63,000# Axial Stop

[StressGuy]

Just had the latest Piping Tech (PTP) newsletter hit my inbox. Their showing a cold shoe/axial stop designed to withstand a 63,000 lb axial load.

http://www.pipingtech.com/

I must confess, I've not worked LNG. However, I see something like that, and my first thought is that there must be a mistake somewhere. Dealing with a load like that would most likely generate much wailing and gnashing of teeth with our structural engineers and I'd be concerned about what's taking all the equal and opposite reaction.

So, for my own education, is something like this common in LNG?




Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[JohnBreen]

Hi Ed,

Thank you for posting the subject for discussion. Of course I know that you know better but how many inexperienced piping engineers will accept that "capability" without due consideration. you have done a great service to bring that to the table. So let me just say:

OMG!!!!!! SIXTY THREE THOUSAND POUNDS of axial loading!!!!!!

I would make reference to the B31 Code Case 178, May 6, 2005, "Providing an Equation for Longitudinal Stress for Sustained Loads in ASME B31.3 Construction"

An important term in that equations is Am / Fa. But that is only one thing that needs to be considered. Axial instability (slenderness ratio) and buckling are also to be considered.

Hey kids, don't try this at home.

Regards, John.

 

[xhpipe]

what size line is the stop rated for 6"NPS????

Regards,
XHPIPE

 

[racookpe1978]

It's insulated, 36" dia, apparently supporting the 63K (axial ?) load through the insulated aprt of the restraint.

Maybe for a vertical pressure vessel 36" in dia?

I would certainly not expect a "pipe" to require 36K of in-line load.

 

[Zapster]

All it takes is for an engineer or owner to decide that an expansion loop would take up too much room and decide on an expansion joint in a run. Axial forces can be huge for modest pressures as pipe diameters go up when expansion joints are used.

 

[JohnBreen]

Hello all,

By the way:

It was not my intention to reflect negatively on anyone that is supplying hardware and equipment. Quite the contrary, I only wanted to "wave a flag" to those who might not consider all the issues before properly using such equipment.

Regards, John.

 

[BigInch]

Sorry to take the wind out of the sails, but 63 kips is not very much for pipelines. When you get a 36" diameter 0.5 wall operating at 190F entering a pump station, it takes something more like a wall on the Titanic's dry dock to (try to) hold it in place.

http://virtualpipeline.spaces.msn.com