Well, if the batteries on your protable tube stretcher aren't fully charged, this can be a problem.
Kidding aside, it really depends on what the tubes are made of, how long they are, and how long they need to be. In some cases, heat treating can cause a tube to grow in length. In other cases, however, they could shrink. Some tubes can be welded on while others cannot. In some cases, running tubes through a rotary straightener will cause them to grow, while in other cases, running them through a straightener will ruin the tube.
I saw heat exchanger tubes that were short. They rolled one end in, then they put heater tapes into the the tubes and warmed them to about 250F. They grew about 1/2". They yanked the heater tapes and rolled the other end.
They started working around the outside of the shell and then worked the way in toward the center.
Tubes are SA210 A1 carbon steel, 2 1/2" OD. MWT is 0.203"
Length of stock is 20 feet.
Need to grow individual tubes in a tube panel by about 3/8" to meet gap requirements for WPS.
Figure we can locally heat the short tubes with a tiger torch or a rosebud along the 20 foot length and get the desired stretch out of them. Am unsure of the issues of tube deformation or weakening the tube at the joint location.
Am wondering if there is a procedure to follow in order to do thid.
I have seen it done by heating the inside of the tube, but have no access to do an internal heating in this case.
Figure we can locally heat the short tubes with a tiger torch or a rosebud along the 20 foot length and get the desired stretch out of them. Am unsure of the issues of tube deformation or weakening the tube at the joint location.
Am wondering if there is a procedure to follow in order to do thid.
Forget this approach. You go this route you will have problems with residual stresses in the weld joint. If I was the customer and you did this, I would revoke your code stamp.
tigwired;
Appreciate your feedback. Tell your client this technically unacceptable and poor engineering practice. The 3/8" gap is just too large for this approach.
If your process will stand or allow a backing ring I would contact the Imperial Weld Ring Co. and discuss your problem. Not recalling the numbers but I've seen their products take up a lot of space.
How many do you have that are short?
I have to go against the reasoning in the above posts by saying that I've seen pipe heated to make up and welded in the heated condition. The heat was applied using a clamshell type heater about 6' long with just enough heat to get the fit up needed. For years we heated pipe for bending and to pull inline for make. A majority of this piping was put in service, steam (750F} and vaporised heating oil (750F}. If there was any doubt the pipe was stressed relieved with same heaters. These pipe have been in service over 50 years.
I have also seen some replacement boiler tubes that were short, no projection through the drum for welding. these tube were heated to get the required projection then rolled and welded while still heated.
