Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
(OP)
Dear All,
Recently we received an order of an Air Cooled Cooler that is fabricated completely of Titanium.
This bundle is a replacement of an exact copy which was built several years ago by another fabricator.
The tubesheet is 25mm thick and the tubes haves a wallthickness of appr. 2,11mm, Dia 25,4mm.
In the original drawing the tube to tubesheet connection is made by rolling.
Two grooves are added in the tubesheet.
Now I am wondering if anybody has some experience with rolling a Titanium tube to tubesheet connection?
What about equipment, rolls, rollingpercentage?
Does anybody has some tips or tricks? Thanks in advance!
If you need additional information please let me know.
Please let me know,
Kind regards,
Euroweld
Recently we received an order of an Air Cooled Cooler that is fabricated completely of Titanium.
This bundle is a replacement of an exact copy which was built several years ago by another fabricator.
The tubesheet is 25mm thick and the tubes haves a wallthickness of appr. 2,11mm, Dia 25,4mm.
In the original drawing the tube to tubesheet connection is made by rolling.
Two grooves are added in the tubesheet.
Now I am wondering if anybody has some experience with rolling a Titanium tube to tubesheet connection?
What about equipment, rolls, rollingpercentage?
Does anybody has some tips or tricks? Thanks in advance!
If you need additional information please let me know.
Please let me know,
Kind regards,
Euroweld





RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
http://www.timet.com/datasheets-and-literature
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
Thanks, that is helpful. Information is practical, I will read it carefully.
Do you have some personal expierence with this topic?
Thanks Euroweld
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
On the other hand, your tubes are quite a bit thicker than what I have have experience with. My experience is more in the range of 0,5 mm thick so I don't know what the effectg would be on tubes that thick.
rmw
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
You want to use the least expansion that gives good joint strength.
I have seen people used a group of 6 shallow grooves or even just a roughened hole ID in the tubesheet.
You will need to use 5 pin rolls and good torque control (do not roll to size, this will not give consistent sealing).
How will the unit be shipped after fabrication?
You will probably need to leak test and then do some re-rolling after delivery.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
I agree with your response. Do you know of any publications that discuss the potential for cracking of thin wall tubing when expanding into tubesheets with square edged grooves? To me, it seems more like "good engineering practice" and just plain common sense to avoid this combination, but current standards and specifications do not prohibit this arrangment, even though it may be evident in the heat exchanger industry.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
This is a thin tubesheet for such thick tubes. For tubesheets like this I am more accustomed to seeing tubes with walls no more than 0.7mm.
= = = = = = = = = = = = = = = = = = = =
Plymouth Tube
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
I agree that cracking is not a concern for such thick tubes (2.11 mm, 0.083", 14 BWG) for the air cooler case described in this thread. When you had mentioned that you had seen the use of 6 shallow grooves it raised my question of groove design regarding the thinner wall tubes like 0.70 mm, 0.028", 22 BWG and thinner walls. Note that titanium tubes as thin as 0.40 mm, 0.016", 27 BWG are being installed, with potential for even thinner tubes of 0.30 mm, 0.013", 30 BWG. These thin walled tubes are mainly used for applications such as steam surface condensers. Either no grooves or shallow multi v grooves are typically used for these condenser tubesheet holes. The shallow grooves provide a higher pull out loading.
rmw mentioned his experience would be to not groove tubesheets with titanium tubes, and his experience has been with the thinner wall tubes of 0.5 mm, 0.020", 25 BWG. rmw reference to grooves may be the TEMA type square edged grooves.
Although this information may not apply to the original question of this thread, it may be known by a few manufacturers or users that use of grooves of the squared edged type should be avoided when expanding thin wall tubes because of the potential for cracking at the groove area. This would apply to both mechanical roller expansion and hyrdraulic expansion. When using the hydraulic expansion process, grooved holes are required to effect a seal. Common groove is a wider squared edged type, TEMA notes as 1/4" wide.
I believe the potential for cracking of thin walled tubes in square edged grooved tubesheet holes exists. Many manufacturers, like rmw's company, do not use grooves to avoid cracking of the tube. Some manufacturers will use the shallow grooves as you describe when pull out loading dictates.
Since there are few articles written on this matter, I ask the question does anyone have experience with thin wall tube cracking at grooves or know of any publications that discuss the potential for cracking of thin wall tubing when expanding into tubesheets with square edged grooves? Comments welcomed.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
For your case, you might want to contact the tube supplier for their recommendations on tube expanding. If you take a look at Valtimet Technical Standards (see link) under the Tube To Tubesheet Attachment section, it recommends for mechanical expansion a tube wall reduction range of 5-12%. I believe the % wall reduction might be on the lower end of the range when expanding into like materials. Also note the caution when using the hydraulic expansion method with thick wall tubes.
You did not mention if the tubes will be welded to the tubesheets. If welded, you may be aware that titanium requires special procedures and a high level of cleanliness during the welding process. The tubes would first be expanded into the tubesheets then followed by welding. Avoid any lubricants on the rollers as they may contaminate the weld. Some manufacturers have used a dry roller approach or a safe refrigerant fluid as a lubricant. Suggest you discuss the welding techniques with professionals who do this work often.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
To checkout their website just type "A-M-H.com in the address line.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
I am not aware of any shell and tube or steam surface condenser manufacturer who use the process you mention. Also, I have not seen this type expanding process specified or approved by the refinery, chemical or power industry customers who buy shell and tube heat exchangers and power plant surface condensers. Are there any technicle articles written that desribe this type expanding process specific to the the shell and tube and condenser industry?
The groove you describe might be similar to the standard TEMA groove of 1/8" wide by 1/64" (0.015") depth. Are the titanium tubes you mention for the heat exchangers thin wall 22 BWG and thinner, or a heavier wall tube? I know that certain standards like API limit wall thickness to a heavier wall than 22 BWG. My concern will continue to be with the expanding of thinner wall tubes (22-30 BWG) into square edged grooves and the potential for cracking regardless of the expanding process. Cracking has certainly been experienced with expanding into over size holes, expanding beyond the backside of the tubesheet and excessive expanding torque and pressure.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
I haven't asked about any standards or approvals as ll our work is in house or on site, nothingfor the ousiide and based on some recent work done supposedly by compenet people I have have to try it.As Imentioned in another post this tooling is likethe toaster waiting on sliced bread. It's taken a long timefor me to find this a it's been out there for a number of years.
I realize your concern hope we cna find out moreinformation.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
Our service is HNO3/Organic Oxidation.
I hope this picture works. You may have to print it.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
Wow, when I think of Ti tubes, I usually think in terms of 22-23-24 ga. wall thicknesses.
rmw
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
The heaver wall tubes have proved a blessing in disguise as now they are seeing a little corrosion on the reboilers.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
I could not open the picture you attached, besides, you mention 18 BWG tubes, and I am talking about the thinner tube walls like rmw mentions, including 25 and 27 ga now being used for power plant condenser applications.
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
RE: Rolling of Titanium Tube-Tubesheet connection Air cooled Cooler
See attached sketch of the shallow multi v groove design for thin wall tubes, 22 thru 27 BWG, that is best when rolling these thinner tubes. The TEMA type square edged grooves and similar may cause tube cracking or splitting of these thin walls. This design may be similar to the shallow grooves mentioned by EdStainless.