receipt of a batch of pipes at construction sites, it is necessary to carry out an incoming quality control of pipes and fittings, the purpose of which is to determine the suitability of this batch for the construction of gas pipelines. Pipes must be fastened in packages or in bays.

9.3. The input control should consist of determining: the appearance of the surface and the dimensions of pipes and parts. If there is any doubt about the quality of the materials received at the construction site polyethylene pipes it is recommended to additionally carry out selective testing of samples with the determination of the value, tensile yield strength and relative elongation at break. Mechanical tests must be carried out by laboratories of construction and installation organizations or under contracts with testing centers.

9.4. For incoming inspection, a certain percentage is selected depending on the diameter:

d_e 225 mm - 2% of pipes or fittings from the batch

d_e 160 and 110 mm - 1% - "-

d_e 63 and 40 mm - 0.5% - "-

d_e 32 and 20 mm - 0.25% - "-

The number of pipes in any case must be at least 5 pcs.

When using pipes in coils for incoming inspection, it is necessary to provide a piece of pipe with a length of at least 2 m, sufficient for the manufacture of at least 25 samples.

9.5. By appearance pipes must have a smooth outer and inner surface. Insignificant longitudinal stripes and waviness are allowed, not leading the wall thickness beyond the limits of permissible deviations (Appendix 6); bubbles, as well as other individual defects in accordance with GOST 24105 with a depth of more than 0.7 mm, are not allowed on the surface and at the ends of the pipes.

9.6. The inner and outer surfaces of the connecting parts must not have cracks, swellings, burns, shells, inclusions and other damage. Minor marks from the forming tool, traces of machining and cold joints, protrusions from remote sprues on the connecting surfaces are not more than 0.5 mm, and on other surfaces - not more than 3 mm.

9.7. The appearance of the surface of pipes and parts is determined visually without the use of magnifying instruments. The depth of defects is determined using a dial indicator with a division value of 0.01 mm.

9.8. The dimensions of pipes and parts (diameters, wall thicknesses) are determined at a temperature of (23 ± 5) ° С. Before measurement, the samples are kept at the specified temperature for at least 2 hours.

Measurement of the outer diameter d_e of pipes is carried out on five samples in three sections of each sample at a distance of at least 150 mm from the ends.

Measurement of the outer diameter of the connecting ends of the parts is carried out at each end of at least five parts at a distance of 5 mm from the ends.

For pipes and parts with a diameter of 160 mm or less, the value d_e is determined as the arithmetic mean of measurements of the maximum and minimum diameters in two mutually perpendicular directions in one section. Measurements are carried out with a caliper GOST 166430 or a micrometer GOST 7507-78 types MT and MK with an error of 0.1 mm.

For pipes and parts with a diameter of more than 160 mm, the value of d_e is calculated by the formula:

where: P - perimeter (mm), measured with a tape measure GOST 7502-80 with an error of 0.5 mm;

T is the thickness of the tape measure (mm), measured with a micrometer with an error of 0.01 mm.

9.9. The wall thickness is measured with an indicator wall gauge GOST 11951, or a micrometer of the MT GOST 6507-78 type with an error of up to 0.01 mm at four points evenly distributed around the circumference:

for pipes - from both ends of each pipe at a distance of 10 mm from the end (at least 5 pipes);

For parts - at each connecting end at least five parts at a distance of 5 mm from the end (at least 5 parts).

9.10. The calculated average values ​​of de and each of the wall thickness measurements should not go beyond the permissible deviations regulated by the relevant specifications for pipes and fittings.

9.11. Tensile yield strength (delta_rt) and elongation at break (E_pp) are determined for pipe material according to GOST 11262-80 on samples from the corresponding number of samples taken according to clause 9.4.

For pipes supplied according to TU 6-19-352-87 and TU 6-49-04719662-120-94, tests are carried out on sample blades of type 1 GOST 11262-80, with a nominal pipe wall thickness of up to 6 mm, and type 2 , with a nominal wall thickness of pipes over 6 mm.

For pipes supplied in accordance with GOST R 50838-95, tests are carried out on sample blades of type 2 GOST 11262-80.

For pipes with an outer diameter of up to 20 mm, tests can be carried out on samples in the form of a pipe segment 160 ± 5 mm long. To fix the sample in the testing machine, clamps of the appropriate shape are used, and plugs 30 mm long made of an elastic material (for example, rubber) are inserted into the sample from both ends to prevent their crushing.

The thickness of the sample blade is assumed to be equal to the thickness of the pipe wall (without eliminating the curvature of the surface).

For the manufacture of sample blades, pipes 160 + 5 mm long are cut off from pipes selected for testing, from which they are cut out with a punch-cut or samples are cut out by machining (milling) so that their longitudinal axis is parallel to the generatrix of the pipe. With a pipe wall thickness of more than 10 mm, sample blades are made only by mechanical processing.

Tests are carried out at a temperature of 23 ± 2 ° C on tensile machines, for example, type 2054-R5, 2099-R5, IR5047-50 and others, providing load measurement with an error of not more than 1% of the measured value.

The speed of movement of clamps, tensile testing machine when testing pipes supplied according to TU 6-19-352-87 is 50 ± 5.0 mm/min for samples with a nominal wall thickness of less than 6 mm and 25 ± 2.0 mm/min - for samples with a nominal wall thickness of 6 mm or more.

For pipes supplied in accordance with GOST R 50838-95 and TU 6-49-04719662-120-94, the speed is 100 ± 10.0 mm/min for samples with a nominal wall thickness of up to 10 mm and 25 ± 2.0 mm / min for samples with a nominal wall thickness of 10 mm or more.

9.12. The test result should be taken as:

arithmetic mean value of the yield strength and minimum value relative elongation - for pipes supplied according to TU 6-19-352-87;

The minimum values ​​of the yield strength and relative elongation are for pipes supplied in accordance with GOST R 50838-95 and TU 6-49-04719662-120-94.

Tensile yield strength must be at least 15 MPa (152 kgf/cm2) for pipes made of PE 80 (PSP) according to TU 6-49-04719662-120-94 and at least 19 MPa (193 kgf/cm2) for pipes made of PE 63 (HDPE) according to TU 6-19-352-87. The relative elongation for the specified pipe materials must be at least 350%.

9.13. If unsatisfactory results are obtained for at least one of the indicators (appearance, dimensions and mechanical properties), this indicator is re-controlled on a double number of samples taken from the same batch. In case of secondary unsatisfactory results, control tests are carried out in the presence of a representative of the manufacturer of this batch of pipes (parts).

9.14. According to the results of the input control, a protocol is drawn up (the recommended form of the protocol is given in Appendix 16), which is part of the documentation presented to the acceptance committee when the facility is put into operation.

9.15. If the warranty period for the storage of pipes or fittings, specified in the technical specifications, has expired, then a conclusion on the suitability of pipes or fittings for the construction of gas pipelines can be issued either by the manufacturer or by a testing laboratory accredited by the Gosstandart of Russia, after a set of tests regulated by the technical conditions on pipes or parts.

9.16. The input control of pipes and fittings of foreign delivery is also carried out according to clause 9.4, taking into account the requirements of the technical specifications for the supply.

7.1 Pipe products supplied to construction sites are subject to incoming control, carried out in two stages, providing for survey and rejection (for pipe products subject to technical supervision in accordance with RD-03.100.50-KTN-122-13).

