4.3　Pressure Parts

4.3.1　The installation of drum and header shall be in accordance with the following requirements:

1　Before fabrication and installation，the drum and header shall be checked and meet the following requirements:

1）Before installation，the internal of the drum and header shall be cleaned，guarantee there is no debris and blocking；

2）There isn't mechanical damage and distortion on the surface of drum and header and the weld tube，and there aren't defects such as cracks，craters，and air bubbles，etc.in the weld and heat affected zone；

3）The location of the drum and header shall comply with the regulation of equipment technical documentation.

2　The hoisting of drum and header of waste heat boiler shall be carried out after the steel frame installation is aligned and fixed；while aligning the drum and header，carry out inspection to the center line of drum and header and the separation distance between drum and header（Figure 4.3.1-1）according to the installation datum lines of vertical and horizontal and elevation datum line.The allowable deviation of drum and header installation of waste heat boiler shall comply with the regulation of Table 4.3.1-1.

3　The hoisting of drum and header of tube box type waste heat boiler shall be carried out after the steel frame and tube box installation is aligned and fixed；while aligning the drum and header，carry out inspection to the center line of drum and header and the separation distance between drum and header（Figure 4.3.1-2）according to the installation datum lines of vertical and horizontal and elevation datum line.The allowable deviation of drum and header installation of waste heat boiler shall comply with the regulation of Table 4.3.1-2.

4　Before drum and header installation，carry out checking to the supporting device，the contacting positions shall be matched，the partial clearance should not be larger than 2mm；the contacting between support and girder shall be well without shaking；the hoisting device shall be fixed，spring hoisting device shall be temporarily fixed；

5　When the boiler and header are located，expansion clearance shall be reserved for the support as per the regulated expansion direction in the equipment technical documentation，and shall be fixed temporarily；

6　The installation of drum internal devices shall be in accordance with the following requirements:

1）According to the product design，check the boiler internal components；

2）All adjoining plane of flanges shall be tight；

3）The connecting components shall be fixed connected and the locking device shall be available；

4）After the installation of internal device is finished，remove the debris inside the drum.

4.3.2　Before installation，the heating surface tubes shall be checked and in accordance with the following requirements:

1　There aren't defects on the surface of tubes，such as cold-laps，cracks，flatten，and serious corrosion；when there are nick，pitting and other defects on the tube surface，the defective depth shall not exceed 10%of the tube nominal thickness，and the effective thickness of the defection part shall not be less than the required min thickness calculated through tube strength；

2　Carry out spectrum checking to the alloy steel tubes one by one，the material shall comply with the regulation of design documentation，and identification shall be carried out；

3　Carry out appearance checking and adjusting to the convection tubes，the tube adjustment platform shall be smooth and fixed，the error of lofting dimension shall not be larger than 1mm，and the regulated tube and the lofting line shall be matched，the partial allowable deviation shall be-2mm-0，and carry out trial installation；

4　The heating tubes shall be orderly arranged，the allowable deviation between partial part of the tube and the design installation position shall be 0-5mm；

5　Before assembly and installation，separately carry out ball passing test to the heating tubes with numbered balls，the test balls shall not be plastic distorted and remained inside the tube；after test，the tube shall be sealed，and the checking record shall be available；the diameter of the test ball shall comply with the regulation of Table 4.3.2；

6　The heating tube shall be kept clear，no debris could be left during the process of installation.

4.3.3　The installation of membrane water wall shall be in accordance with the following requirements:

1　The water wall assembly shall be carried out on the firm fabrication frame；

2　The allowable deviation of the water wall components assembly shall comply with the regulation of Table 4.3.3-1；

3　The allowable deviation of the stiffening bar assembly（or installation）shall comply with the regulation of Table 4.3.3-2；

4　The hoisting point for the water wall components shall be reasonably chosen and the components shall be properly fixed.During the process of transferring and hoisting，permanent distortion shall not be caused；

5　The water wall should adopt ground entire pre-assembly；

6　The sealing weld shall be carried out to the water wall according to the requirement of equipment technical documentation，there aren't missing welding and wrong welding in weld joint.

4.3.4　The pressure elements welding shall be in accordance with the following requirements:

1　The weld technology regulation for the pressure elements shall be available；

2　The heating tube should use mechanical cutting，when adopt flame cutting，the machining allowance shall be remained；

3　When the base metal is welded，the welding groove shall be smooth and free from scale，rust，grease，or other debris；

4　The welder code or weld joints setting drawing shall be printed through low stress steel stamp nearby the weld joint of the boiler pressure elements and test samples；

5　The welding joint between heating tube and proper pipes shall be smooth，the stagger thickness shall not be larger than 10% of the pipe thickness and shall not larger than 1mm；

6　When carry out butt welding，the allowable inclined valueΔf（Figure 4.3.4）of the pipe end face shall comply with the regulation of Table 4.3.4-1；

7　If the tube distortion is caused by welding，the tube linearity shall be measured by ruler at 50mm from the weld joint center，and the allowable deviation of the welded tube linearity shall comply with the regulations of Table 4.3.4-2；

8　Except the molding pipe fittings of welded，forged，and cast，the butt weld joint shall not be arranged in the pipe bend，and the distance from the weld joint to the pipe bend shall not be less than the pipe diameter，and shall not less than 100mm；the distance from the weld joint to the border of supports and hangers shall be larger than 50mm；

