Thanks for your reply to the above topic by Mr.ianpinoy and Mr. John Breen.
I need some more clarification in the above topic itself. I have given my new message along with my earlier message as follows.

New message
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Subject : To carry out Flexibility and Stress Analysis as per ASME B31.3 (2004),

Where Fluid : Crude oil pipeline carrying oil from manifold to tank.
Design temperature = +93°C
Solar radiation metal
black body temperature = +85°C (as furnished for un-insulated above ground piping)
Service / Operating temperature = +60°C
Installation Temperature = 21.1°C
Winter minimum dry bulb temperature = minus 3°C
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Please note that in Piping Handbook (Mc Graw Hill publications Sixth Edition) by M.L.Nayyar. topic Design bases / Design temperature page B.41 it is written that,

"The normal operating temperature is used as the basis for all thermal design analyses that relate to the structural integrity of the piping system, including the thermal flexibility analysis, the spring hanger sizing and setting calculations, and the thermally induced anchor movement calculations. Pressure integrity design is based on design temperature”.
In our case normal operating temperature is +60°C.
In pressure vessel design hand book by Henry H. Bednar it is written that “design temperature is the maximum temperature of operating fluid plus 50°F as a safety margin. It is also written that secondary stress is self-limiting and self equilibrating. It has also mentioned that for secondary stresses use operating loads.”

Even though we understood yours reply, our reviewing authority wants to know
for thermal loading condition whether to take 21.1°C to 60°C or 21.1°C to 85°C. or some other combinations.

Old message
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We have a CASE to be studied as follows:

1. An un-insulated piping system connected to equipment having service temperature of maximum + 60°C.
2. Piping system is exposed to atmospheric condition as the system is un-insulated, above ground and outdoor installation.
3. Black body metal temperature due to solar radiation is predicted to be maximum +85°C as per furnished data.
4. Winter minimum dry bulb temperature minus 3°C.
5. Climatological data.

Month mean mean monthly Daily
daily daily mean variation
max °c min°c °c °c
January 18.4 7.9 13.1 10.5
February21.0 8.6 14.9 12.4
March 25.6 13.3 19.5 12.3
April 32.2 19.0 25.6 13.2
May 38.2 24.6 31.7 13.6
June 44.0 27.6 36.4 16.4
July 45.6 29.6 38.2 16.0
August 45.2 28.4 37.3 16.8
September41.5 24.9 33.7 16.6
October 35.5 20.6 28.1 14.9
November26.5 15.0 20.7 11.5
December20.0 8.3 14.0 11.7

6. What temperature load conditions are to be analyzed? Is it

i. 21.1°C to 60°C
(or)
ii. 21.1°C to 85°C
(or)
iii. 21.1°C to minus 3°C
(or)
iv. minus 3°C to 85°C
(or)
v. Any other combination and / or range of temperature condition.

We will request your views on URGENT basis.

Regards,
P. Manivannan.
Piping design engineer,
Heavy Engineering Industries and Ship Building Company (HEISCO),
KUWAIT.
Email:psmani@heisco.com

Hello Manivannan,

I understand your concern but on actuaal condition, your piping is exposed to solar heat which is 85C, higher than your operation temp. At a certain season at your location piping expansion of your pipe is different from that of your normal operation condition.

But if you are having doubt to this things, much better to check it on both conditions.

Best regards,
ian

The use of the "Design" as it relates to temperature sets off an alarm bell with me. B31 1/3 use the word design in conjuction with the words temperature and pressure soley as it relates to pressure wall thickness or pressure rating.

As far as displacement analysis is concerned the system should be evaluated for the maximum and minimum operating temperatures. The stress range which is the strain between the two extremes must be accounted for.

In order to account for the range one subtracts one operating case from another....

Your worry here is temperature,
I am assuming you have long runs for this to be a concern, but here goes.

An empty pipe is probably your worst case, as a fluid filled piped has alot of thermal inertia.
Therefore you will have the pipe empty on a cold day, and the pipe empty on a hot day.
So, use 21 to 85c (worst hot case)
And 21 to 3c (worst cold case)

Take one from the other to find range.

I would speak to the process engineer to talk about that operating temperature, it could well be the OP temperature is a guess and that analysis is not required,
I would include seasonal temperatures on exposed pipework if analysis is required for OP temperatures
But pipework would not normally be stressed just for these environmental factors (there are lots of excemptions here)

I'd be suprised unless you have long runs, that these temperatures will be problematic.

You will not find all the answers in a book and it would be good to shoot the breeze with other experianced engineers when coming up against problems such as this. ( this forum especially)

Hello Manivannan,

AGAIN - What piping Code are you designing the system to?

The stresses due to sustained weight and pressure are primary stresses. The stresses due to thermal expansion/contraction (aka displacement stresses) ARE secondary stresses. Previously on this board there have been many discussions of primary and secondary stresses and I would suggest that you use the search function here to review those discussions. Let us consider secondary stresses.

What is the coldest possible temperature that the pipe metal could be at any time after the system is installed? Is it your engineering judgment that the coldest pipe metal temperature will be minus 3 degrees C. ???

What is the hottest possible temperature that the pipe metal could be at any time after the system is installed? Is it your engineering judgment that the hottest pipe metal temperature will be 85 degrees C. ???

The B31 method of evaluating (secondary) thermal expansion/contraction (displacement) stresses addresses the fatigue that can result from cycling (alternating) loadings caused by many thermal excursions from ambient (installed) temperature to the coldest temperature and from ambient (installed) temperature to the hottest temperature. The B31 method of evaluating (secondary) thermal expansion/contraction (displacement) stresses is to evaluate the "stress range" that results when you add the strains due to contraction (from ambient temperature to the coldest possible pipe metal temperature)to the strains due to expansion (from ambient temperature to the hottest possible pipe metal temperature). This "stress range" will be unsigned (neither plus or minus). An example:

Hottest temperature - 85 degrees C.
The temperature excursion (delta T) from 21.1 degrees up to 85 degrees is 63.9 degrees C.

Coldest temperature - minus 3.0 degrees C.
The temperature excursion (delta T) from 21.1 degrees down to -3.0 degrees is -24.1 degrees C.

Temperature difference between -3.0 degrees C. and 85 degrees C. is 88.0 degrees C. (the absolute value of -24.1 degrees added to the absolute value of 63.9 degrees is 88.0 degrees). For your displacement (expansion/contraction) stress range analysis, you are interested in evaluating the piping for the total 88.0 degree C. temperature excursion. ONE WAY (there are other ways) of doing this is to allow Caesar II to assume the (default) ambient temperature is 21.1 degrees C. and use an operating temperature of 109.1 degrees C. (21.1 degrees plus 88.0 degrees (total temperature excursion) equals 109.1 degrees). This analysis will calculate the (thermal expansion/contraction (displacement) stress range for a thermal excursion of 88.0 degrees. But the loadings on the boundary elements (supports, equipment) will not be correct.

All the other thermal excursions (with delta T's of less magnitude that the excursion described above) will be "partial cycles". These partial cycles are addressed by "adjusting" the factor "f" in the B31 Code equation for calculating the maximum allowable stress range (Sa).

Regards, John.