Re: Anchor Block Requirement

Thrust Blocks on Underground Piping:

There are two types of pressurized underground piping systems, those that support axial tension and those that do not. Bell and spigot type end connections do not support axial stress in the pipe and so the end thrust (P times A) must be carried by the soil via an anchor block or the pipe joint will separate.

When a buried pipe is circumferentially welded at each joint such restraint is not needed unless the axial thermal or pressure expansions produce excessive stresses or displacements, usually however, the solution is to permit the expansion, not try to restrain it.

Anchor blocks on circumferentially welded pipe can be placed to:

1. Reduce the stress if the displacement cannot be absorbed or tolerated. In Holland peat is used in the area around buried bends to soften the backfill and permit displacement. Dow also makes a polystyrene product in several grades that can be used to perform the same function. Permitting the displacement is usually the solution in these case.
2. Stop displacements in areas where transitions to above ground pipe, or where tie-ins or other connections exist that cannot tolerate the movement.
3. Where large waterhammer loads are expected to prevent excessive pipe movement.

There are other special conditions, but I don't get the feeling that these cases are being discussed.

• Original Message ----- From: "saeed ahmed" <n2701h@yahoo.com> To: <PipingDesign@yahoogroups.com> Sent: Wednesday, October 02, 2002 11:01 AM Subject: RE: [PipingDesign] Anchor Block Requirement

>
> Actually there is a caculation which gives us the requirement of thrust
block for underground piping at bend. Such bends can be 90 deg or less than 90 degree in underground piping.
> Saeed.
> Geoff Stone DD&D Australia wrote:Saeed,
>
> Why do think you need a thrust block?
>
> Geoff Stone
> --- saeed ahmed wrote:
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> Thanks Geoff Stone for the reply.
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> Iam talking about thrust block requirement in underground piping at bend.
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> Saeed.
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>
> Steve McKenzie wrote:Hi Geoff
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>
>
> I use them on steel lines where water hammer is an issue.
>
>
>
> Cheers
>
>
>
> Steve McKenzie
>
>
>
> -----Original Message-----
>
> From: Geoff Stone DD&D Australia [mailto:blenrayaust@yahoo.co.uk]
>
> Sent: Monday, September 30, 2002 9:37 AM
>
> To: PipingDesign@yahoogroups.com
>
> Subject: Re: [PipingDesign] Anchor Block Requirement
>
>
>
>
>
> Saeed,
>
>
>
> Please provide more details as it is difficult to understand why you are
>
> considering an anchor block for underground piping that is welded?
>
> Anchor blocks are sued for rubeer ring jointed ssytems such as ductile
iron
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> and
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> thermoplastics but not a welded steel pipe.
>
>
>
> Geoff Stone
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> --- n2701h wrote:
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> ---------------------------------
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> In calculating the anchor block requirement at underground
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> piping
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> bend,there are two variable involved ,one is tie-in temperature and
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> the other is allowable piping deflection.What should be the critaria
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> taken in the calculation?
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> With thanks
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>
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> Saeed
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>
>
> n2701h@yahoo.com
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> Texas Flange - a good source for information on industrial flanges, all
> they
>
> ask is for referrals for designs they help with.
>
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>
> 877-610-8924.
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>
>
> www.texasflange.com
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> Design Detail and Development (a division of Blenray Pty Ltd)
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> We specialise in pipe network and waterhammer analysis, pipe stress
>
> analysis, the design of buried pipelines and thermoplastic pipe systems.
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> Design Detail and Development (a division of Blenray Pty Ltd)
> We specialise in pipe network and waterhammer analysis, pipe stress
analysis, the design of buried pipelines and thermoplastic pipe systems.
> Local tel 0402 35 2313 fax 02 8850 2313
> Overseas tel 61 402 35 2313 fax 61 2 8850 2313
> Mail Address PO Box 1351 Castle Hill NSW 1765 Australia
>
> __________________________________________________
> Do you Yahoo!?
> New DSL Internet Access from SBC & Yahoo!
> http://sbc.yahoo.com
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> Texas Flange - a good source for information on industrial flanges, all
they ask is for referrals for designs they help with.
> 877-610-8924.
> www.texasflange.com
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Received on Wed Oct 02 19:21:00 2002