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DL/T 819-2019: The code for the welding heat treatment for power plant
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Basic data | Standard ID | DL/T 819-2019 (DL/T819-2019) | | Description (Translated English) | The code for the welding heat treatment for power plant | | Sector / Industry | Electricity & Power Industry Standard (Recommended) | | Classification of Chinese Standard | F20 | | Word Count Estimation | 20,217 | | Date of Issue | 2019-06-04 | | Date of Implementation | 2019-10-01 | | Older Standard (superseded by this standard) | DL/T 819-2010 | | Regulation (derived from) | Natural Resources Department Announcement No. 7 of 2019 | | Issuing agency(ies) | National Energy Administration | DL/T 819-2019: The code for the welding heat treatment for power plant---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
The code for the welding heat treatment for power plant
ICS 27.100
F 20
People's Republic of China Electric Power Industry Standard
Replace DL/T 819-2010
Technical specification for welding heat treatment in thermal power plant
2019-06-04 released
2019-10-01 implementation
Issued by National Energy Administration
Table of contents
Foreword...III
1 Scope...1
2 Normative references...1
3 Terminology...1
4 General regulations...2
4.1 Personnel...2
4.2 Instruments...2
4.3 Insulation materials...2
4.4 Safety requirements...3
5 Heating method and application conditions...3
5.1 Heating method...3
5.2 Application conditions...3
6 Process...4
6.1 Determination of process documents...4
6.2 Preheating...4
6.3 After heat...4
6.4 Post-weld heat treatment...4
7 Temperature measurement...7
7.1 Selection of temperature measurement method...7
7.2 Thermocouple temperature measurement requirements...7
7.3 Other temperature measurement requirements...9
8 Installation and insulation of heating device...10
8.1 Installation of heating device...10
8.2 Keep warm...10
9 Quality inspection...10
9.1 Quality inspection items...10
9.2 Quality requirements for post-weld heat treatment...11
9.3 Treatment of unqualified post-weld heat treatment quality...11
10 Technical documents...11
Appendix A (Normative Appendix) Technical Conditions of Flexible Ceramic Resistance Heaters...12
Appendix B (informative appendix) Welding heat treatment process card, welding heat treatment operation record, welding heat treatment work statistics...13
Appendix C (informative appendix) Preheating temperature of common steel...15
Appendix D (informative appendix) Post-weld heat treatment temperature and time of common steel...16
Appendix E (Normative Appendix) Quality Evaluation Form of Post-weld Heat Treatment...17
Foreword
This standard is compiled in accordance with the rules given in GB/T 1.1-2009.
This standard is a revision of DL/T 819-2010 "Technical Regulations for Welding Heat Treatment of Thermal Power Plants", and is in line with DL/T 819-2010
In comparison, with the exception of editorial changes, the main technical changes are as follows.
- Added automatic recording of heat treatment equipment and measurement inspection and accuracy requirements of thermocouples;
- Supplement the test requirements of thermocouples and the technical requirements of thermocouple wires;
- Completed the first confirmation requirements of welding heat treatment work instruction or process card;
- Refined the related process of induction heating;
- Adjusted the heating width of flexible ceramic resistance and far-infrared radiation heating large diameter thin-walled tube;
- Added the process requirements for post-heating and post-welding heat treatment of small diameter thin-walled martensitic heat-resistant steel;
- Adjust the post-weld heat treatment constant temperature of some martensitic heat-resistant steel to (740～760)℃;
- Adjusted the zone temperature control requirements of high alloy steel post-weld heat treatment;
- Adjusted the standard chapter structure.
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of the Power Station Welding Standardization Technical Committee.
Drafting organizations of this standard. China Electric Power Research Institute Co., Ltd., State Grid Beijing Fidelity Technology Development Co., Ltd., Suzhou Thermal Engineering Research
Institute Co., Ltd., China Energy Construction Group Tianjin Electric Power Construction Co., Ltd., China Energy Construction Group Shanxi Electric Power Construction Co., Ltd., Jiangsu Fangtian Power
Power Technology Co., Ltd., Shandong Electric Power Construction Third Engineering Company, China Power Construction Group Henan Engineering Co., Ltd., China Energy Construction Group Jiangsu Power
Power Construction Third Engineering Co., Ltd., Wuhan University, China Energy Construction Group Beijing Electric Power Construction Co., Ltd.