7.2 The first stage of incoming control is carried out by the customer's representative during the unloading of products at the destination. By the decision of the customer, the first stage of incoming control is carried out jointly with a representative of the customer's construction control. The involvement of specialists from the building control body of the customer at the first stage of incoming control is carried out on a separate application.

7.3 During the implementation of the first stage of input control, the following is performed:

Checking incoming products for compliance technical requirements, working documentation, quality certificates (or declarations of conformity);

Checking the presence of markings according to requirements normative documents, as well as their compliance with the data specified in the passports and certificates;

Verification of serial numbers of products with technical supervision data for products that have been accepted by the customer’s technical supervision representative at the manufacturing plant and shipped to the customer’s address (only for supervised products supplied by third-party organizations (not OST) that repack MT during work (not included to the OST Development Program) for the reconstruction railway tracks, roads and other communications, and having direct contracts with Transneft Nadzor LLC for construction control and technical supervision services);

Checking the availability of originals (or duly certified copies) of passports and certificates (or declarations of conformity) certifying the compliance of products with the specifications for delivery;

Checking the presence in passports and certificates (or declarations of conformity) of a mark on the acceptance of products by the technical supervision of the customer at the manufacturer's plant;

Inspection of products for shipping damage.

7.4 Based on the results of the first stage of the input control, an input control report is drawn up in the form of Appendix A OR-03.100.50-KTN-120-10. If a decision is made on non-conformity of products, claim work is carried out in accordance with contractual obligations.

7.5 The second stage of control is carried out on a commission basis with the participation of representatives of the work foreman, the quality control service of the contracting organization, the Customer and the Customer’s construction control and in accordance with the input control flow sheets that are part of the agreed and approved WEP, after unloading at the construction site (storage site) from using means of instrumental control. The results of the second stage of the input control of the MTR are drawn up by the Act in the form 3.3 VSN 012-88.

7.6 When performing work on the incoming inspection of connecting parts and stop valves, as well as at the second stage of incoming inspection of tubular products, the following is carried out:

1) survey of pipes and pipeline parts:

For the absence of unacceptable mechanical damage, metallurgical defects and corrosion, including delaminations that go to the edge and surface of products, nicks, scratches, dents on the body and on the ends;

On the value of deviations of the pipe diameter and wall thickness from the nominal dimensions;

For the compliance of the deviations of the chamfer angle, the oblique cut of the ends, the ovality of the ends, the curvature of the pipes and the removal of the reinforcement of the internal seam with the requirements of the current norms and rules;

The thickness of the pipe wall and the thickness of the factory insulation;

To the width of the uninsulated part of the pipe edge;

The angle of cutting the edges of the pipe and factory insulation;

For the availability of accompanying documentation and the completeness of the data provided in it; the presence of the technical specifications of the manufacturer of the products and the compliance of the supplied materials with these technical specifications;

For the presence of marking and its compliance with passport data and the manufacturer's specifications;

For the absence of unacceptable surface defects in welds;

2) control over the repair of pipes with permissible surface defects, according to a technology that meets the requirements of the current rules and regulations, with the execution of acts of the established form;

3) control of the state of shut-off valves (gate valves), check valves, safety and control valves, pumping equipment;

4) control of the correct storage of pipes, pipeline parts, fittings and equipment;

5) checking the availability of originals (or duly certified copies) of certificates (or declarations of conformity) and passports, their compliance with incoming materials, products and equipment (including compliance with the equivalent carbon content design solutions);

6) measurement parameters:

Pipe ends, parts (diameter, ovality, wall thickness, dents);

Outer diameter of the body of pipes, parts;

Deviations of wall thickness at the ends;

Pipe edge parameters, details;

pipe curvature;

Kosina cut ends of pipes, parts;

The quality of the surface and welds of pipes;

Ultrasonic thickness measurement of pipe walls;

7) Bending quality control:

Checking the absence of defects in the stretched part of the seam;

Control of places of deformations of cold bend bends

Checking the ovality of the ends of the bends and the curved part

7.7 Methods and scope of control.

1) Visual and measuring control:

Visual 100% of all pipes, fittings and valves,

Instrumental in the amount of 5% selectively, plus products (pipes, parts), ultrasonic pipe wall thickness measurement in the amount of 5% selectively, if one pipe with unacceptable parameters is detected - 100% control of the entire batch of pipes.

2) For pipes with a factory insulating coating, the following is additionally carried out:

Continuity control of the factory insulating coating (continuity check - 5% of pipes, if a defect is detected, the scope of the check is doubled, if a defect is detected again - the entire batch is rejected);

Measurement of the thickness of the insulating coating (electromagnetic (magnetic) thickness measurement of the insulating coating in the amount of 5% selectively, upon detection of one pipe with unacceptable coating parameters in appearance - 100% batch control).

3) For pipes with factory thermal insulation coating additionally carried out:

Control of the thickness of the thermal insulation coating;

Control of the integrity of the thermal insulation coating.

7.8 Timing of the SC.

7.8.1 The performer of the work shall, in time sufficient for the mobilization of the SC specialists, but not less than 1 day in advance, notify the deadlines for completing the work and presenting them for examination. Notification of the IC body about the need to conduct control measures for the acceptance of work performed, if it is necessary to present work that requires specialized control and measuring equipment, it is carried out within 3 working days.

7.8.2 Deadlines for carrying out routine maintenance for the implementation of construction control during the incoming inspection of pipes, valves, shaped products, equipment and materials during the construction of the linear part of the MN and MNPP should be calculated based on the volume of construction and installation work performed, taking into account 100% visual and 5% instrumental control, but should not exceed 1 working day after the work is submitted for control / examination by the construction contractor.

7.8.3 Completeness control executive documentation carried out by the SC personnel on a daily basis upon completion of the relevant work at the facility.

7.8.4 Routine work on the implementation of construction control during the incoming inspection of pipes, valves, fittings, equipment and materials during the construction of the linear part of MN and MNPP are given in Table 2.

Table 2 - Routine work on the implementation of construction control during the input control of pipes, valves, fittings, equipment and materials.

8 The procedure for the implementation of construction control during the input control of insulating and warmly insulating materials, pipeline surface preparation and application of insulating and heat-insulating coating

8.1 During the input control of insulating materials, the following is checked:

Compliance of heat-shrinkable cuffs with the requirements of the project, the manufacturer's specifications, other norms and rules; completeness and warranty period

Conformity physical properties epoxy primer (primer) to the requirements of norms and rules;

Compliance of storage of insulating materials with the requirements of norms and rules;

Compliance of the gas used to heat the insulated joints with the requirements of the working documentation for the composition and climatic modification;

Compliance of hoses and burners used for heating insulated joints with the requirements of normative and technical documentation and technical design.

8.2 During the input control of heat-insulating materials, the following is checked:

Compliance of heat-insulating materials and products with project requirements.

Conformity couplings project requirements, integrity, geometric dimensions.

8.3 Methods and scope of control.

8.3.1 Visual and measuring control:

1) selective inspection of polymer tapes, heat-shrink sleeves and other insulating materials in warehouses - 5% of the total volume, selective quality control of heat-shrink sleeves and tapes:

Inspection (quality and condition of the adhesive layer, absence of through damage, integrity of the couplings),

Instrumentally (width, thickness of the tape, adhesion to the primed steel surface and overlapping)* – 1 sample from a lot, but not less than 1 sample from 50 rolls

2) selectively checking the quality of the primer (glue, primer):

Inspection (homogeneity), package integrity, marking, expiration date

Instrumental - density[*], viscosity*, dry residue*, adhesion* - 1 sample from a batch.

