Hello All,
I'd like to confirm details of hot reaction force(ASME B31.1 119.10). I understand that we can use the equation 119.10 eq(18) and eq(19) for hot reactions and cold reactions. Also we can calculate hot reaction force by using hot elastic modulus in CAESAR2. And code require the cold modulus to be used in stress calculations. In my view we use the hot modulus with high temperature pipework, when equipment loads or restraint reactions are required and NOT stresses.

Q1. When we need to calculate reactions with high temperature pipe analysis, Could we possibly use the hot elastic modulus option at any restraint? Is there a more specific reference or process about applying hot reactions?

Q2. Basically hot reactions is calculated based on cold elastic modulus and hot elastic modulus ratio. By the way I'd like to inquire about restraint near by turbine nozzle. Pipe line is preheated about 100 celcius for a long time and then rise high temperature. In this case I just same cold elastic modulus and hot elastic modulus ratio. But I was thinking that material property(elastic modulus) will be changed for preheating. I'm wondering if it is correct method or not.

I have very short analysis experience. I hope you give me the advice. If possible, I would like to know and discuss this topic
Thank u for your interest and help.

Using the EH/EC ratio to calculate reduced reactions only works for simple systems.
I would run the operating case twice - once with EC (for the stress range calculation, as in the typical "L1-L2") and a second time using EH for a more accurate calculation of hot reactions.

Hello,

is there any ways to find the Rh and Rc values as specified in B31.1 - 119.10 clause, using CAESAR II.
Also please tell how to relate the same with CAESAR II results.

Regards
Sridhar

any replies...?

Equations (18) & (19) adjust an expansion range calculation and are intended for "simple systems". CAESAR II is considered "comprehensive analysis" where the hot & cold reactions are calculated directly.
I would just run CAESAR II using the appropriate Young's modulus and the adjusted cold spring to set the hot and cold reactions.

thank you Mr.Dave for your response.
I still have following queries,

1. The code does not specify that these equations (18) & (19) are only for "simple systems" and in our model no cold spring is allowed.
2. Also our client still wants to provide the loads as per Clause 119.10 of B31.1.
3. Is it correct to take the loads from CAESAR II,
R = from CAESAR II expansion case
Rh = (Eh/Ec)*R
Rc = -R
C = 0 for no cold spring
dead weight from sustained case of CAESAR II.
all the loads are calculated based on Ec only.

thank you

The reactions in paragraph 119.10 are loads caused by thermal strain. If I wish to mimic these reactions in CAESAR II, I would run a T1 or T1+D1 analysis using the (default) cold modulus. But the system must be linear. This will give R. Then Rh would be as you show but Rc would be 0 (Rc=-CR, with C=0, Rc=0).
CAESAR II provides a comprehensive method of analysis. Using CAESAR II, I would run the operating case using Eh and any cold spring and any nonlinear support. and also run the installed case with Ec. These reactions would also include weight.

The last paragraph in 119.10 implies that (18) & (19) are for simple systems through the sentence "In this case, the piping system shall be analyzed by a comprehensive method."