×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Tube to Tubesheet Joint in Claded surface

Tube to Tubesheet Joint in Claded surface

Tube to Tubesheet Joint in Claded surface

(OP)
Hi All,

We have a tubesheet which has a clad on tubeside but not on shell side.

According to specifiaction we require two grooves expaned tube to tubesheet joint. My doubt is where the grooves to be located.

As per my understanding one groove on clad (to avoid corrosion ) and other on base material but TEMA and API say (or do not recommend)no groove on clad portion. How to proceed please explain.


Regards,
KR

RE: Tube to Tubesheet Joint in Claded surface

Usually, I put both grooves in the base metal only. Some customer specifications ask to put a third groove in the clad portion but this is definitely not the norm. Also, it would require a thicker cladding (about 1/2" thk) in order to accommodate the groove.

I tend to include seal welding, if possible, when I use weld overlayed or clad tubesheets to prevent corrosion. The ability to do this of course depends on your material of construction.

RE: Tube to Tubesheet Joint in Claded surface

(OP)
Afox88,

Thanks for the response i can understand we can provide a seal weld or strength weld or include groove in clad to prevent corrosion, but why does the API or TEMA does not specifically talk about that, our problem is the vendor has started to debate on the consideratinon of API and TEMA and requesting for extra price for performing a seal weld.


Regards,
KR

RE: Tube to Tubesheet Joint in Claded surface

TEMA RB-7.44 specifically says "all grooves should be in the base material unless otherwise specified by purchaser", presumably because cladding is generally not used as a load-bearing material.

I would double-groove the base material and then seal weld the tube-to-tubesheet joints to prevent crevice corrosion.

-Christine

RE: Tube to Tubesheet Joint in Claded surface

(OP)
Thanks Christine, for your suggestion.

Regards,
KR

RE: Tube to Tubesheet Joint in Claded surface

Out of curiosity what is the base metal and what is the clad MOC in your case? Also, what are the thicknesses.

RE: Tube to Tubesheet Joint in Claded surface

(OP)
Base metal is SA-266 Gr.2 weld overlay Ni-Alloy and tubes are SA-268 TP405

Regards,
KR

RE: Tube to Tubesheet Joint in Claded surface

And people still use grooves.
They only work (help) when the tubesheet is much stronger than the tubes.
If the strengths are close, or the tubes are stronger, or the tubes are very thick, then a series (5-15) of small shallow "vee" grooves help much more with joint strength and sealing.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Tube to Tubesheet Joint in Claded surface

TEMA and API specifically prohibit any grooving in the clad portion.
However, you may need to consider the fact that Codes always stipulate only the bare minimum requirements, and the actual technical requirements are specified by the End user in the form of Project specifications.

Did you check the applicable Project specifications?
Has the Client specifically requested that Clad tubesheets be provided with seal welded joints in order to avoid crevice corrosion?
If no, you may just go ahaead with grooves in the base metal and expanded joints...
I think the Vendor is quite justified in asking for a price adder for seal welding since this is a big, unforeseen additional chunk of work for him to seal weld all the joints.

RE: Tube to Tubesheet Joint in Claded surface

API 660: For shell-side-clad tubesheets, the tube shall be expanded to seal against the cladding material for a
minimum distance of 6 mm (1/4 in).
See more in API 660
Regards
r6155

RE: Tube to Tubesheet Joint in Claded surface

r6155,
The Exchanger under discussion is cladded on tubeside only, not on shell side.

RE: Tube to Tubesheet Joint in Claded surface

chevproe, you say "TEMA and API specifically prohibit any grooving in the clad portion", but API 660 only shell-side is mentioned, hence for tube-side nothing prohibit.

Regards
r6155

RE: Tube to Tubesheet Joint in Claded surface

chevproe, you say "TEMA and API specifically prohibit any grooving in the clad portion", but API 660 only shell-side is mentioned, hence for tube-side nothing prohibit.

Regards
r6155

RE: Tube to Tubesheet Joint in Claded surface

r6155,
Did you check API 660(9th Ed.),Par. 9.10.5??

Quote (For tube side clad (or weld overlay) tubesheets with either strength-welded or seal-welded and expanded tube-to-tubesheet joints, tube hole grooves, when provided, shall be located in the base material and not in the applied cladding or weld overlay)


RE: Tube to Tubesheet Joint in Claded surface

chevproe
Sorry, I have only historical version 8th ed 2007 par 9.10.4. Most recent is 9th Ed 2015 not in my hands.

Regards
r6155

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources