Previous in Forum: Seal   Next in Forum: Square Ball Transforms U-Joint
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
8 comments
Rate Comments: Nested
Attyub194
Participant

Join Date: Aug 2018
Posts: 3

Repair of Tubesheet for TEMA R Tube Sheet

08/06/2018 12:19 PM

Dear All,

TEMA does not specify the criteria and is silent on repair procedure if the drilled holes in new tube sheet exceed the limits specified in TEMA RCB 7.21
Please suggest that in case the drilled holes are more than the limits specified in TEMA what would be the remedy if the drilled holes exceeding the maximum limits specified in TEMA and exceeds 10% of the tube count and on the other hand if the drilled holes are more than the limits specified in TEMA what would be the remedy if the drilled holes exceeding the maximum limits specified in TEMA and is less than 10% of the tube count.

As per my own understanding, ASSME VIII is also silent for specifying the criteria of acceptance or rejection of newly drilled tube sheet if the drilled hole dia are exceeding the TEMA limits.

Could someone share the experience what normally exchanger manufacturer do in this case or what are the general practice adopted by Tubesheet drilling companies.
This is a common issue and there are normally results in long debates between Purchaser and Manufacturer and finally, it is a compromise due to cost and time involved.

Also, NBIC is silent on the acceptance and rejection criteria as well whereas on repair procedure (NBIC part III covers some methodology for tube sheet(S 1.2.11.6 )however, it is somewhat more generalized and do not cover how tubesheet bulging would be avoided.

also, the cost of new tube sheet is a major factor. Such acceptance/rejection criteria is even not available in API standards.

Normally, in such cases third-party inspectors recommend to plug the tube sheet holes, provided the thermal performance is acceptable to purchaser.

Could any suggest any solution or info which could lead to simplicity and suggest a repair procedure acceptable in light of code and standard with reference?

Best regards
Ahmed Attyub
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#1

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/06/2018 5:16 PM

This sounds like an issue to be worked out between the purchaser and the manufacturer, and the design engineer...If your supplier can't meet specs, it's time to shop around...

http://www.heatexchange.org/pdf/techsheets/TechSheet106.pdf

http://www.tema.org/inquiries/

__________________
 All living things seek to control their own destiny....this is the purpose of life
Register to Reply
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#2
In reply to #1

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/06/2018 7:20 PM

https://www.practicalmachinist.com/vb/antique-machinery-and-history/retubing-small-fire-tube-boiler-329105/

http://www.industrialboiler.com/Services/Boiler-Repair/Boiler-Retubing

__________________
 All living things seek to control their own destiny....this is the purpose of life
Register to Reply Score 1 for Good Answer
Go to Next "Almost" Good Answer
Tornado
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#3

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/06/2018 7:52 PM

Where is all this taking place--Elbonia??

__________________
 In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
Anonymous Poster #1
#4

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/06/2018 8:54 PM

Are tubes welded or rolled to tube sheet?
Register to Reply
Attyub194
Participant

Join Date: Aug 2018
Posts: 3
#6
In reply to #4

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/10/2018 12:55 PM

Dear Sir,

It is Strength Welded
Register to Reply
2
RAMConsult
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3230
Good Answers: 444
#5

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/07/2018 12:05 AM

It sounds like you are trying circumvent the clearly stated limit on the number of oversized holes. I hope that you're not looking for "repair procedures", such as bushings or resizing the hole by welding filler material in and redrilling to the correct size, to compensate for the poor fit between some of the tubes and the tubesheet. Such methods are unsafe and generally not allowed. Basically it's "too many oversized holes, no good. Too many undersized (but still within spec) holes, no problem"

There is a simple solution, insist on seeing the QA results of other customers' purchases, and find a different vendor if you don't like the results.

__________________
 “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply Good Answer (Score 2)
No more Good Answers. Go to first "Almost" Good Answer
Attyub194
Participant

Join Date: Aug 2018
Posts: 3
#7
In reply to #5

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/10/2018 1:10 PM

I would like to mention that this happen while drilling by a local heat exchanger manufacturer while manufacturing new heat exchanger.

It is established fact that the 15 % holes are over drilled beyond the limits defined in TEMA.

We insisted on providing new tube sheet but the manufacturer donot agree as there is no acceptance and rejection criteria defined either in ASME VIII or TEMA . The are insisting on extended warrantee and possible repair.

We do not find any repair methodolgy permitted by the code for filling the complete hole by welding and re-drilling and methodology to avoid tube bulging due to heat input

Additionally, purchasing a new tube sheet and re drilling is a 3-4 month activity

and we are still stuck up for the solution
Register to Reply
RAMConsult
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3230
Good Answers: 444
#8
In reply to #7

Re: Repair of Tubesheet for TEMA R Tube Sheet

08/12/2018 5:43 PM

You're right, it is usually disallowed by most codes because it dangerous, therefore you will not find any legal fix. The reason for this is already known to you, since as you said "...to avoid tube bulging due to heat input..."

Some of the problems in addition to your own observation, are: metallurgical changes in the tube sheet which lead to stress cracking, non-uniform bedding material for the seal-welding (welding on welding instead of welding on base-metal), lack of proper welding post heat treatment, the possibility of out-of-round "repaired" holes which in turn leads to non-uniform contact between tube and sheet, etc., etc.

Your QA "team" should be looking into why you have so many off-spec holes, and how to prevent that and other defects in the future, instead of trying to find illegal and dangerous methods of supposedly repairing the aftermath of your poor manufacturing procedures.

__________________
 “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply Score 1 for Good Answer
No more "Almost" Good Answers.
Register to Reply
Have a Different Question?
8 comments

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Anonymous Poster (1); Attyub194 (2); RAMConsult (2); SolarEagle (2); Tornado (1)

Previous in Forum: Seal   Next in Forum: Square Ball Transforms U-Joint

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Mechanical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (63 right now)
Show Members
Advertisement