The main drafters of this standard. Guo Jun, Qiao Yaxia, Chang Jianwei, Chen Zhongbing, Zhang Yongsheng, Lei Ming, Yang Qingxu, Song Tongle, Sun Songtao,
Wang Xue, Zhuang Haiqing, Ren Yongning, Yang Chao, Zhang Hao.
This standard replaces DL/T 819-2010 from the date of implementation.
The opinions or suggestions during the implementation of this standard are fed back to the Standardization Management Center of China Electricity Council (No. 2 Baiguang Road, Beijing)
Number One, 100761)
Technical specification for welding heat treatment in thermal power plant
1 Scope
This standard specifies the requirements for welding heat treatment of steel weldments during installation, maintenance and factory preparation of thermal power generation equipment.
This standard applies to preheating, post-heating and post-weld heat treatment of weldments.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 1234 High resistance electric heating alloy
GB/T 2614 Ni-Cr-Ni-Si thermocouple wire
GB/T 3375 welding terminology
GB/T 4654 General technical conditions for infrared radiant heaters with non-metallic substrates
GB/T 4989 Compensation wire for thermocouple
GB/T 9452 Method for measuring effective heating zone of heat treatment furnace
GB/T 16839.1 Thermocouple Part 1.Index Table
GB/T 16839.2 Thermocouple Part 2.Tolerance
GB/T 18404 Armored Thermocouple Cable and Armored Thermocouple
GB/T 34035 Field Test Method for Thermocouple
DL/T 752 Technical specification for welding dissimilar steel in thermal power plant
DL/T 868 welding procedure qualification specification
DL/T 869 Welding technical specification for thermal power plant
DL/T 1719 Technical Guidelines for Testing Metal Parts with Portable Brinell Hardness Tester
3 Term
GB/T 3375 and the following terms apply to this document.
3.1
Welding heat treatment
Before welding, during or after welding, all or part of the weldment is heated, kept warm, and cooled to improve the weldability of the workpiece.
Process performance, metallographic structure, mechanical properties and stress state of welded joints. Welding heat treatment includes preheating, post-heating and post-welding heat
deal with.
3.2
Range of soak band
During the heating and constant temperature process, the temperature difference in the full thickness direction of the welded joint is less than or equal to the specified range of the heated metal.
3.3
Width of heating
During the heating process, in order to obtain the required uniform temperature range, the minimum width of the heating source applied. Such as the width of the heating device during electric heating
Degree, the flame heating range during flame heating, etc.
4 General rules
4.1 Personnel
4.1.1 Welding heat treatment personnel include heat treatment technicians and heat treatment operators. Welding heat treatment personnel should be specially trained,
obtain a certificate. Those who have not obtained the certificate can only perform auxiliary work of welding heat treatment.
4.1.2 The responsibilities of heat treatment technicians are as follows.
a) a) Responsible for preparing or reviewing technical documents such as welding heat treatment construction plan, work instructions, process cards, and performing technical
Surgery clarification.
b) b) Instruct and supervise the work of heat treatment operators, and evaluate the post-weld heat treatment process and results.
c) c) Collect, summarize and organize welding heat treatment data.
4.1.3 The responsibilities of heat treatment operators are as follows.
a) Carry out construction according to the welding heat treatment construction plan, work instruction and process card.
b) Record the welding heat treatment process.
c) Self-check for post-weld heat treatment.
4.2 Equipment
4.2.1 Welding heat treatment equipment should meet process requirements, be safe and reliable.
4.2.2 The temperature measurement and control instruments, thermocouples, thermocouple wires and other instruments that need to be measured used in the welding heat treatment shall be verified and valid
Use within the period; the automatic recorder should be periodically verified.
4.2.3 The equipment should have the function of automatic temperature measurement and control during the whole process, and be equipped with an automatic temperature recorder with automatic cold junction temperature compensation.
录装置。 Recording device.
4.2.4 The temperature control accuracy of the equipment should be within ±5℃. For computer temperature control systems, the display device should be equipped with automatic cold-end temperature compensation.
The display temperature should be adjusted based on the display temperature of the automatic recorder.
4.2.5 The data storage device of the welding heat treatment process should have data encryption function, and the name of the data file should be automatically generated and cannot be changed.
