NB/T 10349-2019Technical Code for Safety Inspection of Steel Penstocks (English PDF)

Foreword

This standard is in accordance with GB/T 1.1-2009 "Guidelines for Standardization Part 1: Standard Structure and Compilation". Drafting.

This standard replaces DL/T 709-1999 "Technical Regulations for Safety Testing of Penstocks", compared with DL/T 709-1999, except The main technical changes besides editorial changes are as follows.

--- Added the content of corrosion assessment (see 7 Corrosion Inspection);

- Supplement the content of TOFD inspection, modify the length ratio of weld inspection (see 8.4, 8.6);

-Supplement and improve the content of stress testing (see 9 Stress Testing, 8 Stress Testing in DL/T 709-1999);

- Supplement and perfect the content of vibration detection (see 10 Vibration detection, 9 Vibration detection in DL/T 709-1999);

- Deleted the content of water quality and bottom quality testing (see DL/T 709-1999, 10 Water quality and bottom quality testing);

--Added the content of recheck calculation (see 11 Recheck calculation).

1 Scope

This standard specifies the content and testing technology for safety testing of penstocks in in-service hydropower projects Claim.

This standard applies to the safety inspection of in-service penstocks in hydropower projects.

2 Normative references

The following documents are indispensable for the application of this document. All dated quotations Only the dated version applies to this document. For undated references, the most The new version (including all amendments) applies to this document.

GB/T 1172 Conversion value of hardness and strength of ferrous metals

GB/T 3323 Radiography of welded joints of metal fusion welding

GB/T 11345 Ultrasonic testing technology, testing level and assessment for non-destructive testing of welds

GB/T 29712 Acceptance level of ultrasonic testing for non-destructive testing of welds

GB 50766 Code for production, installation and acceptance of penstocks for hydropower and water conservancy projects

NB/T 35056 Hydropower Station Penstock Design Code

NB/T 47013.4 Non-destructive testing of pressure equipment Part 4: Magnetic particle testing

NB/T 47013.5 Non-destructive testing of pressure equipment Part 5: Penetration testing

NB/T 47013.10 Pressure Equipment Testing Part 10: Ultrasonic Testing by Diffraction Time Difference Method

3 Basic regulations

4 Patrol inspection

4.1 The testing organization shall follow the inspection records of penstocks provided by the operation management unit, etc.

Operation management data, on-site inspections. See Appendix A for the on-site inspection record sheet.

4.2 The patrol inspection of exposed pipes shall include the following.

a) Inspection of pipe body deformation and displacement;

b) Check the operation and water seepage conditions of the expansion joints;

c) Check the sealing performance of manholes and other openings and pipes;

d) Check the working condition of the vent or air valve;

e) Check the operation status of drainage facilities;

f) Check the displacement and settlement of buttresses and piers;

g) Check the support movement and lubrication condition;

h) Seal inspection of the connection between the main valve and the steel pipe.

4.3 The underground pipeline inspection should include the following contents.

a) Leakage inspection along the buried pipe;

b) Inspection of the operation status of groundwater drainage facilities;

c) Check the sealing performance of manholes and other openings and pipes;

d) Check the operation or damage status of related monitoring instruments.

4.4 The patrol inspection of buried pipes in the dam shall include the following.

a) Inspection of downstream dam surface cracks;

b) Water seepage inspection on downstream dam surface;

c) Check the displacement and deformation of the downstream dam surface.

4.5 The patrol inspection of steel-lined reinforced concrete pipes shall include the following.

a) Inspection of circumferential cracks in the upper bend section;

b) Inspection of circumferential cracks in oblique and straight sections;

c) Inspection of axial cracks in oblique and straight sections;

d) Water seepage of the expansion joint and inspection of the expansion stroke;

e) Check the sealing performance of manholes and other openings and pipes;

f) Check the operation status or damage status of related monitoring instruments.

5 Appearance inspection

5.1 Before appearance inspection, one should understand the production, installation, and acceptance of penstocks, and major defects Deal with the situation, operation, repair, maintenance and various abnormal situations that have occurred during operation.

5.2 In the process of appearance inspection, the inspection should be focused on rework and operation during the production and installation of penstocks A site that has been abnormal.