8.4 Timing of the SC.

8.4.1 The performer of the works shall notify within a time sufficient for the mobilization of the SC specialists, but not less than 1 day in advance, of the deadlines for completing the works and presenting them for examination. Notification of the IC body of the need to carry out control measures for the acceptance of work performed, if it is necessary to present works that require specialized control and measuring equipment, is made 3 working days in advance.

8.4.2 The timing of routine maintenance for the implementation of construction control during the input control of insulating and heat-insulating materials, preparing the surface of the pipeline and applying insulating and heat-insulating coatings during the construction of the linear part of the MN and MNPP should be calculated based on the volume of construction and installation work performed, taking into account 100% visual and 5% of instrumental control, but should not exceed 1 working day after the work is submitted for control/survey by the construction contractor.

8.4.3 The control of the completeness of execution of the as-built documentation is carried out by the personnel of the IC on a daily basis upon the completion of the relevant work at the facility with a note in the construction control log of the customer and the contractor.

8.4.4 Routine work on the implementation of construction control during the input control of insulating and heat-insulating materials, preparing the surface of the pipeline and applying insulating and heat-insulating coatings during the construction of the linear part of MN and MNPP are given in Table 3.

Note

Table 3 - Routine work on the implementation of construction control during the input control of insulating and heat-insulating materials, preparing the surface of the pipeline and applying insulating and heat-insulating
coatings

GUIDANCE DOCUMENT

the dateintroductions 01.07.91

This guidance document establishes a method for manual input ultrasonic testing (UT) of the metal quality of cold-worked, heat-worked and hot-worked seamless pipes made of carbon, alloy and austenitic steels used for the manufacture of chemical, oil and gas equipment.

The guidance document applies to pipes with a diameter of 57 mm or more with a wall thickness of 3.5 mm or more.

It is allowed to use mechanized ultrasonic testing of pipe metal according to the instructions developed by specialized technological organizations.

The guidance document was developed in accordance with the requirements of the Rules for the Design and safe operation pressure vessels”, GOST 17410, OST 26-291, technological instructions TI 101-8-68, OST 108.885.01.

1. GENERAL PROVISIONS

1.1. Ultrasonic testing is carried out in order to identify internal and external defects of pipes such as shells, cracks, sunsets, delaminations, captivity and others without deciphering the type, shape and nature of the detected defects, indicating their number, depth and conditional dimensions.

1.2. The need for ultrasonic testing of pipe metal at consumers is established in the following cases:

When supplying pipes that have not been subjected to hydraulic testing and (or) replacement of tests for control by physical methods in accordance with the instructions of clause 3.9 of the Rules for the Design and Safe Operation of Pressure Vessels and clause 2.3.9 of OST 26-291;

When using pipes manufactured according to technical requirements without the use of non-destructive methods control, in order to assess the continuity of the metal and pipe sorting, taking into account the requirements of TU 14-3-460 and other documentation that provides for ultrasonic testing, and their subsequent application, for example, for steam pipelines and hot water;

With the introduction of incoming ultrasonic testing of pipes at the consumer plant by decision of the design or technological department.

1.4. Ultrasonic testing is carried out after the elimination of unacceptable defects found during visual testing.

1.5. The inspection does not guarantee the detection of defects in the end sections of the pipe at a length equal to half the width (diameter) of the working surface of the transducer.

1.6. Control documentation containing deviations from the requirements of this guidance document or incorporating new control methods should be consistent with specialized organizations industries (NIIkhimmash, VNIIPTkhimnefteapparatura, etc.).

2. EQUIPMENT

2.1. Flaw detectors and transducers

2.1.1. When testing pipe metal, ultrasonic pulsed flaw detectors of types UD2-12, UD-11PU, DUK-66PM or others that meet the requirements of this guideline should be used. To control pipes for delamination, it is allowed to use ultrasonic thickness gauges of the Quartz-6 type or others.

2.1.2. Thickness gauges and flaw detectors once a year, as well as after each repair, are subject to mandatory state or departmental verification. During verification, visual inspection and determination of specifications appliances in accordance with guidelines according to verification and requirements of GOST 23667.

The dead zone should be no more than:

8 mm - for inclined transducers with an input angle of 38° and 50° for a frequency of 2.5 MHz;

3 mm - for inclined transducers with an input angle of 38° and 50° for a frequency of 5 MHz and PC transducers for frequencies of 2.5 and 5 MHz.

Instead of surface treatment, the use of stabilizing supports and nozzles is allowed (see).

3.3.4. The ultrasonic testing laboratory should have:

Ultrasonic flaw detectors with sets of typical transducers, standard and test samples;

AC supply with a frequency of 50 Hz and a voltage of 220 (127) and 36 V;

Chargers type AZU-0.4 or others;

Voltage stabilizer for mains voltage fluctuations exceeding plus 5 or minus 10% of the nominal value;

Reel with portable network cable;

Ground bus;

A set of metalwork and measuring tools;

Contact medium and cleaning material;

Work tables;

Racks and cabinets for storing equipment and materials.

3.4. Surface preparation under control

3.4.1. Pipes must be cleaned of dust, abrasive powder, dirt, oils, paint, flaking scale and other surface contaminants and numbered. Sharp edges at the end of the pipe must not have burrs.

3.4.2. On the outer surfaces of the pipes there should be no dents, nicks, traces of cutting, leakage, splashes of molten metal and other surface irregularities.

In the case of mechanical processing, the surface must have a roughness Rz ≤ 40 - according to GOST 2789.

3.4.3. Quality control of surface preparation should be checked by employees of the technical control service. It is recommended to prepare surface cleaning samples.

The pipes are presented to the flaw inspector fully prepared for inspection.

3.4.4. To ensure acoustic contact between the surfaces of the transducer and the product, it is recommended to use the contact media specified in the reference.

It is also allowed to use technical vaseline, machine oil, technical glycerin with their subsequent removal from the surface of the pipes.

At elevated temperatures or a large curvature of the surface of the controlled pipes, a contact medium of a thicker consistency should be used. At low temperatures, it is recommended to use car oils or transformer oil.

3.5. Selection of inspection parameters and flaw detector setup

3.5.1. The choice of control parameters depends on the outer diameter of the pipe and the wall thickness. The parameters of ultrasonic testing are:

Exit point and transducer boom;

The angle of entry of the ultrasonic beam;

Working frequency;

Ultimate sensitivity;

sounding method;

Speed, scan step.

The main parameters of ultrasonic testing of pipe metal are given in the table.

Optionsultrasoniccontrol

3.5.2. The exit point of the ultrasonic beam and the transducer boom are determined according to the standard sample CO-3 - according to GOST 14782.

3.5.3. The angle of entry of the ultrasonic beam is measured using the CO-2 standard sample scale - according to GOST 14782. For transducers with an acoustic axis tilt angle of 30° and 40°, the input angle should be 38 ± 2° and 50 ± 2°, respectively.

3.5.4. To ensure acoustic contact of transducers with curvilinear work surface(p. ), with a flat surface of standard samples CO-2 and CO-3, a thicker contact medium or a removable local bath with a wall height of 2-3 mm should be used.

3.5.5. Setting up a flaw detector with a transducer includes setting the operating frequency, setting the depth gauge, setting the control zone, limiting sensitivity, checking the dead zone.

