Snubber in Static Module?

Hello CII Users,

Can we input in static module the snubber. Means it will only act to absorb shock load and not due to thermal load. Or is it in dynamic module only?

Warm Regards,

Snubbers work like regular supports, but they only get "turned on" in occasional cases.

If you have normal thermal growth combined with occasional cases, you have to add a CNODE to the snubber of an otherwise unused node number, and then apply a displacement at that unused node number.

Hi Borzki,

You may employ snubbers in Static stress analysis for the basic/main load cases (e.g. those load cases defined by algebraic combination/summation of individual load components - W, T, P, F, WIN, U), by enabling the corresponding "Snubbers Active" field from Static Load Case Editor definition spreadsheet.

Example:

SUS W+P1 Snubber Active = NO/disabled
OPE W+P1+T1 Snubber Active = NO/disabled
OPE W+P1+T1+F1 Snubber Active = YES/enabled

The 3rd case may represent a PSV/PRV "Pop-Up" case...a "pseudo-static" load case modelling a dynamic action.
Only for this case, the Snubber restraint from CII model becomes active, as "rigid" restraint (such as translation restraint provided as Line-Stop downstream and nearby PSV/PRV).

For all the other preceding "truly" static load cases, the snubber(s) remain(s) inactive and allow the pipe thermal movement (for the OPE case) or the inherent deflection induced by dead-weight and internal pressure (if bourdon effect is activated - for SUS case).

An additional detail:

You may define a finite stiffness for the "XSNB", "YSNB" etc. snubber restraint, and in such case the snubber's actual finite stiffness (e.g. "flexibility") will be considered in analysis.

Thanks Daniel & Michael for that info. That's the info I'm looking for. I'm only familiar using snubber in dynamic module.
Now I can run high temperature lines with snubber acting only to absorb shock load and not thermal load in static module.

Warm Regards,

Borzki,

One "small" errata on my first post:

The loading cases should be defined as follow:

SUS W+P1 Snubber Active = NO/disabled
OPE W+P1+T1 Snubber Active = NO/disabled
OPE W+P1+D1+T1+F1 Snubber Active = YES/enabled

where D1 are the displacements from the preceding "W+P1+T1" case in the snubber node, and evaluated in the preliminary/previous static analysis. These displacements should be specified to the attached CNODE restraint, as Michael pointed out above.

Sorry for this mismatch.

Thanks Daniel for that errata. I will use this info for future reference in case I have a constraint to solve both static and dynamic problem at the same time. In my current case I have managed to use a conventional type of restraint to solve both my thermal load and dynamic slug load by using hold down guide.

Warm Regards,