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Stainless steel seamless/Welded Tubes and pipes Division which is having four full die Pilger Mills, four Draw benches for manufacturing cold finished seamless tubes and pipes and four welding lines for manufacturing welded tubes and pipes. |
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Carbon Steel & Alloy Steel Seamless Tubes and Pipes Division which is having four draw benches for manufacturing cold finished seamless tubes. |
Carbon Steel, Alloy Steel & Stainless Steel Seamless Tubes/Pipes Seamless Tubes/Pipes are manufactured by either cold drawing process or cold pilgering process.
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| Cold Drawing Process |
In this method the tube is drawn through a die, either with or without internal support, the resultant tube being stronger, tougher and harder. If further reductions are required the tube must be annealed to bring t back to a ductile state. It can be seen that desired mechanical/physical properties can be achieved by cold drawing. There are two basic methods of cold drawing... |
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Sink Drawing |
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Plug Drawing |
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| Sink Drawing Process |
During a sinking operation the tube, which has been cold drawn to finish wall, and close outside diameter dimensions, is drawn through a die without internal support. This method is used for drawing tube into various shapes or as a sizing operation on the outside diameter where only a small reduction is required. There, is however, a minor thickening of the wall hi this process. |
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| There are two main methods of plug drawing... |
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| Fixed Plug |
A Lubricated tube is fed over the plug, attached to the Plug Bar, and the tagged end of the tube is gripped in the jaws of the drawing carriage of ‘DOG’. The DOG engages on the moving draw bench chain and the tube is pulled over the plug and through the die. |
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| Floating Plug |
This method uses a Tapered Plug, which has the facility to move, this ensures that the drawing forces are in equilibrium and gives far better positioning of the Plug.
At HMTL Prime Quality Hot Extruded Mother Pipes (our raw material) are used which are mostly imported from reputed mills around the world. Tungsten Dies and Mandrels/Plugs are used to ensure blemish free quality. We have two separate plants, one to manufacture Cold Drawn Seamless Carbon Steel and Alloy Steel pipes and tubes and another to manufacture Cold Drawn Seamless/Welded Stainless Steel pipes and tubes.
Cold Drawing is carried out several times till the tubes are brought down to the required size. After each cold drawing the tubes are subjected to heat treatment, straightening and surface cleaning. The finish tubes are then subjected to extensive testing as per the requirements of the code and also those of the customer’s before they are dispatched to customer. |
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At Heavy Metal & Tubes Limited, we have got ten imported Pilger mills for getting good quality products at faster rates. These pilger mills are run by experienced skilled operators. Required size of mandril and roller set is taken and assembled before starting new size. One by one tube at a time is fed in the mill. Periodic size and surface of product is checked. The rollers are +getting drive from the motors. The Pilgering is an alternative process to Drawing of tubes and pipes. In the Pilgering process, higher area reduction (70-80%) can be achieved resulting in the final product in say one pass against say three passes for the same sizes in the Drawing process.
Additional tests such as Eddy Current, Ultra Sonic, Inter Granular Corrosion, Microscopic Examination Air under Water Surface Roughness, etc are carried out if asked specifically by the customer.
Finish pipes/tubes are marked with Electric Etching/Paint. Each pipe/tube is marked as “Manufacturing Std – Grade of material Size - Heat No - Third Party inspection Stamp to Co-relate with our Test Certificate. |