3.5.6. The operating frequency is set by turning on the corresponding buttons on the top panel (UD-11PU, UD2-12 flaw detectors, etc.), connecting the circuits corresponding to the specified frequency and the converter (DUK-66PM, DUK-66P flaw detectors) or by other means in accordance with the instructions for the operation of the device.

When using foreign flaw detectors, thickness gauges and transducers, instead of the operating frequency of 2.5 and 5 MHz, it is allowed to use frequencies of 2 and 4 MHz, respectively.

3.5.7. The adjustment of the depth gauge of the flaw detector for the inclined transducer is carried out according to the standard sample of the enterprise (see Fig. 1) with rectangular risks made on the outer and inner surfaces of the sample. The beginning of the scale is adjusted according to the coordinates of the risks ( S, L 1), when sounding it with a direct beam (Fig. 3), the end of the scale is adjusted according to the coordinates (2 S, L 2), risks on the outer surface when it is sounded by a single reflected beam. The end of the scale can be adjusted according to the risk on the inner surface when sounding with a double reflected beam (coordinates 3 S, L 3).

Depth gauge setup by coordinates S, L(respectively At, X in a flaw detector) is carried out separately for longitudinal and annular marks on the sample.

Echo signals from control marks in the sample must be installed on the flaw detector screen with a height of at least 30 mm.

The amplitude of the echo signal from the flat-bottomed hole must be set on the flaw detector screen with a height of at least 30 mm, while taking into account the accepted position of the control zone on the flaw detector screen in accordance with clause 3.5.10.

3.5.14. When searching for defects, set the search sensitivity with knobs (buttons) REDUCTION is 6 dB less (by value).

3.5.15. The correctness of the limit sensitivity setting of the flaw detector with the transducer should be checked every time the equipment is turned on, as well as every hour of operation.

Verification of the characteristics of the transducer should be carried out using standard samples CO-2, CO-3 at least twice per shift as the transducer wears out.

3.5.16. After adjusting the sensitivity limit, check the dead zone by identifying holes with a diameter of 2 mm in standard sample CO-2, located at depths of 3 and 8 mm in accordance with the requirements of paragraph . If the indicated holes are not detected, it is necessary to repeat the setting of the limit sensitivity in accordance with paragraphs. - or replace the converter.

3.5.17. The speed of scanning the pipe surface by the transducer should be no more than 100 mm/s, the scanning step (between adjacent trajectories) should not exceed half the size of the piezoelectric plate in the transducer used.

It is allowed to use other scanning modes if they are specified in the technical requirements for pipes.

4. ULTRASONIC TESTING

4.1. General provisions

4.1.1. When ultrasonic testing of pipes, the following sounding directions should be used:

1) chordal, perpendicular to the generatrix of the cylinder, - to detect longitudinally oriented defects: scratches, scuffs, cracks, etc .;

2) along the generatrix - to detect transversely oriented defects: cracks, shells, etc.;

3) radial, along the radius, - to detect delaminations, sunsets, as well as to measure the wall thickness.

4.1.2. Pipe wall continuity is monitored by the echo-pulse method according to the combined circuit of switching on the transducer in the contact version. In the control process, transverse-longitudinal movement of the transducer is performed at a speed of not more than 100 im/s with a step between adjacent trajectory lines of not more than half the size of the piezoelectric element.

4.1.3. An example of determining the complexity of pipe control is given in.

4.2. Longitudinal defect control technique

4.2.1. To detect longitudinally oriented defects, chord sounding by an inclined transducer should be used when moving it perpendicular to the generatrix of the cylinder along the entire outer surface of the pipe in one direction, and at the ends of the pipes - over a length equal to twice the wall thickness, but not less than 50 mm, in two opposite directions.

Control parameters are selected according to the table.

Sounding is performed by a direct and once reflected beam. If there are interfering signals in the control zone with a direct beam, it is allowed to sound with a single and double reflected beam.

4.2.2. The limit sensitivity setting is carried out according to the longitudinal risks with a depth h in in the standard sample of the enterprise (see) in accordance with the requirements of paragraphs. - .

4.2.3. The diagram of transducer movement along the pipe surface is shown in Fig. 6a. It is recommended to move the transducer along an arc in sectors 100-150 mm long, depending on the diameter of the pipe, followed by turning the pipe to the appropriate angle to control the next sector.

4.3. Method of control of transverse defects

4.3.1. To detect transversely oriented defects, sounding should be used along the generatrices of the cylinder along the outer surface of the pipe in one direction, and at the ends of the pipes - over a length equal to twice the wall thickness, but not less than 50 mm, in two opposite directions. Control parameters are selected according to the table. Sounding is carried out by a direct and once reflected beam, and in the presence of interfering signals in the control zone - by a direct beam, once and twice reflected.

Schemecontrolwallspipes

a - on thelongitudinaldefects; b - on thetransversedefects

Heck. 6

4.3.2. The limit sensitivity setting is carried out according to the transverse risks with a depth h in the standard sample of the enterprise (see) in accordance with the requirements of paragraphs. - .

4.3.2. The diagram of transducer movement along the pipe surface is shown in Fig. 6b.

4.4. Lamination control technique

4.4.1. End sections of pipes subjected to welding, with a wall thickness of at least 10 mm over a length equal to twice the wall thickness, but not less than 50 mm, are subject to control in order to detect delaminations, sunsets. Sounding is performed in the radial direction by a PC transducer at a frequency of 2.5 or 5.0 MHz, while the transducer is installed in such a way that the acoustic axes of both piezoelectric plates are located in the axial plane of the pipe.

4.4.2. The limit sensitivity setting is carried out along a flat-bottomed hole with a diameter d in the standard sample of the enterprise (see) in accordance with the requirements of paragraph.

4.4.3. The diagram of transducer movement along the pipe surface is shown in .

In the absence of delamination, only the bottom signal 1 from the inner surface of the pipe is observed on the screen of the flaw detector. In the presence of delamination, signal 2 from a defect appears in front of the bottom signal, while the bottom signal decreases or completely disappears.

4.4.4. The dimensions and configuration of the bundles are determined by the conditional boundary. The conditional boundary is taken to be the line corresponding to such a position of the center of the transducer above the defect, at which the signal amplitude decreases to a level of 15 mm, corresponding to 0.5 of the amplitude from the flat-bottomed hole.

Outlining the conditional boundary on the surface of the pipe, the dimensions of the bundle and its conditional area are determined.

4.5. Registration of defects

4.5.1. When an echo signal appears in the control zone, the following characteristics are measured:

Reflector location coordinates;

Reflected signal amplitude;

The conditional extent of the defect along or across the axis of the pipe.

The location of unacceptable defects is marked on the pipe surface with an indication of the depth.

The specified characteristics are determined using a flaw detector configured in accordance with paragraphs. - .

4.5.2. The reflector coordinates "Du" and "Dx" are determined using the depth gauge of the flaw detector in accordance with the flaw detector operating instructions on the scale on the screen (DUK-66PM) or on the digital indicator (UD2-12).

4.5.3. The signal amplitude is measured by the height of the pulse on the screen in mm or by the amount of signal attenuation in dB up to a level of 30 mm.

4.5.4. The nominal length of the reflector is measured by the length of the transducer movement zone along the pipe axis when longitudinal defects are detected or along a circular arc when transverse defects are detected, within which the echo signal changes from the maximum value to a level of 15 mm, corresponding to half the amplitude of the signal from the risk (see p. ).

4.5.5. Defects are subject to registration, the signal amplitudes from which exceed the level of 15 mm on the screen of the flaw detector, i.e. amplitude level 0.5 from a given control reflector: risks, flat-bottomed holes.

4.5.6. Echoes from defects should be distinguished from interfering signals.

The reasons for the appearance of interfering (false) signals can be:

Irregularities in the pipe surface causing the transducer to wobble and cause air gap under the converter;

Excess contact medium;

Risks and protrusions on the end surfaces of the pipe;

Dihedral angle of the prism (with a small transducer boom);

The delay line of the PC converter.

Interfering signals caused by acoustic contact violation or reflections from the corners and the boundary of the transducer delay line are distinguished by the fact that when the transducer is moved, they do not move along the scan line on the screen of the flaw detector.

The sources of signals moving along the scanning line are determined by measuring the coordinates Dx, Dn of reflectors and analyzing them.

A - point allowable defect, the signal amplitude from which does not exceed the amplitude from the control reflector (risks, flat-bottomed hole);

D - point invalid defect, the amplitude of the signal from which exceeds the amplitude from the control reflector;

BD is an extended (regardless of length) invalid defect, the signal amplitude from which exceeds the amplitude level (30 mm) from the control reflector or an extended invalid defect, the signal amplitude from which exceeds the amplitude level 0.5 (15 mm) from the control reflector, and the length exceeds the allowable value for longitudinal and transverse defects ();

BA - extended allowable defect, the signal amplitude from which exceeds the level of 0.5 amplitude (15 mm) from the control reflector, and the conditional length does not exceed the allowable value for longitudinal and transverse defects; or an extended (regardless of length) defect, the signal amplitude from which does not exceed the level of 0.5 of the amplitude from the control reflector;

P - delamination or other defect (sunset, non-metallic inclusion), the signal amplitude from which exceeds the amplitude from the control reflector (flat-bottomed hole);

RA - delamination or other permissible defect, the signal amplitude from which does not exceed the amplitude from the control reflector (when controlled by the PC transducer).

4.6.3. When measuring the thickness of the RS, the transducer must be installed on the surface of the pipe (p.); as a rule, the acoustic axes of both piezoelectric plates must be in the axial plane of the pipe.

5. EVALUATION OF THE RESULTS OF ULTRASONIC TESTING

5.1. Based on the results of measuring the pipe wall thickness, a conclusion is given on compliance with the requirements specified in the technical specifications for pipes or other NTD.

5.2. The evaluation of pipe metal continuity based on the results of ultrasonic testing is carried out in accordance with the requirements established in the standards or specifications for pipes.

5.3. In the absence of technical requirements for assessing the quality of pipes in standards, specifications, drawings, it is recommended to use regulatory requirements in accordance with .

6. REGISTRATION OF THE RESULTS OF CONTROL

6.1. The results of ultrasonic testing of pipes must be recorded in the registration log, in the conclusion, and, if necessary, in the control card.

6.2. The log should show:

Order number;

Number of controlled pipe;

Pipe dimensions and material;

Standard, TU for pipes;

Technical documentation for ultrasonic testing;

The depth of the risks for setting the sensitivity (see );

The area of ​​the flat-bottomed hole in the sample (see);

Type of ultrasonic flaw detector and thickness gauge;

Transducer type and input angle;

Operating frequency of ultrasonic vibrations.

An example of filling out a journal and designing a control card is indicated in.

It is allowed, if necessary, to give an opinion on a batch of pipes of the same size, one steel grade (with a list of rejected pipes and an abbreviated record of defects in accordance with paragraphs,).

7. SAFETY INSTRUCTIONS FOR ULTRASONIC TESTING

7.1. When carrying out work on ultrasonic testing, the flaw detector operator must be guided by the “Rules for the technical operation of consumer electrical installations” and “Safety regulations for the operation of consumer electrical installations”, approved by the USSR State Energy Supervision Authority on December 21, 1984, as well as GOST 12.2.007.0 “Electrical products. General safety requirements” and GOST 12.2.007.14 “Cables and cable fittings. Safety requirements".

7.2. Persons at least 18 years of age who have been instructed in safety regulations (with an entry in the log), who have a certificate of knowledge of the above rules (clause 7.1), as well as production instructions enterprise and this guidance document.

7.3. Safety briefing is carried out in accordance with the procedure established at the enterprise.

7.4. Fire safety measures are carried out in accordance with the requirements of the "Model fire safety rules for industrial enterprises”, approved by the GUPO of the Ministry of Internal Affairs of the USSR in 1975 and GOST 12.1.004“ Fire safety. General requirements".

7.5. Before turning on the flaw detector, the flaw detector operator must make sure that there is a reliable grounding. The grounding of the flaw detector in the workshop must be carried out in accordance with the requirements of GOST 12.1.030 “SSBT. Electrical safety. Protective earth, nulling.

Grounding of ultrasonic flaw detectors is carried out by a special residential portable wire, which should not simultaneously serve as a conductor of the operating current. As a grounding conductor, a separate core should be used in a common sheath with a phase wire, which should have the same cross section as it.

Use neutral wire for grounding is prohibited. The cores of wires and cables for grounding must be copper, flexible, with a cross section of at least 2.5 mm.

7.6. Plug sockets for portable electrical appliances must be equipped with special contacts for connecting a grounding conductor. In this case, the design of the plug connection should exclude the possibility of using current-carrying contacts as grounding contacts. The connection of the grounding contacts of the plug and the socket must be carried out before the current-carrying contacts come into contact; the order of shutdown must be reversed.

7.7. Connecting the flaw detector to the power supply and disconnecting it is carried out by the electrician on duty. At specially equipped posts, a flaw detector can be connected by a flaw detector.

7.8. It is strictly forbidden to work under lifting mechanisms, on unstable shaky structures and in places where damage to the power supply wiring of flaw detectors is possible.

7.9. When using lifting mechanisms at the control site, the requirements of the "Rules for the Design and Safe Operation of Hoist Cranes" approved by the USSR Gosgortekhnadzor in 1969 must be taken into account.

7.12. In noisy workshops, use individual funds noise protection - antinoise - in accordance with GOST 12.4.051.

7.13. Where possible, the workplaces of flaw detectorists should be fixed. If welding or other work involving bright lighting is carried out at a distance of less than 10 m from the place of control, it is necessary to install shields.

7.14. Accessories used by the flaw detectorist: oilers, cleaning rags and paper should be stored in metal boxes.

7.15. During ultrasonic testing, one should be guided by the "Sanitary norms and rules for working with equipment that creates ultrasound transmitted by contact into the hands of workers”, No. 2282-80, approved by the Chief State Sanitary Doctor of the RSFSR on December 29, 1980.

7.16. According to the requirements of sanitary norms and rules No. 2282-80 and order No. 700 of 19.06.84 of the Ministry of Health of the USSR, flaw detectorists entering work must undergo a mandatory medical examination. Hired personnel must undergo a periodic (once a year) medical examination,

7.17. After overhaul and preventive maintenance, flaw detectors with transducers should be checked for acceptable levels ultrasonic field - according to GOST 12.1.001. At the same time, the parameters of the ultrasonic field acting on the hands of the flaw detectorist should not exceed the values ​​given in the sanitary norms and rules No. 2282-80. The results of measurements of the parameters of the ultrasonic field must be documented in a protocol in the form 334, approved by order of the Ministry of Health of the USSR dated 04.10.80 No. 1030.

