Double groove expanded tube to tubesheet joint
Double groove expanded tube to tubesheet joint
(OP)
The company I work for builds many shell and tube heat exchangers to ASME Section VIII Div 1. Typically they are low pressure low temperature exchangers (15psi/250 deg F). Almost always, we use double groove expanded tube-to-tubesheet joints. The grooves in the tube hole are typically located off center towards the tubeside face of the tubesheet. Does it matter where the grooves are located within the tube hole? From what I can find, TEMA does not specify. Is there anything wrong with placing the grooves on center or near the shellside face? My thought is that is really doesn't matter, but I am curious of what others typically see and if there is any logic to the groove location.





RE: Double groove expanded tube to tubesheet joint
May I suggest you try posting this in forum391: Heat Transfer & Thermodynamics engineering ? You might get a response there.
Patricia Lougheed
Please see FAQ731-376: Eng-Tips.com Forum Policies: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
RE: Double groove expanded tube to tubesheet joint
RE: Double groove expanded tube to tubesheet joint
U may need to post this question in the boiler and pressure vessel forum and not this forum.
-jehan
RE: Double groove expanded tube to tubesheet joint
Please also refer to the replies posted in the Exchangers forum to piaengr, to the same question.
gr2vessels
RE: Double groove expanded tube to tubesheet joint
In my experience as a pressure vessel engineer I have never come cross any tube to tubesheet joint detail or a standard where the annular grooves are closer to the shell face of the tubesheet. you are however correct to state that many standards and codes do not comment on this detail.
-jehan
RE: Double groove expanded tube to tubesheet joint
Howzat?
cheers,
gr2vessels
RE: Double groove expanded tube to tubesheet joint
RE: Double groove expanded tube to tubesheet joint
Note that TEMA requires both grooves to be in the base metal unless specified otherwise by the purchaser. See RCB-7.44.
-Christine
RE: Double groove expanded tube to tubesheet joint
cheers,
gr2vessels
RE: Double groove expanded tube to tubesheet joint
It was indeed an eye opener to me to know of cladding being on the SHELL side and grooves closer to shell side face of tubesheet as I have not come across such a detail. i would appreciate if you could post the sketch of such a type of tube to tubesheet joint
regards,
jehan
RE: Double groove expanded tube to tubesheet joint
A whole documentation is near you, for a S&T exchanger (sea water cooler), Ti tubes and Ti cladded tubesheet, ask Deepak for this exchanger documentation in the 2006 Shell project. You could also refer to your own reply in the thread330-208578: Titanium tubesheet Clad of Solid? dated 01.02.2008 in the Metal and Metallurgy engineering forum. Also, Google words like "tubesheet cladding groove" and you'll be surprised how many hits will pop-up (and prop-up the groove cut in the cladding). The principle is to cut the groove as close as possible to the source of corrosive environment, to prevent the penetration of the fluid between the hole and the tube, in case that the seal weld of tube to the CRA clad is not possible or is not practical.
cheers,
gr2vessels
RE: Double groove expanded tube to tubesheet joint
I have an older Airtool brochure that shows two grooves and makes no reference to location or codes
Here are our design conditions.
Use 3 groves if physically possible with 2 grooves the minimum.
The grooves will be located as close to the shellside face as possible. As noted above this is to mitigate crevice corrosion problems associated with SS.
All tube holes shall be reamed to size.
All tube ends will be polished prior to assembly of the heat exchanger.
Roll beyond the shellside face using parallel rollers.
All tubes will be seal welded after rolling.
All tubesheets will have 4 vents.
This holds true for all other exchangers except the vents.
On the Ti clad sheets the grooves are in the SS again as close to the shellside face as possible.
RE: Double groove expanded tube to tubesheet joint
You are getting confused
By Sheelside they are talking about the face of the tubesheet where the tubes start and is in contact with the tubeside fluid - not the back side of the tubesheet which is in contact with the shellside fluid
RE: Double groove expanded tube to tubesheet joint
From your reply dated 20 May 08 21:48 hrs, do i know you? pl reply.
Roca- if the other folks impy "shell side" as the face of the tubesheet where the tubes start/end (thereby meaning the face of the tubesheet wetted by the channel side fluid)then you are correct to say that I did get confused regarding the terms used in this discussion.
In my experience, I have always encountered grovves / cladding in the region closer to this face of the tubesheet but never in the region closer to the tubesheet face which is "wetted" by the shell side fluid. In case of cladded tubesheets the detail we typically follow is having 2 grooves in the base metal and one groove in the cladding (the cladding being applied on the face of the tubesheet which is wetted by the channel side fluid).
Hope our understanding matches now. pL correct me in case I am till wrong.
regards,
jehan
RE: Double groove expanded tube to tubesheet joint
RE: Double groove expanded tube to tubesheet joint
BINGO...!
RE: Double groove expanded tube to tubesheet joint
why do you have 4 vents in each tube sheet?
if it is a clad tubesheet please provide a detail
or is it a double tubesheet with a gap between the two to check for leaks?
RE: Double groove expanded tube to tubesheet joint
The 4 vents are located on the compass points and are drilled to just outside the outer line of tubes. By keeping these open while running we are able to prevent the concentration of chlorides and formation of bug condominiums.
On the Ti clad SS tube sheets we have the vents to protect the SS clad base as the life of Ti tubes is more than 10 times that of the SS it replaced.
On the Ti clad tubesheets all groves are in the SS as close to shellside face as possible.