5.3 The results of the appearance inspection should be recorded in time. See Appendix B for the appearance inspection record sheet. when necessary Recording and description can be carried out using auxiliary methods such as video recording and photographing.

5.4 Appearance inspection should use level, ruler, caliper, tape measure, feeler gauge and weld inspection ruler And other necessary measuring tools and equipment.

5.5 Appearance inspection parts should mainly include pipe body, support ring and support, expansion joint, connection part Bit.

5.6 The appearance inspection of the pipe body shall include the following.

a) Deformation of pipe wall depression, bulge, etc.;

b) Corrosion condition of the pipe wall;

c) Surface defects of the main stressed welds;

d) Damage and deformation of the stiffener ring;

e) Grouting hole and surrounding conditions;

f) Damage and deformation of the manhole cover.

5.7 The appearance inspection of the support ring and the support should include the following.

a) Deformation and damage of support ring and support;

b) The operating status and contact status of the support;

c) Corrosion condition of support ring and support.

5.8 The visual inspection of expansion joints shall include the following.

a) Deformation and damage;

b) Operating status; c) Corrosion conditions.

5.9 The appearance inspection of the connection part shall include the following contents.

a) The appearance of the connecting part of the penstock and the concrete structure such as the pier, dam body and wall body situation;

b) The connection status of the penstock and the stiffening ring, support ring, and expansion joint;

c) The connection status of the penstock and the main valve;

d) The void condition of the concrete surrounding the penstock.

6 Material testing

6.1 Material quality certificate and production and installation acceptance documents and other materials can prove that the materials conform to When required by the design documents, material testing is not required.

6.2 When the material grade is unclear or there are doubts about the material grade, a material test shall be carried out and the material shall be determined. Material grade and performance.

6.3 When the site conditions permit, samples should be taken for mechanical performance test and chemical composition analysis.

Determine the material grade and performance. The sampling point should be located at a place where the force is small and easy to repair, and The repair measures should be determined in advance, the sample cutting part should not have sharp angles, and the periphery should be in a circular arc transition.

The radius of the arc should not be less than 3 times the plate thickness and not less than 30mm.

6.4 When the site conditions do not allow sampling, a spectrum analyzer or the Analyze the chemical composition of the material by drilling a chip sample, and measure the hardness of the material at the same time, according to GB/T 1172 Carry out intensity conversion, and determine the material grade and performance through comprehensive analysis.

6.5 When penstocks are found to have quality problems that affect safe operation, they should be straightened on the steel pipes.

Take samples for mechanical performance test, chemical composition analysis and metallographic analysis to determine the material grade And performance.

6.6 After a damage accident occurs to the penstock, samples should be taken from the damaged pipe section for mechanical properties Test, chemical composition analysis and metallographic analysis to determine the material grade and performance.

7 Corrosion detection

7.1 Corrosion testing shall include corrosion status testing and corrosion volume testing.

7.2 Measuring tools such as tape measure and ruler should be used for corrosion detection, and corrosion detection should be used Thickness gauges, depth sounders, depth vernier calipers and other measuring instruments and measuring tools.

7.3 Corrosion detection should be segmented according to the upper flat section, inclined pipe section, lower flat section, etc., or according to the steel pipe circumferential seam In charge of the section.

7.4 The surface of the inspected part should be cleaned before the corrosion amount test to remove the adhesion on the steel pipe surface Waste, sludge, scale, etc.

7.5 The corrosion detection shall meet the following requirements.

a) On different pipe sections, select pipe sections with relatively heavy corrosion and no less than 30% as Detection object;

b) On the selected pipe section, at least 3 cross-sections should be selected for each pipe section for measurement.

Each section is divided according to the longitudinal welding seam, and there should be no less measuring points in each inspection area. At 3;

c) For more severely corroded pipe sections or pipe sections, it is advisable to appropriately increase the inspection section and Point quantity

d) The surface coating of the pipe wall should be removed during testing. When measuring with coating, the corresponding The thickness of the coating.

7.6 The degree of corrosion shall be evaluated according to the results of corrosion condition testing and corrosion amount testing, and is divided into Class A, Class B, Class C, Class D. The evaluation requirements should meet the following requirements.

a) Grade A is slightly corroded. […]