7.19. To protect hands from exposure to contact media and ultrasound during contact transmission, flaw detector operators must work in mittens or gloves that do not allow contact media to pass through.

In this case, it is necessary to use two pairs of gloves: outer - rubber and inner - cotton or two-layer according to GOST 20010.

7.20. In the cold and transitional period of the year, flaw detectorists must be provided with warm overalls according to the standards established for this climate zone or production.

APPENDIX 1
Recommended
METHODS OF COUPLING THE SURFACES OF THE TRANSDUCER AND PIPE

1. Treatmentsurfacesconverter

In order to ensure reliable contact, the working surface of the transducer is processed to match the corresponding surface of the pipe being tested. It is recommended to have a set of transducers that covers the range of pipe diameters with an interval of ±10% (for example, with transducer surface radii of 31, 38, 46 mm, the range of tested pipes is covered from 57 to 100 mm).

To mark the case (prism) of the transducer, it is advisable to make transparent templates (made of plexiglass) with risks (a) corresponding to the angles of inclination of the acoustic axis of the transducer (30° and 40°). On the prism of the transducer, a line is drawn through the input point, corresponding to the angle α of inclination of the acoustic axis (see b). The template is applied to the body of the transducer, while the acoustic axis of the transducer must coincide with the corresponding line on the template (see c). Then, an arc with a radius is marked on the transducer R. Initially, the prism is processed with a file or on an emery wheel, and then the surface is finished with a sandpaper, which is placed on a pipe segment. The accuracy of finishing is checked using a template.

As the converter wears out, repeat the above operations.

2. Applicationstabilizingsupports

When testing along a cylindrical surface, it is allowed to use stabilizing supports (Fig. 2) fixed on the transducer. The dimensions of the supports depend on the types and dimensions of the transducers used.

Schememarkupandfine-tuningsurfacesconverter

a - template; b - body (prism); c - marking scheme; g - debugging

Heck. 1

Supportforobliqueconverters

indicativedimensions, mm:

A ≤ H; B = in + 2; With = 8 ÷ 12; S = 2 ÷ 3; r = 5 ÷ 7

n =6 ÷ 15 (dependsfromtypeconverter);

a - sketchsupports; b - schemeinstallationssupports

Heck. 2

Support overhang (size h) relative to the transducer surface is calculated by the formula:

R- outer radius of the pipe;

r- support radius;

n- converter boom;

S- support wall thickness.

Examplecalculation.

When checking a pipe with a diameter of 60 mm and dimensions r= 6 mm, n= 12 mm, S= 2 mm

departure h= 1 mm.

It is allowed to use supports of other designs that provide the necessary position of the transducer, for example, nozzles made of wear-resistant material (fluoroplastic, caprolon, etc.)

APPENDIX 2
Reference
TYPES OF CONTACT MEDIUM

1. ContactWednesdayChernivtsiengineeringfactorythem. Dzerzhinsky (copyrightcertificate № 188116)

1.1. The contact medium is an aqueous solution of polyacrylamide and sodium nitrite in the following ratio (%):

polyacrylamide - from 0.8 to 2.0;

sodium nitrite - from 0.4 to 1.0;

water - from 98.8 to 97.0

1.2. Cooking method

In a vessel with a volume of about 10 liters, equipped with a stirrer with an angular speed of 800-900 rpm, 4 liters of water and 1.5 kg of 8% technical polyacrylamide are loaded, stirred for 10-15 minutes until a homogeneous solution is obtained.

Then add 600 ml of 100% sodium nitrite solution.

2. ContactWednesdayon thebasiscarboxymethyl cellulose(copyrightcertificate№ 868573)

2.1. The contact medium is an aqueous solution of CMC, synthetic soap and glycerin - according to GOST 6259 in the following ratio (%):

soap synthetic fatty acid fractions

C5-C6 or C10-C13 (25% solution) - from 7 to 15;

carboxymethylcellulose (CMC) - from 3 to 5;

glycerin - from 1 to 8;

water - the rest

The industry produces carboxymethyl cellulose grades 85/250, 85/350 and others according to MRTU 6-05-1098 in fine-grained fibrous and powdered states.

2.2. The contact medium is obtained by stirring carboxymethyl cellulose in water for 5-10 minutes, then the solution is kept for 5-6 hours until the CMC is completely dissolved.

Note. The consumption of a contact medium of any kind is approximately 0.3 kg per 1 m2 of pipe.

APPENDIX 3
Recommended
REGULATORY REQUIREMENTS FOR PIPES FOR ULTRASONIC TESTING AND EVALUATION OF METAL CONTINUITY

These regulatory requirements can be used for ultrasonic testing of pipes in the absence of technical requirements in standards, specifications or other regulatory and technical documentation.

The object of control is pipes made of carbon and alloy steel grades St3, 20, 15GS, I5XM, 12X11V2MF, etc.

Technicalrequirements

1. Volumecontrol

1.1. The control of longitudinal and transverse defects is carried out in one direction by inclined transducers, shear waves, in a volume of 100% at the ends of the pipes for a length equal to twice the thickness, but not less than 50 mm, in two opposite directions.

The control of delaminations at the ends of pipes over a length equal to twice the thickness, but not less than 50 mm, is carried out by PC transducers (longitudinal waves).

1.2. Wall thickness control is carried out at the ends of the pipes and in the middle part at four points along the perimeter of the pipe with a step of 90°.

2. Sensitivitycontrol

2.1. Sensitivity during control by transverse waves is adjusted according to rectangular risks - according to GOST 17410 with a depth of 10% of the nominal thickness of the pipe wall, but not more than 2 mm, a width of 1.5 mm, a length of 100 mm.

2.2. Sensitivity during control by longitudinal waves is adjusted according to a flat-bottomed reflector - according to GOST 17410:

Diameter 3.0 mm (area 7 mm2) - for pipe wall thickness up to 10 mm;

Diameter 3.6 mm (. area 10 mm2) - for pipe wall thickness over 10 mm to 30 mm;

Diameter 5.1 mm (area 20 mm2) - for pipe wall thickness over 30 mm.

3. Graderesultscontrol

3.1. Unacceptable defects include:

point and extended defects, the signal amplitude from which exceeds the control level (30 mm);

extended longitudinal defects with a reflected signal amplitude of more than 0.5 of the amplitude of the control mark, the nominal length of which is more than 100 mm for pipes with a diameter of more than 140 mm and more than 65 mm for pipes with a diameter of 57 to 140 mm;

extended transverse defects with a reflected signal amplitude of more than 0.5 amplitude from the control mark, the nominal length of which along the arc of the outer surface is more than 50 mm.

Note. The assessment by the depth of the scratches and by the conditional length of the longitudinal and transverse defects is given on the basis of the standards " Technological instructions on ultrasonic quality control of pipe metal "VNIIPTkhimnefteapparatura, Volgograd, 1980, agreed with TsNIITmash, Moscow, 1980, and VNITI, Dnepropetrovsk, 1980, designed to evaluate pipes manufactured in accordance with GOST 8731 and used for the manufacture of steam and hot pipelines water piping of the PPR-600 furnace instead of pipes with technical requirements according to TU 14-3-460.

3.2. Inadmissible delaminations include defects, the signal amplitude from which exceeds the signal amplitude (30 mm) from a flat-bottomed reflector.

3.3. Limit deviations pipe wall thickness should not exceed:

15%, - 10% - for pipes with a diameter of up to 108 mm;

20%, - 5% - for pipes with a diameter of more than 108 mm.