4.3 Insulation materials
4.3.1 Insulation materials for welding heat treatment shall meet the following requirements.
a) The thermal resistance R value of the insulation material is not less than 0.35℃·m2/W.
b) The melting temperature of the insulating material for flexible ceramic resistance heating or far-infrared heating is higher than 1150℃.
c) Insulation materials for induction heating have no shielding effect on electromagnetic fields.
4.3.2 Aluminum silicate refractory fiber products, glass fiber cloth, high silica cloth, etc. should be used.
4.4 Safety requirements
4.4.1 In addition to the relevant safety operation requirements, the welding heat treatment operations shall also meet the following requirements.
a) Heat treatment personnel wear necessary labor protection equipment and prevent burns.
b) At least two people participate in the homework at the same time.
c) When using electric heating, prevent the conductor of the heating device from contacting the weldment.
4.4.2 When using infrared thermometers, avoid direct or indirect laser shot into human eyes.
4.4.3 The induction heating shall meet the corresponding safety protection requirements.
5 Heating method and application conditions
5.1 Heating method
5.1.1 The heating furnace meets the following requirements.
a) The measurement method and measurement period of the effective heating zone of the heat treatment furnace should meet the requirements of GB/T 9452, and the measurement period is 6 months. heat
The sign of the effective heating zone of the treatment furnace (valid heating zone inspection certificate) should be hung at an obvious position of the furnace.
b) The temperature uniformity of the effective heating zone in the furnace should reach ±10℃, and the accuracy level of temperature control instruments and recording instruments should reach 0.5.
c) The heating furnace can use electric heating or flame heating.
5.1.2 Flexible ceramic resistance heating and far infrared radiation heating shall meet the following requirements.
a) The technical conditions of the flexible ceramic resistance heater meet the requirements of Appendix A.
b) The far-infrared radiant heater meets the requirements of GB/T 4654.
c) When multiple heaters are used in the same furnace, the deviation of the resistance value of each heater shall not exceed 5%.
5.1.3 Induction heating meets the following requirements.
a) The output power and frequency of the equipment should be able to respond automatically and meet the process requirements.
b) The equipment should be capable of automatic temperature inspection, and should have the function of automatically selecting the highest temperature measurement point for temperature control.
5.1.4 Flame heating meets the following requirements.
a) Oxygen-acetylene gas or other flammable liquid and gas compatible equipment can be selected for heating.
b) Bottles (tanks) or pipelines can be used to provide liquids and gases, and measures should be taken to prevent backfire.
c) The appropriate flame combustion device should be selected according to the size of the weldment and the proposed heating range.
c) A temperature measuring instrument should be equipped to monitor the temperature of the weldment.
5.2 Conditions of use
5.2.1 The heating use of the heating furnace meets the following requirements.
a) Suitable for preheating, post-heating and post-welding heat treatment of weldments.
b) When the size of the weldment is too large and the post-weld heat treatment needs to be performed in sections, the overlapped heating length shall not be less than 300mm.
c) When flame heating is used, the flame should not directly wash away the heated weldment.
5.2.2 Flexible ceramic resistance heating and far-infrared radiation heating are used for preheating, post-heating and post-welding heat treatment of weldments.
5.2.3 Induction heating is used for pre-heating, post-heating and post-welding heat treatment of weldments. For weldments with obvious sharp corner effects, it is not suitable to adopt
Use medium frequency induction heating.
5.2.4 The use of flame heating meets the following requirements.
a) Where it is difficult to use other heating methods, flame heating can be used to preheat and post heat the weldment.
b) Flame heating is not suitable for post-weld heat treatment of high alloy steel weldments.
c) If the flame heating method is used for post-weld heat treatment, a detailed operation plan should be prepared to ensure that the heating is relatively uniform and has a
Effective temperature control measures.
6 Welding heat treatment process
6.1 Determination of process documents
6.1.1 The welding heat treatment process shall be evaluated together in the welding process qualification process according to DL/T 868.
6.1.2 Welding heat treatment operation instructions or process cards (framework) shall be prepared in accordance with the actual specifications of weldments, construction conditions, and welding procedure qualification reports.
For formula refer to Appendix B.1), and confirm the heating range, heating rate,
Constant temperature time and cooling speed can be realized.
