Expansion loops - When to Use? 1

[John_187]

Hello,

I understand that a linear expansion calculation can be done to determine how much linear expansion has occurred for a certain straight run of pipe.

However, is there a steadfast rule about how much linear expansion on a straight run will require an expansion loop? I have 80 ft of straight run hot water copper type L.

Thanks

 

[PEDARRIN2]

80 feet is not an excessive run for hot water piping as long as it is not rigidly restrained on both ends. Use of clevis hangers and the such will allow for a bit of expansion. Make sure you allow for a bit of expansion, i.e. do not pack your pipe tight.

 

[XL83NL]

Get a copy Markl’s pipe stress book. Though old, and even with current easy and fast (and more accurate) computer methods, it’s basics can still be applied. The flexible length after the first bend always has importance as to how much expansion can be accepted before considering a loop.

The EN13480 code also has a method in one of its annexes to do hand calcs for such phenomena.

Reference to the book from 1953 can be found in this thread

https://www.eng-tips.com/viewthread.cfm?qid=189629.

Make sure to read JohnBreen multi LPS-post!

 

[MJCronin]

https://www.eng-tips.com/viewthread.cfm?qid=392232

https://www.eng-tips.com/viewthread.cfm?qid=197902

MJCronin
Sr. Process Engineer

 

[1503-44]

You need an expansion loop if the straight pipe would overstress or buckle severly if it was fully restrained, or if whatever is restraining that piece of pipe might become damaged from the pipe's applied force if restrained, or the movement of the pipe if it was left unrestrained.

Potential movement increases with both straight length and temperature, but be cautious here as force can be high if the pipe is long or short. Force is independent of pipe length. Force depends directly on temperature increase, no matter if the pipe is long or short, the same force will be developed.

 

[itsmoked]

MJCronin; I tip!

Copy and paste this instead of the URL, for a MUCH clearer link.

thread378-392232

thread378-197902


Keith Cress
kcress -

http://www.flaminsystems.com