Note. Thickness deviations are indicated in accordance with the requirements of TU 14-3-160.

APPENDIX 4
DETERMINATION OF CONTROL COURSE

The complexity of ultrasonic testing of a pipe includes the time spent on monitoring longitudinal and transverse defects, delaminations at the ends of pipes, and measuring the wall thickness.

The estimated time to move the transducer depends on the speed and scan step and is determined by the formula:

D- outer diameter of the pipe, mm;

L- pipe length, mm;

l 0 is the length of the pipe section to be checked for delamination, mm;

v- scanning speed, mm/s;

t- scanning step, mm

Taking into account the performance of auxiliary operations (setting the flaw detector, measuring and marking defects, recording inspection results, etc.), additional time is required (up to 20-30% of the calculated one). Thus, the total time for pipe inspection is:

T= (1.2 ÷ 1.3) T 0.

For example, to test a pipe with a diameter of 108 mm, a wall thickness of 10 mm and a length of 3 m (with l 0 =50 mm, v=80 mm/s, t= 6 mm) estimated time T0 = 69 min, total labor intensity T= 83-90 min.

It takes approximately 1 minute to measure the wall thickness for each point (to measure four points in three sections - 12 minutes).

D-4.5: D - point invalid defect; 4.5 - location depth (mm);

BD-0-60: BD - extended invalid defect; 0 - defect on the outer surface; 60 - conditional length (mm);

PA< 10: PА - допустимое расслоение, < 10 - эквивалентная площадь (мм2);

2A-8: 2A - two point allowable defects; 8 - location depth (mm).

Map of ultrasonic testing of a pipe (pipe development Ø 89

3. Transverse defects _________________________________________________________

_____________________________________________________________________________

(absent, available - give a list)

4. Point defects _________________________________________________________

_____________________________________________________________________________

(absent, available - give a list)

5. Bundles __________________________________________________________________

_____________________________________________________________________________

(absent, available - give a list)

The pipe is recognized ________________________________________________________________

_____________________________________________________________________________

(good, defective)

Ultrasound flaw detector ______________________________________________ Signature (surname)

Head of NMK Laboratory _________________________________ Signature (surname)

Rules for the Construction and Safe Operation of Pressure Vessels (1987)

E 1.1.1; E 1.1.3; E 1.3.1; E 2.13.2; In 1.1.1; B 1.1.2; In 1.1.6; B 1.1.7

Sanitary norms and rules for working with equipment that creates ultrasound transmitted by contact to the hands of workers (1960)

Page 1

The incoming inspection of pipes should include all types of checks, including flaw detection, to confirm their compliance with the requirements of standards and specifications. Transportation, preparation and inspection casing pipes must be made in accordance with the manufacturer's requirements.

Incoming control of pipes is carried out for their compliance with the technical requirements set forth in the normative and technical documentation for pipes.

The input control of pipes and fittings of foreign supply is also carried out in accordance with the above provisions.

Pipe incoming inspection areas are specialized organizational units and are not subordinate to shops that produce marketable products. The main task of the sites is to check the continuity of pipes, steel grade, grain size and reject defective pipes as much as possible.

During the incoming inspection, pipes and materials must be checked for the absence of defects and deterioration in their quality caused by violations. established rules their storage and transportation. At operational control it is necessary to check the correctness of the preparation of pipes and their assembly for welding, as well as to control the technological parameters of the welding process and the quality of the weld seam processing. It is necessary to control the correctness of the geometry of the groove of the welded pipe edges, the size of the gaps in the joints and the displacement of the welded edges. When using preheating, it is necessary to control the temperature of the heat-affected sections of pipes before and during welding, and in case of electric resistance welding, check the presence and quality of cleaning of the pipe surface under the contact shoes of the welding machine.

The enterprise must carry out incoming inspection of pipes, forgings, parts of welded joints and welding consumables for their compliance with the requirements of these Rules, standards, specifications and design documentation.

The enterprise must carry out incoming inspection of pipes, forgings, parts of welded joints and welding consumables for their compliance with the requirements of these Rules, standards, specifications and design documentation.

An analysis of the accident rate for new tubing (with a service life of up to 5 years) showed that due to the lack of pressure testing during the input inspection of pipes, an additional 3% unnecessary repairs of the total number of PRS. Corrosion destruction is typical for tubing of all plants. Pipes of the Nizhnednepropetrovsk pipe-rolling plant are most susceptible to corrosion, followed by Japanese and Austrian pipes. The deviation of the geometrical parameters of the thread leads to its erosion on the pipes. The percentage of such defects is high in the pipes of the Sumgait, then Nizhnednepropetrovsk, Rustavi, Kamensk-Ural plants. It should be noted high quality threaded connections imported pipes.

An analysis of the accident rate for new tubing (with a service life of up to 5 years) showed that due to the lack of pressure testing during the input inspection of pipes, an additional 3% of unnecessary repairs from the total number of PRS occur. Corrosion destruction is typical for tubing of all plants. Pipes of the Nizhnednepropetrovsk pipe-rolling plant are most susceptible to corrosion, followed by Japanese and Austrian pipes. The deviation of the geometrical parameters of the thread leads to its erosion on the pipes. The percentage of such defects is high in the pipes of the Sumgait, Nizhnednepropetrovsk, Rustavi, Kamensk-Ural plants. It should be noted the high quality of threaded connections of imported pipes.

7.2.1 Incoming quality control of pipes and fittings is carried out by a construction and installation organization authorized to perform installation of pipelines made of polymeric materials.

7.2.2 Input control includes the following operations:

Checking the integrity of the package;

Checking the marking of pipes and fittings for compliance with technical documentation;

External inspection of the outer surface of pipes and fittings, as well as the inner surface of fittings;

Measurement and comparison of outer and inner diameters and wall thickness of pipes with the required ones. Measurements should be made on at least two mutually perpendicular diameters. The measurement results must correspond to the values ​​specified in the technical documentation for pipes and fittings. The ovality of the ends of pipes and fittings that goes beyond the limits of permissible deviations is not allowed.

7.2.3 All foreign pipes and fittings must have a technical certificate.

7.2.4 It is not allowed to use for the construction of pipes and fittings with technological defects, scratches and deviations from tolerances greater than that provided by the standard or specifications.

The results of the input control are documented in an act in the form given in Appendix E.

7.3 Welding and gluing plastic pipes

7.3.1 Connections of pipes and parts made of polymeric materials to be welded must be made by contact heating welding (butt, socket) or by connecting parts with an embedded heating element.

a - alignment and fixing in the clamps of the welding machine of the ends of the welded pipes;

b - mechanical restoration pipe ends using trimming (1); c - checking the accuracy of the coincidence of the ends by the size of the gap (s); d - heating and melting of the surfaces to be welded with a heated tool (2); d - joint draft

Figure 5 - The sequence of the process of assembly and butt welding of pipes by contact heating

When welding, it is necessary to select pipes and fittings according to delivery lots. Welding of pipes and parts made of various polymeric materials is not allowed.

In butt welding, the maximum edge misalignment shall not exceed 10% of the nominal pipe wall thickness.

The inner diameter of the socket of the connecting parts must be less than the nominal outer diameter of the pipe being welded within the tolerance.

7.3.3 In butt welding, immediately before heating, the surfaces to be welded must be subjected to mechanical treatment to remove possible contamination and oxide film. After machining, between the ends of the pipes, brought into contact with the help of a centering device, there should not be gaps exceeding 0.5 mm for pipes with a diameter of up to 110 mm and 0.7 mm for large diameters.

