Geoff -
Thanks for your additional thought. See my reply to Randy Conner...the conservatism is not due to fire pumps in this case.
Ken A. Nisly-Nagele, P.E.
Project Engineer, Mechanical
Applied Engineering Services, Inc.
7999 Knue Road
Indianapolis, IN 46250
317-585-8920
-----Original Message-----
From: Geoff Stone DD&D Australia [mailto:blenrayaust@yahoo.co.uk]
Sent: Monday, October 17, 2005 4:46 PM
To: <a href="/group/PipingDesign/post?postID=ZEwhsYbpWdxQ3AACBl20FWr75k5JAjX1X0nkneMaVtAlpS5IokklTPc0GklM-WqbHdg1M4_t1tqbjFHijqs0ZbkIGmU">PipingDesign@yahoogroups.com</a>
Subject: RE: [PipingDesign] Double Restraint of DI Piping
Ken,
If this is a firewater line the owner may be concerned with waterhammer and wants the conservatism in the design.
Geoff
Ken Nisly-Nagele <knislynagele@applied-e-s.com> wrote: Geoff -
I understand that ground conditions are not unusual or poor. So, thrust blocks would not be relatively large for this site.
Being a buried piping system, the mechanical joints offer the advantage of accepting some relative piping deflections and permitting gradual offsets in alignment and changes in elevation. These are the reasons that a mechanical joint system is being used rather than a flanged joining system.
What I am finding is that the Factory Mutual (FM) working pressure rating for the restrained joints is 175 psi, which is considerably less than the working pressure rating of the piping and fittings, which is 350 psi. (The UL rating for the restrained joints is 350 psi.) It may be that the insurers may have requested the additional thrust blocking or rods due to the lower FM rating.
As suggested, it may be that the requirements for double restraint have not been carefully reviewed.
Thanks for the comments, I'll post more if/when a reason for double restraints is identified.
Ken A. Nisly-Nagele, P.E.
Project Engineer, Mechanical
Applied Engineering Services, Inc.
7999 Knue Road
Indianapolis, IN 46250
317-585-8920
-----Original Message-----
From: Geoff Stone DD&D Australia [mailto:blenrayaust@yahoo.co.uk]
Sent: Sunday, October 16, 2005 4:26 PM
To: <a href="/group/PipingDesign/post?postID=ZEwhsYbpWdxQ3AACBl20FWr75k5JAjX1X0nkneMaVtAlpS5IokklTPc0GklM-WqbHdg1M4_t1tqbjFHijqs0ZbkIGmU">PipingDesign@yahoogroups.com</a>
Subject: Re: [PipingDesign] Double Restraint of DI Piping
Hi,
I have never come across sucha requirement. Suggest if the ground conditions are so poor then a change to a welded steel pipeline is in order.
AS2280 DI PIpe has Class 35 pipe. ie nominal 3500 kPa. Installation techniques are generallythe same as Class 20. 2450 kPa(350 psi) is not such high pressure. Given that the thrust blocks would become large why not use a flange class?
Geoff Stone
Ken Nisly-Nagele <knislynagele@applied-e-s.com> wrote:
For underground water mains (ductile iron at 350 psi working pressure),
generally 12 to 24 inch diameter, a client's specifications appears to
require restrained joints AND thrust blocks, anchors, or tie-rods. What
I
would describe as double restraint. My experience has been restrained
joints OR thrust blocks, anchors or tie-rods. We are scheduled to
discuss
this with the client, and I am interested to know whether others have
provided double restraint design and for what reasons? To be doubly
sure of
restraint when cost is not a primary concern?
Ken A. Nisly-Nagele, P.E.
Project Engineer, Mechanical
Applied Engineering Services, Inc.
7999 Knue Road
Indianapolis, IN 46250
317-585-8920
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Design Detail and Development (a division of Blenray Pty Ltd)
Mail Address PO Box 1351 Castle Hill NSW 1765 Australia Tel Mob 0402 35 2313 Office 02 8850 2313 AH 02 8850 2324 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)
Mail Address PO Box 1351 Castle Hill NSW 1765 Australia Tel Mob 0402 35 2313
Office 02 8850 2313 AH 02 8850 2324
We specialise in pipe network and waterhammer analysis, pipe stress
analysis, the design of buried pipelines and thermoplastic pipe systems.
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Yahoo! Groups Links Received on Sun Oct 23 18:06:00 2005
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