Topic Options
#74001 - 10/23/19 06:56 AM Seismic analysis for pig launcher and underground pipes.
zall Offline
Member

Registered: 11/15/18
Posts: 11
Loc: Turkey
Hello dear experienced people.
I have a question about a pig launcher station. Firstly pipeline comes to launcher from underground and connecting to launcher. After again it goes into the soil. In such a stiuation how do i seismic analysis? Because i have read in other topics that seismic analyse for underground pipes does not true. And also there are different max and min temperatures for aboveground and underground. How do i perfom analysis for difference max and min temperatures.


Attachments
a1.png

a2.png

a3.png



Top
#74007 - 10/23/19 10:06 AM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
mariog Offline
Member

Registered: 09/29/07
Posts: 683
Loc: Romania
First, you need to model enough underground routing in order your model get- at UG/AG points -the appropriate figures as displacement under pressure and UG temperature. Doing in this way, the AG part will see that imposed displacement, but also temperature, pressure and inertial seismic as you define in your model.

In case your concern about seismic is the UG part, CII is not a tool to evaluate this subject because the inertial forces are not really of interest for UG.

Top
#74012 - 10/23/19 11:12 PM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
zall Offline
Member

Registered: 11/15/18
Posts: 11
Loc: Turkey
I think just modelling of above ground part is not sense. But when i define the uniform seismic force the force was defined whole pipeline.


Edited by zall (10/23/19 11:15 PM)

Top
#74013 - 10/23/19 11:13 PM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
zall Offline
Member

Registered: 11/15/18
Posts: 11
Loc: Turkey
Originally Posted By: zall
Hello dear experienced people.
I have a question about a pig launcher station. Firstly pipeline comes to launcher from underground and connecting to launcher. After again it goes into the soil. In such a stiuation how do i seismic analysis? Because i have read in other topics that seismic analyse for underground pipes does not true. And also there are different max and min temperatures for aboveground and underground. How do i perfom analysis for difference max and min temperatures.
I think just modelling of above ground part is not sense. But when i define the uniform seismic force the force was defined whole pipeline.

Top
#74019 - 10/24/19 11:38 PM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
mariog Offline
Member

Registered: 09/29/07
Posts: 683
Loc: Romania
I'm not sure I understand your replay.

You need to model underground part but don't expect the seismic calculation is relevant for that part.

You need to model underground part because this part is relevant for displacements (I mean non-seismic displacements) imposed to the above ground part. This will solve also your concerns about temperature applicable for UG vs AG.

Top
#74023 - 10/25/19 11:15 AM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 816
Loc: Louisiana, US
In the majority of cases, in reality, seismic loads are not a concern for underground piping. It is universally supported. There's no way for it to bend underground.

If you have thin pipe, I guess you could have the pipe ovalize due to weight of soil, and then attempt to de-ovalize due to sudden momentum... but that's not a CAESAR problem.

If you were to apply a uniform load to caesar's model of underground piping will mean that between each spring support, the pipe will appear to "sag" between supports, except in the horizontal plane, which does not reflect reality.

The reality is all of your underground piping, as well as the buried portions of your pipe supports, will suddenly displace X in/cm in Ts, and your above ground piping and supports won't due to their inertia. You can simulate this statically as though the ground were stationary and a force is applied to the pipes in the opposite direction. You could also simulate this dynamically as a displacement of all the underground piping, supports at the bases, etc.

Top
#74051 - 10/30/19 08:54 PM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
Arjun_Unniyampath Offline
Member

Registered: 10/19/13
Posts: 4
Loc: India
You can also turn off the uniform load at the AG/UG interphase if that is your concern.
_________________________
♫♪ XVI ♫♪

Top
#74073 - 11/04/19 07:32 AM Re: Seismic analysis for pig launcher and underground pipes. [Re: Arjun_Unniyampath]
zall Offline
Member

Registered: 11/15/18
Posts: 11
Loc: Turkey
Originally Posted By: Arjun_Unniyampath
You can also turn off the uniform load at the AG/UG interphase if that is your concern.


Sorry how can i do this?

Top
#74075 - 11/04/19 10:32 AM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
Michael_Fletcher Offline
Member

Registered: 01/29/10
Posts: 816
Loc: Louisiana, US
When you specify a uniform load vector, it carries forward. You can specify a new uniform load vector of 0. (Or off. To be honest, it's been a while since I've used it.)

Top
#74132 - 11/12/19 03:06 AM Re: Seismic analysis for pig launcher and underground pipes. [Re: zall]
sharu Offline
Member

Registered: 04/09/13
Posts: 21
Loc: india
For Disabling Sesimic condition in Underground piping, define a new "Uniform Load" in CAESAR and enter Zero in all applicable fileds. Make sure to enter correct values when the pipe model comes above ground by clicking "Uniform Load" once again.

For buried piping portion, as per my previous experience, minimum temperature shall be considered as ambient temperature only.

Regards,
_________________________
sharun

Top



Moderator:  Dave Diehl, Richard Ay 
Who's Online
0 registered (), 66 Guests and 1 Spider online.
Key: Admin, Global Mod, Mod
December
Su M Tu W Th F Sa
1 2 3 4 5 6 7
8 9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31
Forum Stats
11721 Members
14 Forums
16089 Topics
72133 Posts

Max Online: 191 @ 11/16/19 10:39 AM
Top Posters (30 Days)
Michael_Fletcher 23
Sigma 13
vermaccio 12
Faizal K 8
Vanman 7