Страница 4: ДСТУ EN 12952-6:2015. Котли водотрубні та допоміжне устатковання. Частина 6. Огляд під час виготовлення документації та маркування складників котлів, що перебувають під тиском (62758)

Radiographic testing of welds shall be carried out in accordance with EN 1435.

The acceptance criteria for internal imperfections of welds detected by radiography shall be in accordance with Table 9.4-1.

Acceptance limits for imperfections occurring in the body of the weldment have been derived by reference to EN ISO 5817 and EN ISO 6520-1.

The requirements of the above standards have been supplemented to reflect current water-tube boiler manufacturing practice. Where this has been done, an identifying letter “S” has been utilized in Table 9.4-1 in the column “EN ISO 5817 level”.

Table 9.4-1 —Acceptance criteria for weld internal imperfections detected by radiography

Table 9.4-1 (continued)

Table 9.4-1 (continued)

Ultrasonic testing of welds shall be carried out in accordance with EN ISO 17640.

EN ISO 17640 shall be fully applied to ultrasonic testing of welds during manufacture of water-tube boilers in accordance with this European Standard. However, the following specific requirements shall be met and specified in a testing procedure when options are permitted by these standards:

1. austenitic steels: ultrasonic testing of fusion welded joints in austenitic materials shall be carried out in accordance with written procedures based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired;

2. partial penetration welds: ultrasonic testing of partial penetration welds shall be carried out in accordance with written procedures based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired;

3. the examination level В shall be in accordance with EN ISO 11666. The specific test requirements for the testing shall be specified in a written instruction according to EN ISO 17640 and be made available for the UT-operator. The assessment shall be in accordance with acceptance level 2 according to EN ISO 11666;

4. transverse defects: ultrasonic testing for transverse defects shall be performed:

1. on steel group 1.2, where the thickness of parent material is 40 mm and over;

2. on steel groups 2, 3, 4 and 5 for all parent material thicknesses;

5. tandem testing technique: the tandem testing technique shall not normally be applied to water-tube boilers;

6. probe frequencies: probes with a frequency between 1,5 MHz and 5 MHz shall be used for normal application. Specific applications requiring frequencies outside this range shall be based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired;

7. parent metal testing: parent metal in the area of the scanning zone shall be ultrasonically tested with a normal probe before testing with an angle probe if the edge zone of the parent metal has not been previously examined before welding;

8. preparation of the surface: scanning surfaces and surfaces from which the sound beam is reflected shall be assumed to be satisfactory if the surface roughness is not greater than 12,5 pm;

NOTE 1 Roughnesses greater than this value can still be acceptable if it can be demonstrated that effective ultrasonic testing can be achieved.

9. signal to noise ratio: during the testing of a weld, the noise level, excluding spurious surface indications, shall be at least 12 dB below the evaluation level required;

10. measurement of the length of defects: the length of reflectors, in either the longitudinal or transverse direction shall be normally determined by using the half amplitude method (6 dB technique);

NOTE 2 Other methods can be used, based on the manufacturer's own proven practices which should ensure that, by their use, the safety of the boiler is not impaired.

11. height measurements; where EN ISO 17640 is applicable, defect height measurement shall not be necessary. For application outside the scope of EN ISO 17640, the examination level and the acceptance criteria shall be based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired;

12. application of ultrasonic testing for thicknesses less than 8 mm: ultrasonic testing of fusion welded joints in material 8 mm thick, or less, shall be carried out in accordance with written procedures based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired;

13. the examination level В shall be in accordance with EN ISO 11666. The specific test requirements for the testing shall be specified in a written instruction according to EN ISO 17640 and be made available for the UT-operator. The assessment shall be in accordance with acceptance level AL 2.

The acceptance criteria for ultrasonic testing of welds shall be acceptance level AL 3 according to EN ISO 11666.

The following information shall be provided as a minimum in the test reports:

1. identification of the water-tube boiler component;

2. identification of the welds examined and the scanning pattern used;

3. identification of the fusion welding procedure specifications;

4. the stress relief or heat treatment condition;

5. the surface preparation prior to the testing (e.g. machined, ground, as welded);

6. the testing procedure reference;

7. the details of application of the procedure (e g. type of magnetization, consumables used, type of radio­graphic source, type of probes);

8. the reference for acceptance criteria;

9. the results of the testing, including the details of any repairs;

10. in the case of percentage testing, the extension zones of testing, if any are required, and their results;

11. the conformity of the results with this European Standard;

12. the date when the testings were carried out;

13. the name and qualification of the personnel responsible for the testing, the evaluation and interpretation;

n) the date of the report.

10. Final inspection

    1. Visual and dimensional examinations

Visual and dimensional examinations shall be carried out using the approved drawings.

All inspection shall be carried out visually, but may be supplemented by the use of suitable auxiliary means when necessary. The type and performances of any additional examinations shall be based on the manufacturer's own proven practices which shall ensure that, by their use, the safety of the boiler is not impaired.

The final inspection shall be carried out on each pressure part of the water-tube boiler. The inspection shall be carried out in the manufacturer's workshop or at the erection site.

The safety-relevant dimensions and the location of the components in the water-tube boiler, the departure of circularity, and the deviations from straight line of cylindrical components and drums shall be examined. The pitches and the conformance to the design of tube holes shall be spot-checked.

