Hi dears

My manager ask me I stimat about stress analysis a petrocamical company. What can A do? It's so important for me.

Thank you

You have asked a very complex question. One that a forum like this may not be able to answer.
However I will offer the following:
Most engineering companies set some minimum analysis criteria on a project by project basis but there is always the exception for even "That" project.
Stress Analysis Criteria may include:
- High Temperature pipe
- Very large diameter pipe
- Very heavy wall pipe
- Very thin wall pipe
- Exotic Alloy Pipe
- Attachment to strain sensitive equipment (Pumps, Glass lined vessels, etc.)
- Extremely low temperature (Cryogenic) systems
- Any pipe installed in Arctic locations
- All other lines below the stated minimum temperature level on a job installed in a place like Oman or Kuwait


To develop an Estimate you need to know the Scope of the Work.
- You need to have a count of the total number of lines in the plant.
- You need to have a breakdown of these lines by categories such as Size, Material, Temperature, Service, Function, etc.
- You need to have a clear idea of which lines do not require Stress Analysis due to size and service
- You need to know the different kinds or levels of "Stress Analysis" there are and the approximate number of hours for each.


Flexibility Analysis might come in a number of forms and should consider many situations.
Forms:
- Simple, Visual Review = Estimate 3 to 5 hours per line
- Intermediate, Informal Calculations = Estimate 8 to 10 hours per line
- Complex, Formal Analysis for excessive stress caused by common factors (Temperature induced expansion, Dead/Live Loads) = Estimate 30 to 40 hours depending on complexity
- Special Analysis (i.e.: Analog studies for reciprocating compressors, seismic studies, Sea-Force studies for Offshore Platforms) Estimate 40 to 60 hours.

Estimated Stress hours include the time to develop any Specifications, Data Sheets and procurement documents for Stress related products such Spring Hangers, Expansion Joints or Struts. It also includes all supervision time, meeting time, any travel to vendors or job sites.

Thank you JOP.

M.M.
Contact me (jopennock@netscape.net) I thought of something else I can share with you.

SURE

THANK YOU

Jop,

I'd like to ask some advices.

Your estimated hours can be fine when you have a pretty large plant.

But I have the following situation:

-small revamping, 20 lines, 450 C

How can I convince my boss that is not the same thing, and that I need more hours than the usual estimated manhours.

Best regards,

I know nothing about where you are, nothing about your company, your piping organization or the individual capabilities of the members of the direct piping staff or the related supporting groups. So it is hard to be very specific.

I question that you have only 20 lines and that all of them are the same maximum operating temperature.

But if you do indeed have only 20 lines and they are all at 450 degrees maximum operating then I you might have the following estimated labor hours for all piping activities.

Category Data Comments
A Number of lines 20
B Estimated number of Isometrics 80

1 Piping Design Hours 1335 (Includes all field trips to determine tie-in points and routing)
2 Piping Material Eng Hours 85 (Assume use existing specs, Review all)
3 Piping Material Control Hours 40 (Depends on how MTO is done)
4 Pipe Stress Hours 150
5 Piping Supervision Hours 90 (Assume working supervisor)

1 Piping Design Hour Percentage 78.5%
2 Piping Material Eng Percentage 5.0%
3 Piping Material Control Percentage 2.4%
4 Pipe Stress Percentage 8.8%
5 Piping Supervision Percentage 5.3%

1 Hours per Line Number 85
2 Hours per Isometric 21.3

Jop,

Thank you very much. I do appreciated.

There are indeed 20 lines and all at 450. This is all I have for this job. A small revamp of an existing plant.

Best regards,

Jop,
You are really excellent in this field.
Up to now, I never meet a specialist who is at same level as you.
Your work is appreciated.

Hope your more posts in this forum.