4.3　Boiler Steel Structures Erection and Secondary Grouting

4.3.1　The upright column docking and framework assembly shall be carried out on the firm and stable assembly frame which shall be leveled.

4.3.2　For the assembly of boiler steel structures，the 1m elevation points shall be drawn at the first section of upright column.When drawing the 1m elevation line on the first section upright column of the multilayer steel frame，the upright column 1m elevation point shall be determined according to the column top elevation of the first section upright column，and the error shall be recorded.

4.3.3　The allowable deviation of assembly components of boiler steel structures shall meet the requirement of Table 4.3.3.

4.3.4　For boiler steel structures in the subsection erection mode，the erection of next layer must be carried out after the former erection layer is aligned.The next procedure erection shall not be carried out when the frame is not aligned.

4.3.5　When conducting the erection and alignment of boiler steel structures，the 1m elevation point of the first section upright column shall be measured according to the plant reference elevation point，and the elevation of upper layers shall be measured on the basis of this 1m elevation point.

4.3.6　The lifting of boiler steel structures shall ensure the structure stable and firm.If necessary，the temporary reinforcement measures shall be taken.Upright column verticality，the main girder deflection and the main dimension of each part shall be re-inspected after lifting the framework.

4.3.7　When erecting the framework connected by welding，it shall be aligned and fixed by spot welding，and the proper welding shrinkage shall be reserved.The formal welding operation can be started after the dimensions have been re-inspected and meet the corresponding requirements.The welding method and sequences shall be noticed during welding，and welding deformation shall be strictly controlled.

4.3.8　The column top arc backing plates supporting roof beams shall be erected according to the requirement of equipment technical documents.The direction of backing plates shall be accurate，and the upper and lower surfaces of backing plates shall be contacted well.

4.3.9　When using high strength bolts，the storage and transportation，safekeeping，erection，inspection and acceptance shall be carried out according to the requirement of GB 50205 Code for Acceptance of Construction Quality of Steel Structures and JGJ 82 Code for Design，Construction and Acceptance of Steel Structures by High Strength Bolt Connection.In addition，the following provisions shall apply:

1　The torque-pretension coefficient of heavy-hex high strength bolt assembly and the tightening axial force（the pre-tension）of the twist-off-type high strength bolt assembly shall be provided with the manufacturer's quality certificates and inspection reports before leaving the factory，and the sampling re-inspection shall be carried out timely before using，and the reinspection shall be witness sampling inspection.

2　During the manufacture and erection of steel structures，the slip coefficient of faying surfaces of high strength bolt assembly shall be tested and re-inspected according to the requirement of Appendix G in this Part.For the components processed at site，the slip coefficient of faying surfaces shall be tested separately，and its result shall meet the design requirements.

3　High strength bolt assembly during the process of storage，transportation and construction shall be stored and used strictly by batch numbers.The bolts，nuts and washers in different batches shall not be mixed together when using.

4　The installation of high strength bolts shall not be forced with any external driving force（such as tapping with a hammer）.If bolts can not be inserted smoothly，the screw hole shall be repaired with a reamer，and gas flame cutting shall not be allowed to use.

5　The final tightening of steel frame high strength bolts in the same layer（section）shall be completed in the same day.The corrosion protection shall be timely taken on the butt joint parts and the local gap of the joint parts shall be blocked by filling putty.

6　The final tightening torque of heavy-hex high strength bolt assembly shall be inspected within 1h-48h after the final tightening completion.And the inspection results shall meet the requirement of Appendix G in this Part，the inspection quantity and method shall meet the following requirements:

1）Inspection quantity.The random inspection propotion is 10% according to the node number，and the inspection number shall be no less than 10.For each random-inspection node，the random inspection proportion of bolts is 10% according to the bolt number and the inspection number shall be no less than 2.If heavy-hex high strength bolt assembly are equipped in the upper/lower beam joint face of the overlapped plate girder，it shall be regarded as one group of nodes，and the random inspection number of bolts in each girder shall be no less than 20.

