How to design pressure vessel for 25years life time.

[pjoxygenis]

Hi, I'm new member for this forum, I have some problem for vessel design.
For vessel design life 25years.
What is the important parameter to clarify them?
and how to calculate that parameter?
(sorry my english was bad)

Thank for you kindness

 

[trentar]

specify process conditions in reactor vessel. is it liquid process? any gas?

take care on

material surface corrosion
chemical compatibility in reactor
process pressure
process temperature
friction between fluid in reactor and chemicals in it
process cycles (how many times you plan to heat up cool down reactor
correct welding process for reactor plates

how will you heat reactor?

think about pump life time, supply pipes have valves they also do not have long life time if used frequently, fouling problem in inner and outer side etc,...
safety concern membranes for relief devices, and so on,...
tell us more about process in reactor and you will get data

 

[davefitz]

You first need to select a design code, then review the safety factors that are used in that code's design rules. 2 codes to consider are the asme code and the EN European norm, but other parts of the world have their codes as well. The code with the highest safety factor may provide the most conservative design, but you also need some knowledge of pressure vessel design and failure analysis to complete the chore.

Some codes do not explicitly address corrosion and fatigue damage, and the designer will need to use his experience in addressing these 2 damage mechanisms. Some codes have an explicit creep life limitation ( 100,00 hrs), so you will need to consciously address that in the design stage if a full 25 yr ( 220,000 hrs) is expected.

The vessel or system is only as reliable as its weakest component or section. Locating the part that has the highest stress and/or operates at the highest temperature or which uses a material that is known to be routinely fabricated incorrectly is an important part of the design process, unless you protect yourself using the normal commercial practice of limiting the warranty period to 1 yr. Modern design tools( finite element) can be used to modify the design of particular components such that the stress is reduced to levels similar to that of the rest of the component.

Finally, the specification for the fabrication process , including purchase of materials and the entire QC process , plays a major role in ensuring a long component life.

"Whom the gods would destroy, they first make mad "

 

[weldstan]

Select the correct material with the appropriate corrosion allowance to meet the design conditions referenced above. And then hope that the operators don't operate it beyond the design conditions.

 

[vragle]

You asked a pretty wide-open question with very little to go on.
Extreme operating conditions such as severe cycling conditions or severe temperatures. can affect the life of a vessel, but normally short life is due to improper material to resist corrosion or inadequate corrosion allowance. Knowledge of corrosion is critical to the material selection. Corrosivity may be based on actual field experience or published data, but whatever the source is a primary consideration.

The corrosion affects the material selection. Design conditions (pressure and temperature) and the size (diameter) of the vessel affect the thickness which will vary according the allowable stress of the materials chosen. Material choices may be affected by thickness limitations if you are talking high pressures or large dameters. There is no single parameter that is most important. Each parameter has some effect on every other parameter