9　The surfaces of pressure element weld joint and the heat affected zone shall be smooth without slags，cracks，incomplete fusion，craters and blow holes；weld joint height shall not be lower than the surface of base metal；the weld joint and base metal shall be smoothly connected；the undercut depth of weld joint shall not be larger than 0.5mm，the full-length of undercut of both sides shall not be larger than 20% of the pipe perimeter，and shall not larger than 40mm；

10　After the appearance of circular welding joint of heating pipe，proper pipe and other pipe fittings are checked to be qualified，carry out radiographic detection or ultrasonic detection according to requirements of the engineering technical documentation and standard，the detection shall meet the relevant requirements of the current professional standard Nondestructive Examination for Pressure Equipment NB/T 47013，the weld joint quality shall meet the relevant requirements of the current professional standard Boiler Safety Technical Supervision Administration Regulation TSG G0001；

11　While carrying out radiographic detection or ultrasonic detection，the detection quantity shall meet the relevant requirements of the current professional standard Boiler Safety Technical Supervision Administration Regulation TSG G0001 and the following regulations:

1）When the detection result is unqualified，besides carrying out reworking to the unqualified weld joints，the twice samples selected from weld joints of same type by the same welder shall be rechecked as unqualified.If the rechecking is still unqualified，carry out detection to all weld joints of same type by the same welder；

2）When the weld joints are detected to be unqualified，analyze the reason，prepare viable reworking program for approving，the reworking shall not be more than twice at the same position.After reworking，carry out appearance checking and detection again.

12　All affiliate weld assembly of the boiler pipe shall be completed with welding acceptance before pressure test.

4.3.5　The assembly and installation of superheaters，evaporators，economizers，and desuperheaters shall be in accordance with the following requirements:

1　The assembly and installation of superheaters，evaporators，and economizers shall be carried out according to the following sequence:

1）Header alignment and fixation；

2）Datum serpentuator installation，alignment，and fixation；

3）Install other tube array.

2　The allowable deviation of assembly and installation of superheaters，evaporators，and economizers shall comply with the regulation of Table 4.3.5；

3　Before installing pipe piece，the rapping stem should be installed in positon and shall be fixed with temporary supports；

4　Before the desuperheater is installed，check the fabrication sealing certificate provided by manufacturer and the appearance；the pipe junctions shall be smooth with correct welding；the desuperheater is installed with correct direction.

4.3.6　Before the pressure test，the waste heat boiler shall be in accordance with the following requirements:

1　The pressure test only can be carried out after the pressure system and auxiliary equipment of the waste heat boiler are completely installed.

2　Except safety valves and meters，the pressure test shall be carried out to all pipelines，valves together with the boiler proper.According to the requirement of the boiler equipment technical documentation，the pressure test shall be separately carried out by the heating surfaces of different pressure classification.

3　Before pressure test，the boiler pressure system shall be checked and in accordance with the following requirements:

1）Records for constructions and inspections are available；

2）The internal and surface of the drum and headers shall be cleaned；

3）Manholes，handholes of the pressure elements shall be sealed；

4）The expansion indicating devices are normal；

5）The safety valves shall be isolated，and other valves shall be closed；

6）The temporary devices，which influences pressure test，shall be removed；

7）The glass tube level gauges shall take part in the pressure test of working pressure but not overpressure test.

4　While carrying out pressure test，at least 2 adjusted qualified pressure gauges shall be installed in the testing system，the range of the pressure gauges shall be 2 times-3 times of working pressure.When the rated working pressure is higher or equal to 2.5MPa，the accuracy class of pressure gauges shall not be lower than class 1.6；when the rated working pressure is less than 2.5MPa，the accuracy class of pressure gauges shall not be lower than class 2.5.

5　The test pressure of the boiler pressure test shall be subject to the table 4.3.6.

6　The pressure test shall be in accordance with the following requirements:

1）The pressure test should use water as pressure test medium，and it shall be carried out with ambient temperature higher or equal to 5℃，if the ambient temperature is lower than 5℃，antifreezing measures are required；

2）The water applied to pressure test shall be clean.Water temperature shall be higher than the ambient dew point temperature but not higher than 70℃.When carry out pressure test to alloy steel pressure components，the water temperature shall be higher than the brittle transition temperature of all steels；

3）When filling water to boiler，open the atmospheric relief valve at boiler highest position，after the water is fullly filled and air is totally discharged，then close the air valve；

4）While carrying out pressure test，the water pressure fluctuation speed shall not exceed 0.3MPa/min；when the water pressure is boosted to working pressure，stop boosting pressure and check whether there is water leakage or abnormal situation；then boost pressure to test pressure and keep for 20min；after the pressure is decreased to working pressure，carry out checking again，during the checking process，the pressure shall be kept same，the water drops and water mist shall not be found out on the metal wall and weld joints of boiler pressure components，and visible residual deformation shall not be found out.

7　When the boiler pressure test is unqualified，reworking is required.After the reworking is qualified，carry out pressure test again；

8　After the boiler pressure test is carried out，discharge the water inside the boiler in time.Open the air valves when discharging water；

9　The test records shall be carried out to the pressure test of every time，after the pressure test is qualified，carry out certificate issuing.The certificate of pressure test shall be filled in as per the Table 7.5.1 of this code.