Removable Tube Sheet Heat Exchangers
Tube removal is a procedure that involves cutting tubes, pulling elsewhere tubes and tube stubs, and still knocking tubes out of the vessel in Removable Tube Sheet Heat Exchangers. You be able to look to Elliott for all your tube removal needs ranging from tube cutters to tube tuggers to pneumatic hammers. The tube removal development includes several process steps that must be performed with critical sequencing and tolerances. The initial step of our process is the Tungsten Inert Gas (TIG) shrinking of the tube to-tube sheet expansion joints (where applicable), which is performed with our standard plug removal TIG system. For hard rolled and tubes the shrinking process is necessary to relieve the radial stress between the tube and tube sheet. The TIG process is carefully monitored for power and travel so that only designated areas in the tube are shrunk. For some tubes with minimal tube sheet contact, shrinking is not required.
Application :
Tube Removers-One or a combination of the three below methods is used to remove a tube from a boiler or chiller vessel.
Tube Cutters – Tube Cutters are used to internally cut from the inside to the outside of the tube behind the tube sheet on one end. This lessens the force required to pull a tube. To eliminate tube cutting chips in the vessel, tubes should be scored and not totally cut through. The tube cutter needs to have sufficient reach to cut behind the tube sheet. Proper lubrication and cutting speed will increase cutting blade life.
Tube Pullers – Used to break the seal and pull expanded tubes from a tube sheet. A spear or expanding collet is inserted and engaged into the tube inner diameter. A ram or gun applies force to exert an extracting force on the tube. The power to pull the tube is generated manually or through an hydraulic pump. The hydraulic pump can be manually, electrically or pneumatically driven. The pulling force required will vary with the tube size and wall, the depth of the tube sheet and tube material.
Pneumatic Hammers -Pneumatic Hammers are an alternative method to remove tube stubs from heat exchangers and boilers. Maintenance technicians use piloted knockout tools to avoid damage to the tube sheet. The knockout tool is inserted into the tube and the impact pneumatic hammer is actuated to punch out the tube stub.
Tube Installation (Tube Expanders) – Tube Expanding is the art of reducing a tube wall by compressing the outer diameter of the tube against a fixed container such as rolling tubes into tube sheets, drums, ferrules or flanges. Construction of heat exchangers, boilers, and surface condenser tubes is mainly limited to copper, steel, stainless steel, and cast iron with exceptions such as the use of titanium in ultra high pressure vessel applications. To assure a proper tube joint, the tube wall must be reduced by a predetermined percentage dependent upon the material the tube is constructed.