2）The inspection method shall meet the requirement of Appendix G in this Part.

7　After the final tightening of twist-off-type high strength bolt assembly，the quantity of those bolts without removing their plum heads during final tightening shall not exceed 5% of node bolts，except that the plum heads are not removed by the special spanner due to the structure.For all twist-off-type high strength bolt assembly without removing their plum heads，the torque method or turning angle method shall be adopted for final tightening and they shall be marked.And the final tightening torque inspection shall be carried out according to the requirements of Appendix G in this Part.The inspection quantity and method shall meet the following requirements:

1）The inspection quantity.The random inspection proportion is 10% according to the node number，and the inspection number shall be no less than 10 nodes.For the twist-off-type high strength bolt assembly without removing plum heads of the random inspection nodes，the final tightening torque shall be inspected.

2）The inspection method shall meet the requirement of Appendix D in this Part.

8　The erection and inspection of high strength bolts shall be documented as follows:

1）The re-inspection information of high strength bolting connection sets.

2）The slip coefficient test document.

3）The initial tightening torque and the final tightening torque records.

4.3.10　For the erection of components connected by welding，their own weight and temporary load shall be taken into account for the total length of any temporary positioning spot welding，and the number，thickness and length of spot welding shall be determined by calculation.

4.3.11　The allowable deviation for the erection of boiler steel structures shall meet the requirements of Table 4.3.11.

4.3.12　Before bearing load，hydrostatic test，after filling water for hydrostatic test，after discharging water used for hydrostatic test，and before ignition start-up of the boiler，the vertical deflection of the plate grider shall be measured and the measurement data shall meet the manufacturer's design requirements.

4.3.13　For the erection of the overlapped main girders，the bolting force shall be even and the clearance between the upper and lower beam joining surfaces shall be less than the manufacturer's regulated value.

4.3.14　During lifting boiler steel structures，the settlement observation locations shall be erected in time according to the design requirements，whose layout shall meet the requirements of GB 50026 Code for Engineering Surveying and JGJ 8 Code for Deformation Measurement of Building and Structure.

4.3.15　Enough expansion clearance shall be reserved at the bolting connection parts with the expansion displacement，and the expansion direction shall be paid attention to.

4.3.16　The platforms and ladders shall be erected synchronously together with boiler steel structures.The welding connection shall be timely and firm，and the hangers and fixtures shall be connected timely and tightly.

4.3.17　The rail posts shall be vertical and uniformly spaced.And one post shall be installed near the turning.The rail posts in all platforms at the same side shall be aligned as vertically as far as possible.After the erection of the platforms，ladders，rails and toe plates dampers，they shall be flat and firm，and the joint locations shall be smooth.The installation clearance of toe plates shall meet the drawing requirements.

4.3.18　The inclination or footboard height of the ladders and the connecting platform spacing shall not be changed arbitrarily.

4.3.19　The form metal boards，the flashings and the edge boards of boiler roof shall be fixed tightly and reliably.The corrosion resistant painting and sealing shall be complete.The quantity and the spacing of connecting pieces shall meet the design requirements and the requirements of GB 50205 Code for Acceptance of Construction Quality of Steel Structures.

4.3.20　Prior to the secondary grouting of the steel frame foundation，inspection shall be carried out to confirm wherter the installation of pad irons，adjusting bolts，anchor bolts and foundation rebars and so on is completed and the surface oil contamination，welding slag and other sundries shall be removed completely.The secondary grouting of steel structure foundation shall meet the drawing requirements and the requirements of GB 50204 Code for Acceptance of Constructional Quality of Concrete Structures.

4.3.21　When the column bottom plates are delivered separately，the secondary grouting should be completed before installing the columns.Otherwise，the secondary grouting of steel sturcture foundation shall be carried out after the alignment of the first layer frame.