The ends of the pipes for socket welding must have an external chamfer at an angle of 45 ° for 1/3 of the pipe wall thickness.

7.3.4 Butt welding of pipes under installation conditions should be carried out on welding machines that provide automation of the main welding processes and computer control with registration of the technological process (see Figure 5).

To prevent sticking of molten material during pipe welding, the heater should be coated with a heat-resistant anti-adhesion coating.

7.3.5 In flash butt welding using welding machines and mounting fixtures, the following operations should be performed:

Installation and alignment of pipes in a clamping centering device;

Mechanical trimming of pipes and degreasing of ends;

Heating and melting of welded surfaces under pressure;

Removing the welding heater;

Conjugation of heated surfaces to be welded (sludge) under pressure;

Cooling of the weld under pressure.

7.3.6 The main controlled parameters of the butt welding process are: the temperature of the working surfaces of the heater, the duration of heating, the depth of flashing, the value of contact pressure during flashing and upsetting. Height h internal and external burr (rollers) after welding should be no more than 2-2.5 mm with a pipe wall thickness s up to 5 mm and not more than 3-5 mm with a wall thickness of 6-20 mm.

7.3.7 Resistance socket welding includes the following operations:

Marking at a distance from the end of the pipe, equal to the depth of the socket of the connecting part plus 2 mm;

Installation of a bell on the mandrel;

Installation of the smooth end of the pipe in the sleeve of the heating element;

Heating for a specified time of the parts to be welded;

Simultaneous removal of parts from the mandrel and sleeve;

Connection of parts to each other up to the mark with exposure until the melted material hardens.

When welding, the rotation of the parts relative to each other after the mating of the parts is not allowed. After each welding, it is necessary to clean the working surfaces from adhering material. The holding time of the welded products until partial hardening depends on the material used.

7.3.8 Marking of welded joints is carried out immediately after the end of the operation on the hot melt of the outer bead at two diametrically opposite points in the process of cooling the joint in the clamps of the centralizer of the welding machine or mounting fixture.

7.3.9 Welding using fittings with embedded electric heating elements is used to connect plastic pipes with a diameter of 20 to 500 mm with any wall thickness, as well as for welding saddles to the pipeline.

Welding with sockets with embedded heaters is recommended for:

Connections of long pipes;

Pipe connections with a wall thickness of less than 5 mm;

Repair of the pipeline in cramped conditions.

Welding of pipelines using fittings with embedded heaters is carried out at an ambient temperature not lower than minus 5 °С and not higher than +35 °С.

In cases where it is necessary to carry out welding at other air temperatures, work is performed in shelters (tents, tents, etc.) with the provision of heating of the welding zone. The place of welding is protected from moisture, sand, dust, etc.

7.3.10 The technological process of connecting pipes using couplings with embedded heaters includes:

Preparation of pipe ends - cleaning from contamination, marking, mechanical processing (sanding) of welded surfaces and their degreasing. The total length of the pipe ends to be cleaned must be at least 1.5 times the length of the couplings used for welding;

Assembly of the joint (installation and fixing of the ends of the pipes to be welded in the clamps of the centering device with simultaneous seating of the coupling);

Connection to the welding machine;

Welding (setting the welding process program, heating, cooling of the joint) according to Figure 6.

1 - pipe; 2 - mark of fitting of the coupling and machining of the pipe surface; 3 - clutch;

4 - embedded heater; 5 - current-carrying (welding) wires

Figure 6 - Welding of pipes with a socket with an embedded heater

Before machining, the ends of the pipes to be welded for a length of 1/2 of the length of the coupling are marked with the depth of the coupling to indicate the processing zone.

Machining of pipe ends consists in removing a layer of material 0.1-0.2 mm thick from the surface of the marked pipe end, as well as removing burrs. The gap between the welded surfaces of the pipe and the socket part should not exceed 0.3 mm.

The welded surfaces of the pipes after machining and the coupling are thoroughly degreased by wiping with compositions specially recommended for this purpose.

Couplings with embedded heaters, supplied by the manufacturer in individual sealed packaging, opened immediately before assembly, are not subjected to degreasing.

7.3.11 Perpendicularity tolerance of pipe ends and maximum clearance between them are given in Tables 3 and 4 (Figure 7).

Figure 7 - Setting the gap when joining pipes

Table 3 - Tolerance for perpendicularity of pipe ends

In millimeters

Table 4 - Maximum allowable gap between two pipes

In millimeters

7.3.12 The assembly process includes:

Putting the coupling on the end of the first pipe until the ends of the coupling and the pipe are aligned, fixing the end of the pipe in the clamp of the mounting device;

Installing the end of the second pipe at the stop at the end of the first pipe and fixing it in the clamp of the mounting device;

Pushing the coupling onto the end of the second pipe by 1/2 of the length of the coupling until it stops in the clamp of the device or to the mark applied to the pipe;

Connection to the terminals of the coupling of current-carrying wires from the welding machine.

In order to avoid damage to embedded heaters (wire electric coils), putting the coupling on the end of the pipe or inserting the end of the pipe into the coupling is carried out with care without great effort, distortions and scrolling.

The assembled pipes are laid in a straight line without bending and sagging, the coupling current supply terminals are located with the possibility of free maintenance. The parameters of the welding modes are set on the welding machine depending on the assortment of the coupling or are read from a bar code from the coupling or a magnetic card using a sensor, depending on the type of couplings and welding machines used. After turning on the device, the welding process takes place automatically.

After heating is completed, the welded joint can be moved no earlier than after 20 minutes of cooling.

7.3.13 Welding of saddle branches to pipes (Figure 8) is carried out in the following sequence:

Mark the place of welding of the branch on the pipe;

The surface of the pipe at the point of welding of the outlet is cleaned and then degreased;

The welded surface of the outlet, if it is supplied by the manufacturer in a sealed individual package that is opened immediately before assembly, is not subjected to degreasing;

The outlet is installed on the pipe and attached to it with a mechanical clamp;

Welding wires are connected to the contact terminals of the conductor and welding is carried out.

a - outlet with a saddle heater; b - branch with an annular heater; 1 - pipe; 2 - marks of landing of bends and machining of the pipe surface; 3 - branch; 4 - embedded heater; 5 - half collar; 6 - fastening screws; F - the direction of the compression force of the outlet during assembly and welding

Figure 8 - Welding saddles with embedded heaters with a pipe

After cooling through the branch pipe of the welded outlet, drilling (milling) of the pipe wall is performed to connect the internal cavities of the outlet and the pipe.

7.3.14 Quality control of welded joints is carried out in accordance with the regulatory documentation. To assess the quality of welded joints made using couplings and bends with embedded heaters, coupling joints are tested for flattening, and saddle bends - for rupture.

7.3.15 Pipes made of non-welded polymeric materials, including glass- and basalt-plastic, are glued together and overlapped with fittings.

7.3.16 The surfaces to be glued must undergo special mechanical treatment, degrease, and be coated with glue.

7.3.17 The composition of the adhesive or its brand must correspond to the material of the pipeline.

7.3.18 The configuration and dimensions of adhesive joints must be carried out in accordance with special regulations, taking into account the pipes used, the service life and the technology for performing installation work.

7.3.19 The regulations should specify the gluing technology, including the technological processes of surface preparation, and, if necessary, the preparation of the adhesive itself, the gluing process itself, the time before testing the joint, indicating the necessary parameters.