CONSTRUCTION OF A DIVERT OVER CROSS


In pipeline construction when there is an obstruction such as bridge, culvert, large drain, utilities then we need to proceed our work either under or by the side of the existing obstruction, There are mainly two ways which are Divert Crossing and Under Crossing. Again Divert crossing are two types; Divert Under and Divert Over. Today I will share some pictures with details about a divert over cross of water pipeline.


Procedure of Construction

 1.This is the before construction picture  15m long bridge through which we have to carry on our pipeline work. As the depth of this bridge is very high it will be difficult to go under the bridge. So in this case we will follow the Divert Over Crossing method.





2. In the above pictures workers are trying to prevent soil collapse. For this work we need 1m3 bags, brick chips and an excavator to fill the bags with brick chips & set the bags in the desired position. 



                                       

                                       

                                       

                                       

                                       
3. As during the construction we have to excavate one side of the road so road extension work is necessary for traffic. To do this work first we extend the opposite side of construction with soil and to make it stable use sheet pile. We have to make a finished surface with brick chips because it will be difficult for the traffic to go over the soil when it becomes wet due to rain. 


                         
   4. This is 1200mm dia steel pipe which we will install by the side of the bridge.  




5. On both sides of the bridge we have excavated upto 1.5m for sheet pile driving. Sheet pile driving is essential to protect the from collapsing.






                                         6. In this case our required depth of excavation is 4m. So we use 8m Heavy sheet pile here. The equipment we will use here is LHV (Light Hammer Vibro). It is a hydraulic equipment.





 7. Within this time we will complete the Steel pipe welding work 25 KVA welder.

                                     8. To do welding work bottom side of the pipe we have to keep the pipe in hanging position. We can also provide shade by this way.

                                  9. During the welding work inside the pipe it becomes to much hot which makes the workers uncomfortable. So have to keep cool inside by using cooling fan.




                                     10. After sheet pile driving we will proceed the excavation work.




                                                              11.When welding work finish we have to check the welded joint. There is several method to check. Here we use Ultra Sonic Test. This is a method in which a sound wave is pass through the joint. If there is any void inside the joint this wave will not pass and need to repair the joint.


                                       12. When excavation finish we need to do CC casting of 100mm thickness with C20 concrete.





                                13. After CC casting Re-bar binding work will start and finish form setting work.




                  14. When form setting and rebar binding finish we will do Base Casting by C25 conrete. In this case we use ready mix concrete.



                                                     





















     15. Then we will proceed Steel pipe installation and welding & grinding work. In this case first we install the middle part of the pipeline (which will be exposed). After that we have to check the elevation of the pipe. When elevation is ok then we will install the bend pipe on both side. After that we again need to check the elevation of the pipe.









                                            16.After finishing the installation we need to fix the pipe by providing Protection concrete at bend position on both side because the thrust force is very high at this position which will try to displace the joint.
                                       
 


                                                 17. After 7 days of curing we will remove the form work and start back filling work. Within this time we will remove sheet pile.During back filling proper compaction is needed.






                                               18.After back filling to the required depth we start Flat soling, Haring soling and Macadam work.


                                                19. This is a picture of a Divert Over crossing after construction with Air Valve installed.

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