6.1.3 The welding heat treatment operation instruction or process card that has been confirmed by the first piece (furnace) and passed the hardness test shall be obtained in the subsequent work
carried out.
6.2 Preheating
6.2.1 The preheating temperature meets the following requirements.
a) The preheating temperature of the weldment should meet the requirements of the work instruction or process card. For the preheating temperature of commonly used steel, see Appendix C.
b) The welding preheating temperature of dissimilar steel can be determined in accordance with DL/T 752.
6.2.2 The heating method and heating width during preheating meet the following requirements.
a) When the outer diameter of the tube is greater than 133mm or the wall thickness is not less than 20mm, it is advisable to use flexible ceramic resistance heating, far infrared radiation heating or
Induction heating.
b) When the thermocouple outside the groove of the monitoring weldment reaches the preheating temperature, it should be kept for a certain period of time to make the temperature of the welding part of the groove reach the required temperature.
begging.
c) When heaters are arranged on both sides of the bevel or fully covered, the heating width is calculated from the edge of the bevel and meets the following requirements
begging.
1) When using flexible ceramic resistance heating or far-infrared radiation heating, the heating width on each side is not less than 4 times the thickness of the weldment, and no
Less than 100mm;
2) When induction heating or flame heating is used, the heating width on each side is not less than 3 times the thickness of the weldment, and not less than 100mm.
d) When the area to be welded is similar to a point, the heating range is based on the welding center as the center and 9 times the maximum depth of the weld as the radius
The nearly circular area.
6.2.3 When re-heating, the following requirements shall be met.
a) After welding is interrupted, preheat again before re-welding;
b) The preheating process is the same as the original preheating process.
6.3 After heat
6.3.1 For weldments with a tendency to cold crack, after the welding work is stopped, if the post-weld heat treatment cannot be performed in time, the post-heating shall be performed immediately. Rear
The thermal process is. heating temperature is 300℃～400℃; holding time is 2h～4h.
6.3.2 After welding the welded joints of martensitic heat-resistant steel, post-heating is not suitable. If it is hot afterwards, it should meet the following requirements.
a) Immediately after the temperature of the weldment drops to 80℃～100℃, and keep it for 1h～2h;
b) Welded joints of martensitic heat-resistant steel with pipe outer diameter not greater than 63.5mm and wall thickness not greater than 10mm can be slowly cooled to room temperature, and
Perform post-heating or post-welding heat treatment within 24h.
6.3.3 The heating width during post-heating shall not be less than the heating width during preheating.
6.4 Post-weld heat treatment
6.4.1 Post-weld heat treatment shall be carried out in accordance with the provisions of DL/T 869, DL/T 752, or other technical documents. Martensite on either side of the weld
For heat-resistant steels, post-weld heat treatment shall be performed immediately after the martensite transformation is completed, otherwise, post-heating shall be performed in accordance with the requirements of 6.3.
6.4.2 Principles for selecting the constant temperature of post-weld heat treatment.
a) It should not exceed the lowest lower transition temperature (AC1) of the deposited metal of the welding material and the base metal on both sides, which should be 30°C below the AC1 temperature;
b) For the welded joints of quenched and tempered structural steel, it should be lower than the tempering temperature during quenching and tempering;
c) For dissimilar steel welded joints, it can be implemented in accordance with the relevant regulations of DL/T 752;
6.4.3 The heating width of pipe butt joints should be selected according to the heating method and the ratio of outer diameter (D) to wall thickness (δ), but at least not less than
100mm. The heating center should be located at the center of the weld, and measures should be taken to reduce the temperature difference between the circumferential and radial directions, and the following requirements should be met.
a) When induction heating is used, determine the heating width as follows.
1) When D/δ≤15, the heating width starts from the center of the weld, and each side is not less than 5 times the pipe wall thickness;
2) When D/δ >15, the heating width starts from the center of the weld, and each side is not less than 6 times the pipe wall thickness.
b) When using flexible ceramic resistance heating or far-infrared radiation heating, determine the heating width as follows.
