Bases and criteria for deciding whether or not to use an anchor block in a pipeline 1

[brvs2014]

Develop the analysis of flexibility of a Pipeline however I am not clear with which criterion to use or not to use an anchor block, is there in any norm a backup to use or not anchor blocks ??

I appreciate your help

 

[bimr]

Maybe a start would be describing the scope of your project. Is it 10 mm plastic tubing, a 6' diameter sea water intake, or a 3,000 mile 36" crude pipeline?

 

[brvs2014]

PipeLine is API 5L x42 Long:2.48549 Mile Crude Service, Aerial and buried.

 

[mk3223]

The anchor block design may be depended on the soil condition and how much the flow serge load inside the pipeline you have.

 

[BigInch]

Anchor blocks generally convert pipe axial expansion or contraction into compressive, or tensile stress, respectively. Using an anchor block thereby will increase pipeline stress. That is not something you should do without a good reason. When should you then use an anchor block, or a pipe stop? You should use anchor blocks, or pipe stops only when the expansion or contraction of a pipe would cause damage to the pipe itself, or to the equipment attached to it. Keep in mind that the expansion or contraction of a pipe is not usually what causes damage. Free expansion or contraction does not result in pipe stress. Damage is caused by trying to limit that expansion, or contraction. Limiting expansion, or contraction of a pipe is typically caused by the anchorage of attached equipment, friction of the pipe on its support, by soil "sticking to" or otherwise prohibiting movement of the pipe and by connections to other pipes. Limiting movement at one point of a pipe will tend to force the movement to more flexible regions of the pipe configuration. If flexible regions of the pipe configuration are favorable, some reduction of stress is usually accomplished if the pipe can freely expand into that region. At times stress in other regions may become worse, for example, if the pipe is partially restrained and works against restraining ,and worse yet, leveraged, pivot points.

With those set of guidelines, you can develop a few general set of rules for anchoring pipe.
1.) Don't do it unless you need to.
2.) You only need to do introduce restraints when stresses from already holding the pipe from moving are too high for the pipe itself, or for the attached equipment.

Where should you use anchors? You should use anchors only in places that will force the pipe to move towards other reqions of the pipe configuration that are flexible, areas where such movement will not be accompanied by increased stress, preferably at any point in the pipeline.

To do your job as a "pipe flexibility engineer" correctly, you should not be asking questions about how to add anchors and thereby seek to increase stresses. You should be reducing stresses. Therefore look to add FLEXIBILITY, not anchors. That is the question that you should be asking, "How do I increase flexibility the of this piping system?"

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[LittleInch]

I was waiting for BI - agree with all that.

The norm - don't use them.
Reality is that unfortunately piping engineers like working away from fixed points and this horrible flexible unknown thing called a pipeline or flowline disrupts their nice neat way of thinking, so sometimes despite all arguments to the contrary, you end up with one.

It doesn't help that when modeling the buried sections, people often leave the connection end as a "free end" and hence report large amounts of displacements which the piping designers throw their arms up in horror at, but are normally quite unrealistic once you add on the weight and strength of the attached piping. The only way to properly design any system is to do it as a single pipe / system which just happens to be buried for some sections.

You don't say pipe size, pressure or range of temperature, which is usually the key issue, but design in flexibility, especially at the connection between pipeline / flowline and piping and the desire to pour large quantities of concrete into the ground tend to go away....

The only one you need to really worry about is where you have buried tees, especially small bore one close to the end where a pipe can move. The you might need to do something which avoids the shear and bending on the connection.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[DSB123]

brvs2014,
You say "PipeLine is API 5L x42 Long:2.48549 Mile Crude Service, Aerial and buried."

By "Aerial" do you mean in the air? If so then I do not think you can place Anchors on the Aerial sections unless the supports are "sky hooks".

 

[LittleInch]

"Aerial" in some places just means above ground on supports. It's translation / terminology.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[brvs2014]

BigInch

The question is asked because the client requires me to maintain a standard because I do not need an anchor block, the pipe is designed with adequate flexibility, and having no rotating equipment connected to it then concludes that the displacement Of the pipe due to thermal expansion was not crucial to absorb the same with an anchor block the displacement is 10 mm, however the client does not accept the justification, due to this see if there are any paragraphs in the current legislation Which speaks of minimum limits or criteria for not using anchor blocks, the client does not have more knowledge of the subject however somebody I speak of blocks of anchor and he is blocked with the subject, the design in Caesar II realizes it because it is a Condition in the scope of the Project, however the calculations were made manually based on Criteria according to Peng.

Note: Sorry for my writing I'm not very good writing in English

 

[brvs2014]

DSB123

"Aerila" Meaning of pipe supports

 

[BigInch]

There is no standard, or legislation for when, or for when not to use an anchor block. It is a engineering design issue alone. There is no limitation on deflection or displacement of pipe. Any amount is fine as long as the pipe has not laterally buckled and remains within otherwise safe displacement limits. The reason is because absolute expansion depends on the length of the pipe. A 1000m long pipeline will have 1000 times the expansion of a 1m long pipeline, yet both pipes have the same temperature and the same stress (of zero when the pipes are not restrained). If you have no attached critical equipment, you really have no further issues. If it doesn't look bad, it's good.

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[LittleInch]

To be a bit picky here, a 1000m buried line will not expand 1000 time 1m, but a lot less as the pipeline will become locked up and fully restrained between 100 to 200m of burial.

Otherwise agree, each design is different but flexibility is the key.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BigInch]

As I said, when the pipes are not restrained

Technology is stealing American jobs. Stop H1-Bs for robots.

 

[brvs2014]

Thank you for your answers!!

 

[KevinNZ]

You do need anchor blocks when the pipe is made from slip joints. Think drainage lines and old hydro penstocks. Without anchor blocks the joints just pull apart under pressure.

 

[BigInch]

KevinNZ, That's a great reason. It seems that we all assumed it was welded pipe or that no anchor blocks were otherwise intrinsically needed. Can we move your answer up to the first response.

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[LittleInch]

The OP has stated it's a X42 crude oil service. That's a welded pipeline, not a push fit water line.

Do agree that some lines need it due to their type of construction, but I think it's pretty clear to me it's a welded line we're talking about here...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BigInch]

Right. That's good. He even says aerial. I guess that part won't have anchors.

Technology is stealing American jobs. Stop visas for robots.