time estimation for vessel design 1

[farzam]

Dear All,

please let me know, what requirements must be considered to make estimation of time to design of a vessel.

Thanks in advance

 

[corus]

It's best if you have designed one before then you will know, roughly, how long it took you. These days there is software available that can let you design a vessel to the relevant design code very quickly. Otherwise the question is very similar to 'how long is a piece of string'.

corus

 

[gerhardl]

It will depend on resources/personnel available, quality of their experience, complexity of vessel, and if the vessel is a copy of something done before or a complete new design.

The answer : from very little to very much time.

What are you actually trying to do? Argue a too high bill received, negotiating, make a time schedule or buy?

Try to reformulate your question, and you would have a far better chance of getting a more useful answer.

 

[CodeRef]

corus,
GREAT! analogy stating 'how long is a piece of string' I had to laugh.....reminded me of a note marked on a stool I saw once.
Here is what it read... FOR SOME, IT'S JUST A STEP UP. FOR OTHERS, IT'S A CLIMB.

 

[Duker37]

I have to agree with "gerhardl". However, I have been designing pressure vessels for some time now and bascially I look at things like: pressure, temperature, diameter, overall lenght, how the vessel is to be support, what is being attached to the vessel (plateforms & pipe support clips, ect...) and how thick the design specificiations are before I can get a good feel for how long it will take me to design it. Basically, it would take me less than 1 hour to design (using a basic pressure vessel design software) a pressure vessel less than 14' in diameter, about 20' tall, design pressure less than 300psig, design temperature less than 500deg F, no attachments like plateforms and pipe support clips, supported either on 2 saddles or skirt/legs, going to a site where I have all the necessary information for wind/seismic codes and not to many nozzles. I hope this helps.

 

[Ganfoss2]

You have selected the wrong way to outline your problem!

It dependeds on a lot of factors:

If you have to design simple drum (like in the Appendix L of ASME VIII-1), a Shell & Tube Heat Exchanger (you have to include even the Time spent for teh Thermal Rating of teh Equipment), a Reactor, a Column or ... a Burried Tank of a Classical Tank!

If the Equipment has a lot internals or not (Check for Interferences and/or Reaction Loads on Equipment's Wall).

If it has Axusilary Structures = External Cages / Ladders / Platforms or not.

If you have all the Basic Informations and/or requirements since the beginning of the Project or not.

If your Client want to comments your Design (and Detail/ G.A. Drawings) or not.

If your Procurament Office has problems on the Material Supply or not (Delivery Time and/or Material Certification and/or Mechanical Properties).

If your Workshop have problems or not.

If you have all the necessary SOFTWARE to allow a proper design since the beginning or not (FEA, WRC107/297, Wind/Earthquake Evaluation).

If you are confident on the Requirements stated in the Code or if it is the first time you apply its roules or not.

If your Client ..... know what he want or not !!!!

Take in account that YOU HAVE TO ISSUE the Construction DWGs that should reflect your Design and you have also to check many times if teh Code Requirements have been mplemented or not in the Construction Details (with the Code Calculation only ... you cant go more "far"!)

Too many variables!

I worked for an Engineering Company and also for a Manufacturer Company. Too diferent and not compatible worlds!

What I have stated before is valid for a Construction Company. For an Engineering Company with the DESIGN and FOLLOW UP generally the "budget" time vary from 50h (for single item) for SIMPLY ITEMS (Drums) up to 180h (for single item) for Complex Items with a lot of internals to be checked.

These time include: SEMPLIFIED Calculations to get the thickess of cylindrical shells, shell transitions and formed heads, taking in account the Int/Ext. Pressure, the Reaction Load at Supports, the Wind/Earthquake Loads to get the Foundation Loads. It also take in account the time necessary to review each Vmanufacturer Documents.

The fromer activity take generally 1/3 while the latter tale 2/3.

But keep in mind that this activity is not paragonable to the activity perfomed inside a Manufacturer Company!!!!!!

Time spent for a Design in a Manufacturer Company if .. peanuts! The major costs come out from the Material Supply and for Workshop Manufacturings & Inspections. Engineering Costs generally are 10%-15% of the Equipment Costs (even if you take lafy time!).

 

[djack77494]

Time to design is dwarfed by the time to check, clarify, modify, and redesign (repeatedly).