elevated support for multiple pipes 1

[Structures33]

Hey there - I need to provide a detail for supporting 4 steel pipes laying side by side. The support will be 7' high and outside. I am not familiar with pipe support products beyond stanchion saddle-type supports. The client has provided a sketch of what they envision - a single steel pipe column supporing a platform at the top. What is typically used for the platform supporting the pipes?
Thanks

 

[DSB123]

Structures33,
What you are describing is what is normally referred to as a T post pipe support. The crossmember at the top of the vertical column can be any suitable structural section. However these forms of support may be subject to overturning moments and I have seen these collapsing due to a combination of loading and corrosion. I would try and get your Client to change the vertical post from being a hollow section to being an "open" section where you can monitor any corrosion. With hollow sections you cannot easily see the corrosion until it is too late and the support and pipes collapse. Ideallt a goal post support would be a far better option.

 

[BigInch]

I don't see anything wrong with using O or WF for columns. I've installed hundreds of both. O have their advantages as they provide a constant section modulus in all directions, so are well suited to act as columns when pipe axial frictional loads are high and approximately equal to lateral loads on the column from wind and seismic forces, etc. If lateral loads are high and longitudinal loads are small, maybe you should use a WF, but IMO, either can be used. "O"s are also used extensively and almost exclusively offshore as they present the minimum surface area exposed to corrosion and are easy to paint since they don't have all the nooks, crannies and corners as you find on WFs. In fact, almost all main structural members offshore are tubulars, so I don't buy into the corrosion issue too much, given they are well painted and maintained. IMO, nothing wrong with a pipe column and a WF on the top, except the connection of the two might get more complicated if bolted, so it would probably be more convenient to use a shop welded full encirclement fillet or Full pen welds.

Where I do get concerned about corrosion is between the pipe placed on top and the beam holding them up. That's the biggest corrosion problem point that I've always noticed, but you'd have that problem in all cases.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[IFRs]

If the pipes are 2", no problem.
If they are 36", BIG problem!
Other things to look at:
Wind loading when empty
Seismic loading when full
Thermal expansion
Water hammer
Shoe design
Soil conditions
Cross bracing between supports
What is under the pipes
Etc

 

[BigInch]

Only a 36" problem.

But if the pipes are 36", chances are you can get your hands on 36" pipe columns. Sometimes a good reason in itself to use "pipe pipe supports".

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[Structures33]

The pipes are 4" maximum and are natural gas lines. The loads will not be a problem.
What I'm planning to use is a 6" pipe column with a C10x25 for the "T" at the top (legs of the channel pointing down). The column will be welded to the channel.
What do you recommend using to secure the pipes to the channel?

 

[MJCronin]

All,

I have also been involved with many "T-pole" type pipe supports in process/utility construction.

Every utility/chemical plant seems to have thier own standard design (some are much better than others...)

It is important to note that the piping actually does form part of the structure. The piping run can be counted as providing some axial stiffness in the composite structure. (I know that there are those that will argue with me on this matter)

I suggest that you consider smaller WF steel sizes: w8x31 or W6 for the vertical post and W4x13 for the horizontal member. Use weather resistant coated U-bolts to secure the piping. The column bas can be either set into a poured concrete "sonotube" or welded to a square plate and anchored to an existing structure.

If the piping run is long, you may want to provide lateral support to the rack by using a two-post version of the support (with cross bracing) on every third support.

My opinions only..

-MJC

 

[BigInch]

For natural gas lines you might want to look at CFR Title 49 part 192 for specific requirements for supporting gas pipes to avert the corrosion issue I mentioned above. Typically adjustable chair supports are used to allow easy visual access for inspection. Additionally full encirclement pads are required for weld-on shoes/supports, vulcanized rubber pads under u-bolts, between shoes and pipe etc.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[DSB123]

Biginch,
Tend to disagree with your observations regarding internal corrosion of hollow sections. Yes I agrre with you that the main structural sections are tubulars but from what I remember is that in older units these legs are well holed due to corrosion and have had extensive repairs needed. My experience is not with "putting these supports in " as you mention but dealing with the aftermath when they have collapsed due to a combination on unseen internal corrosion and poor maintenance of the paintwork. I have had 28"nb steam mains with tubular anchor attachments that have suffered in this way also. So the site has "banned" the use of hollow sections because you cannot see the corrosion nor can you paint the internal surface of the tubulars.

 

[BigInch]

I've lead the underwater NDT team on platform inspections before we bought 5 of them of varying ages to dismantle the production equipment and install pipeline junction platforms. I've been on one platform in the GOM that was installed in 1949. Condition? Rusty deck grating. Poor. Pipe handrails good. Main members, excellent. Boat landings: corrosion where impacted. Primary pipe and equipment supports: very good.

Lord knows I'm not saying all places in the world are similar, just that for most places, IM experience pipe -pipe supports have never presented any more of an issue than WFs where I would have to say that Os would be disadvantage and there arn't too many worse conditions as the splash zone on offshore platforms. In fact, quite the opposite.

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[BigInch]

Found the CFR part I was thinking about;

http://ecfr.gpoaccess.gov/cgi/t/tex...v8&view=text&node=49:3.1.1.1.3.4.9.13&idno=49

192.161 Supports and anchors.
(a) Each pipeline and its associated equipment must have enough anchors or supports to:

(1) Prevent undue strain on connected equipment;

(2) Resist longitudinal forces caused by a bend or offset in the pipe; and

(3) Prevent or damp out excessive vibration.

(b) Each exposed pipeline must have enough supports or anchors to protect the exposed pipe joints from the maximum end force caused by internal pressure and any additional forces caused by temperature expansion or contraction or by the weight of the pipe and its contents.

(c) Each support or anchor on an exposed pipeline must be made of durable, noncombustible material and must be designed and installed as follows:

(1) Free expansion and contraction of the pipeline between supports or anchors may not be restricted.

(2) Provision must be made for the service conditions involved.

(3) Movement of the pipeline may not cause disengagement of the support equipment.

(d) Each support on an exposed pipeline operated at a stress level of 50 percent or more of SMYS must comply with the following:

(1) A structural support may not be welded directly to the pipe.

(2) The support must be provided by a member that completely encircles the pipe.

(3) If an encircling member is welded to a pipe, the weld must be continuous and cover the entire circumference.

(e) Each underground pipeline that is connected to a relatively unyielding line or other fixed object must have enough flexibility to provide for possible movement, or it must have an anchor that will limit the movement of the pipeline.

(f) Except for offshore pipelines, each underground pipeline that is being connected to new branches must have a firm foundation for both the header and the branch to prevent detrimental lateral and vertical movement.

[35 FR 13257, Aug. 19, 1970, as amended by Amdt. 192–58, 53 FR 1635, Jan. 21, 1988]

http://virtualpipeline.spaces.msn.com

"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain

 

[himat42]

Structure33

Please looked at a paper On
"Check pipe support orientation" by: C.V.Char
Hydrocarbon Processing, Sept. 1975, pp. 207-212.
You need Mr. char paper to desig your case. He has given detail structural calculations of pipe support with different cases.