The surfaces shall be examined for imperfections, especially in the case of formed components. In cases where the components have not been formed, or where the examination of surface imperfections has already been carried out during manufacture, the final inspection shall be restricted to the inter-connection areas.

The installation of drums and headers, connecting pipework and tube walls, separators, coolers in water-tube boilers shall be checked for the adequacy of support and support expansion arrangements.

The internal attachments in drums and other components shall be checked where practicable.

The accessibility of access and inspection openings, and the suitability of such openings for the insertion of inspection equipment, shall be checked.

For major components designed to operate in the creep range, the provision and location of the creep measuring devices shall be spot-checked (e g. measuring points of expansion, surface replications).

The test pressure to be used on water-tube boiler components and complete boiler assemblies shall be determined in accordance with EN 12952-3:2011, 5.7.4.

The hazards involved in pressure testing shall be considered by the manufacturer and adequate precautions shall be taken.

NOTE 1 Since it is necessary to avoid the risk of repeated over-pressurization, it is recommended that, prior to the witnessed hydrostatic test, a preliminary examination of the water-tube boiler or component should be carried out at the maximum allowable pressure for the purpose of identifying any significant leaks.

NOTE 2 Care should be taken to ensure that the complete pressure envelope, its supports and its foundations are capable of withstanding the total load that will be imposed upon them during the pressure test

Water shall be used as the pressurizing agent. The quality of the water used shall be such as to prevent both corrosion and any residue of injurious solids.

The completed water-tube boiler, and any components which are required to be hydrostatically tested before assembly into the water-tube boiler, shall be tested with a water at a temperature such that the risk of freezing is avoided. The temperature of the water used for the pressure test shall be selected by the manufacturer taking into account the risk of brittle fracture of the pressure parts, but in any case the temperature selected for the pressure test shall not exceed 50 °С.

The water-tube boiler, or component being tested, and their connections shall be vented, or evacuated, to prevent the formation of air pockets. However, small pockets of trapped air may remain after filling, and the procedure with regard to these shall be based on the manufacturer's own proven practices which shall ensure that, the safety of the boiler is not impaired.

All temporary tubes, connections and blanking devices shall be designed to withstand the appropriate test pressure.

No component undergoing pressure testing shall be subjected to any form of shock loading, e.g. hammer testing, thermal shock, or rapid pressure changes.

The full test pressure shall be maintained for 30 min for completed water-tube boilers and large components, and for an appropriately lesser time for smaller components

Prior to close examination, the test pressure shall be reduced to not less than the maximum allowable pressure.

Pressure parts which have been repaired following the hydrostatic test shall again be hydrostatically tested in accordance with 10.2, after completion of the repair and any required post-weld heat treatment and non­destructive testing, unless otherwise agreed. Such an agreement shall be based on the manufacturer's own proven practices which shall ensure that, the safety of the boiler is not impaired.

10. Documentation

The manufacturer shall produce a design and manufacturing data dossier.

This dossier shall be delivered to the purchaser on completion of the contract.

As a minimum, the manufacturer's data dossier shall contain:

1. a description of the water-tube boiler;

2. the location of the identification markings of the water-tube boiler (see Clause 12);

3. the water-tube boiler general arrangement drawings;

4. the pressure parts general drawings;

5. a resume of the different pressure parts thicknesses and corrosion/erosion allowances;

6. the list of parent materials, together with a copy of material certificates;

7. the list of filler materials;

8. the list of welding procedure specifications used which make reference to corresponding approved welding procedures;

9. the list of welders involved in the manufacture and erection with the reference number(s) of their qualification;

10. the extent and location of non-destructive testing, together with a list of non-destructive testing procedures used and a list of operators with the reference number(s) of their qualifications;

11. details of any approved design modifications/manufacturing concessions (deviations) which have been carried out during the manufacturing stage;

12. the hydrostatic test certificate(s).

12 Marking

Each water-tube boiler and each component submitted to the individual test shall be permanently and legibly marked to show the identity and origin of the boiler, and the permissible operating parameters.

For each water-tube boiler or component, this marking shall be affixed above the manhole of the main steam and water drum, or preferably on a plate permanently attached to a principal pressure part of the boiler.

The marking shall include the following:

1. name and address of the manufacturer;

2. serial number;

3. year of manufacture;

4. maximum allowable pressure and temperature;

5. date of first hydrostatic test and test pressure;

6. number of this European Standard;

7. reference number of the responsible third party organization, if applicable;

8. CE marking, if applicable;

MCR (Maximum Continuous Rating).Annex A
(normative)

Special requirements for composite tubes

A.1 General

This annex specifies requirements for the inspection during construction; documentation and marking of chemical recovery boilers as defined in EN 12952-5:2011, E.2. These special requirements are additional to all the other requirements of this European Standard which shall continue to apply.

A.2 Special requirements of qualification of welding procedures for fusion welding

A.2.1 General

The general requirements of this European Standard, mainly Clause 6, shall be supplemented by application of the specific requirements in A.2.2.

Flash butt welding shall be carried out in accordance with EN 12952-5:2011, E.6.

A.2.2 Application of EN ISO 15614-1 to composite tubes

A.2.2.1 Range of qualification

Only a qualification of WPS obtained with composite tubes shall be applied for welding of composite tubes.

The nominal thickness 1 is the total nominal thickness of a composite tube Diameter D is the nominal diameter of a composite tube.