Anchor 1

[Orefunto]

Hello and good day to all respected members.

I am new to this excellent forum and I hope the more knowledgeable members don't mind my asking what must be a very basic question.

I've been doing a lot of previous work in Structures, highways, and moved over to pipelines a while back. I started designing HDDs, underground pipes and stress analysis in ASME 31.4 and API 1102 for buried mainline pipes (which generally don't require restraints since they are not on the surface. I'm now tackling surface systems .... now wish to design anchor and guides for a surface system of pipes which will of course require restraints. Generally in my previous designs to ASME, I don't usually need to look up many things as I'm given most parameters including SMYS, e.t.c

I'm aware that there are tables to relate NPS to OD, Wall Thickness /Schedule but I'm not sure if these tables also give the SMYS with the NPS

My question(s) are:
1. Given a pipe of 18 O.D , a Wall Thickness of 0.57" wall thickness and pressure rating of 300#, pls how do I obtain obtain the SMYS? Would this be 300 or do I need to look it up on a table and if so, what table can I use to relate the SMYS to the data given?

2. What code do I need to reference to design the expansion barrels?

3. What codes do I need to design the Anchors and guides?

Your answers will be very much appreciated

Thank you very much....

 

[CRG]

Do you have a copy of ASME B31.4?
Have you read the code?
For the 2009 Revision,look at table 403.2.1-1 for SMYS.

 

[Orefunto]

Thanks for your response CRG.
I don't have the complete code (31.4), I only extracted the portions I had been using in the past to respect copy right issues. I will have to obtain the complete code since I'm now doing more of stress analysis and piping. I've been a generalist doing so many other things, but it looks like I will be focusing on this now

I imagined the 31.3 would have its own tables which would be different from the tables in 31.4.

Please is there a typical spacing for anchors? And if I wanted to calculate the frictional forces, would I have to take the weight of the entire pipe between anchors?

I'm also wondering if I need to look up the catalogue of expansion join manufacturers to obtain forces necessary to deflect their expansion joints or if there are values in the ASMEs.
I obviously have a lot of reading to do

Sorry for the bother...

 

[Orefunto]

I should provide more clarification.
Its an 18" line , .57 WT, with design pressure of about 550 psi to operate with temperature changes of about -40 to 40 degrees.

I'm thinking of trying as a start,anchoring about 250 meters(800 Ft approx) intervals with guides in between, calculating the forces on this arrangement and adjusting if need be.

Does this sound reasonable?

Thanks again..

 

[CRG]

No, it does not sound reasonable to use expansion joints on a B31.4 pipeline unless it is underground in a utilidor. For above grade pipelines, consider expansion loops instead of expansion joints. If it is in a utilidor with limited space, then expansion joints may be a necessary evil. I suggest that you get some help with this. Also, expansion joint anchor loads are dependent on a lot of factor. Such as, where valves are located, location of bends, seismic loads, how the system might be isolated in the future, etc. Take a look at

http://www.metraflex.com/pdf/Metraflex_MetraGator.pdf

for a sample calculation; however, there is not enough info there to design a system. It really sounds like you need a mentor to help with this project; especially if there are any consequences from a failure.

 

[CRG]

More reasons why expansion joints might be a bad idea and why you may want to consider expansion loops. Some anchors will see loading from pressure around 200,000 to 250,000 lbs if you use expansion joints (note this varies depending on the manufacturer's effective area). Your loads go up significantly depending how you hydro-test the line. Also, don't ignore seismic loads on top of pressure loads for some of the anchors.

 

[Orefunto]

Thank you CRG,
I meant expansion joints for the above grade pipeline because of space constraints.

I did some calculations taking into consideration natural flexibility and observed that the offset lengths between anchors locations I was thinking about were just not sufficient, that was why I mentioned expansion joints.

Also, I'm not working on this alone, I'm just doing some very preliminary calculations for now and doing my homework along.

 

[Orefunto]

I should mention that I agree that the loading will go up with the expansion joint, but I was thinking of not the unrestrained axial expansion joint that would introduce thrust pressures that would have to be compensated for.

I was thinking more of the other types like the fully articulated ones which eliminate thrust pressures because they are restrained

 

[BigInch]

NO expansion joints. You should not need them. The temperatures are not excessive and its a pipeline, outside the pump station and away from critical equipment. Even in the pump station, temperatures are low enough that you should not use one single expansion joint. Extra wall thickness will pay for itself in no maintenance and no shutdowns needed to fix the joints.

Expansion joints should only be used inside stations where there is constant inspection and easy maintenance possibility AND there is expensive, critical equipment that cannot be protected any other way.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus

 

[Orefunto]

Sorry for the bad job of explaining.

I kind of realize expansion joints come in various shapes and forms and that the axial ones are not desirable. So I indeed relied first on natural flexibility as CRG mentioned. I calculated the required loop or offset and when this is not sufficient, I was wondering what the solution would be. Perhaps my use of terminology was wrong but what would be the difference between slip joints , expansion barrels and other expansion containing devices?

It would be nice if there was a kind of rough guide for spacing of anchors and guides but I realize this would be based on the forces one is willing to design and put up with on the anchors and guides