tie rods, seal and sliding strips???? 2

[shahdadf]

Hi friends,
would you please tell me how i can find the correct nombers of tie rods, seal strips and sliding strips in a heat exchanger without using any software?
thanks a lot

 

[gr2vessels]

I don't believe that you can do that without software (it would be also difficult with the HTRI software unless you are an experienced operator/designer), but you can try using the TEMA, pen and paper. And lots and lots of coffey.

Best chance for you is to get the TEMA and study it first.

Good luck,

gr2vessels

 

[shahdadf]

thanks gr2vessels,
but it can not calculated approximately? only with software?

 

[gr2vessels]

The number of the tie rods and sliding strips can be selected from TEMA section 5, but you still need to know the tubes lay-out to enable you to work out the location of the tie rods and the sliding strips. The sealimg devices, impingement plates or bars, various internal distribution plates are not specified in the TEMA, so you need calculations provided by the HTRI, because of their effect on the heat transfer performance.
Judging by the questions asked, I deduct that your experience with the design of heat exchangers is very limited. Do you intend to design a shell and tube exchanger based on the advices received from this forum? Remember, the forum can only provide some orientative advice and not solutions for your specific work.

Best regards,

gr2vessels

 

[shahdadf]

Dear gr2vessels,
i should check the detail engineeing documents of a consultant company as a supervisor, so i should know somethings about the matters i asked. in some of our basic documents these nombers are mentioned clearly but in other ones no!!! so if i want to check the calculated numbers of tie rods and ....(which our consultant in detail design has calculated) what i shall do???
best regards,

 

[gr2vessels]

I can see your problem and still, not much light at the end of the tunnel.
1. To enable an engineer to check the work of another engineer, the checker should have at least the experience of the design engineer.
2. The Code and the local legislation protects the Buyer of the pressure vessel / exchanger, by forcing the equipment designer / fabricator to accept responsibility for the equipment supplied. In your boots, I would ask the Insurance company, if they are prepare to accept your personal design verification. The alternative is to hire a Third Party Agency for the design verification and fabrication inspection in your behalf. However, you have every right and obligation to check the input data the designer used in his design, for comformance with the purchasing documentation, including datasheets and your specifications.
3. Also, please ask yourself, would you feel confortable to accept and approve the design provided by the exchanger designer, if you could only produce some approximate calculations by hand, in order to check the supplier's software? Would your managers allow you to approve those calculations and drawings?

Best regards,

gr2vessels

 

[doct9960]

shahdaf,

Why do you need to check in "detail" the design documents of your consulting company? Those consulting engineers have their own qualified checkers. As a client yourself, you should just check basic data, schedule & cost. Besides, how can you check designs if you do not know what to check? Checkers should be more knowledgable than the designers. I suggest you read some basic books on heat exchangers & vessels, and then read TEMA and ASME Section VIII. You could also go to training courses.

You also mentioned that you are a supervisor. Don't you have people or specialist under your wings to do your job for you?

 

[jte]

Those consulting engineers have their own qualified checkers.

Optimist. When I started we had checkers. In the mid '90s the checkers disappeared. I've been on the owner/user side for the past several years and very rarely see anyone signing off as "checker" on the calc's which I review. It is not uncommon for me to find errors in the details... not often with ASME code issues (the software *usually* handles this part well) but frequently with custom designed components and with company spec compliance.

jt

 

[thermmech]

True enough, jte.

In the quest to become more "efficient", many fabricators / designers reduced the number of engineers on staff, or simply didn't hire new ones when the senior people retired... when you combine that with the drive to shorten the fabrication times and overall schedules... things get missed, and drawings/calculations go out without a proper check or review.

All this doesn't really help shahdadf.

If the S&T HEx in question is a TEMA design, and owner had specified API 660 and/or some other specifications for the design and fabrication, than he should go through those documents, paragraph by paragraph (including tables on tie rods, baffles, clearances, etc.), make a summary of requirements, and do as much checking as he can.

Ultimate responsibility for the design still rests with the fabricator/designer. Buying heat exchangers without a "detailed" review of drawings was not uncommon in the 80's and early 90's - if the owner didn't have engineers on staff with right skills. Owners would simply list / provide the specifications and data sheets to designers and designers/fabricators had to make sure yourself that exchanger met the requirements.