1) When D/δ≤10, the heating width starts from the center of the weld, and each side is not less than 6 times the pipe wall thickness;
2) When 10＜D/δ≤20, the heating width starts from the center of the weld, and each side is not less than 7 times the pipe wall thickness;
3) When 20＜D/δ≤40, the heating width starts from the center of the weld, and each side is not less than 9 times the pipe wall thickness;
4) When 40＜D/δ≤70, the heating width starts from the center of the weld, and each side is not less than 12 times the pipe wall thickness;
5) When D/δ >70, the heating width starts from the center of the weld, and each side is not less than 15 times the pipe wall thickness.
c) For the heating of the pipe seat weldment, the main pipe side should adopt the method of full-circle heating or circular heating. The heating width of the main pipe and the connecting pipe side shall be according to the main pipe
Determined separately with the thickness of the pipe.
6.4.4 Determination of the constant temperature time of post-weld heat treatment.
a) The constant temperature time of post-weld heat treatment should be determined comprehensively according to the material category, heating method and weldment thickness.
b) The constant temperature time should be determined according to the thickness of the weldment. For medium and low alloy steel, the constant temperature time should be calculated according to 2min/mm～3min/mm, the minimum
30 min; for high alloy steel, the constant temperature time should be calculated as 3min/mm～5min/mm, and the minimum is 60 min. When using induction heating
The value should be biased to the lower limit of the above calculation; when flexible ceramic resistance heating or far-infrared radiation heating is used, the value should be biased to the above calculation
The upper limit.
c) For pipe sockets or rework weldments, the constant temperature time can also be determined by the nominal thickness δ′ of the weldment instead of the thickness δ of the weldment, but it should not be less than
30min. The nominal thickness δ′ of the weldment can be calculated according to the specific weld structure.
6.4.5 Refer to Appendix D for the post-weld heat treatment constant temperature and constant temperature time of common steel.
6.4.6 The control requirements for heating rate and cooling rate are as follows.
a) When using flexible ceramic electric heating and far-infrared electric heating, the heating rate and cooling rate of welding heat treatment are 6250/δ (unit. ℃)
/h, where δ is the thickness of the weldment at the groove, the unit is mm), when medium frequency induction heating is used, the heating rate of the welding heat treatment is
8000/δ, the cooling rate is 6250/δ. The maximum heating and cooling rate shall not exceed 300℃/h. When the wall thickness is greater than 100mm,
The heating rate and cooling rate are controlled at 60℃/h; the heating and cooling rate is not controlled below 300℃.
b) When the outer diameter of the tube is not greater than 108mm and the thickness is not greater than 10mm, if induction heating or flame heating is used, the rise may not be controlled.
Temperature speed.
c) For pipe sockets or rework weldments, the heating rate and cooling rate of welding heat treatment shall be calculated according to the wall thickness of the main pipe.
d) When the heating furnace is performing post-weld heat treatment, the weldment should be heated with the furnace during the heating process; the temperature of the welding should be reduced with the furnace during the cooling process until it is below 300℃
It can be cooled before being released.
6.4.7 During the constant temperature process of post-weld heat treatment, the difference between the data displayed by any two thermocouples should conform to the specified temperature range and not exceed
50°C.
6.4.8 When formulating post-weld heat treatment process measures, the following possible factors should be considered and corresponding measures should be taken.
a) For steel grades with a tendency to reheat cracks, the constant temperature of the post-weld heat treatment should avoid the sensitive temperature range.
Pass the sensitive temperature range quickly.
b) For steel grades with the second type of temper brittleness, the post-weld heat treatment adopts rapid cooling.
c) The loading tools used for cold drawn welded joints can be removed after the welding heat treatment is completed.
d) For the welded joints of the pipeline that have been operated, the hardness of the weld and the base metal shall be inspected before and after the heat treatment. If necessary, metallographic
test.
e) For the welded joint formed by the valve body and the pipeline, during post-weld heat treatment, ensure that the constant temperature temperature of the valve body does not exceed the operating temperature of the valve body.
f) For welded joints with wall thickness greater than 100mm, measures shall be taken to control the temperature difference in the wall thickness direction to meet the heating temperature requirements.
7 Temperature measurement
7.1 Selection of temperature measurement method
7.1.1 The temperature measurement method should be selected according to the heating method. Flexible ceramic resistance heating, far-infrared radiation heating, induction heating should adopt contact method
Temperature measurement; flame heating should adopt non-contact temperature measurement.
7.1.2 Thermocouple, thermometer pen, contact surface thermometer, etc. should ...
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