BS1042 describes three tapping methods for orifice plate pressure tappings;
D and D/2 tappings, flange tappings, corner tappings. The pipe diameter
range is up to 1000mm.
For flange tappings, the tap points must be nominally one inch from each
face of the orifice plate.
I would expect the reason why tapping flanges in larger sizes are not available is because there is very little demand for then.
Orifice plates "waste" a fair amount of energy; typically 20% of the measured pressure differential (times flow), and much more if low flow accuracy is required.
In larger sizes, many use venturi tubes, magflows, annubar, ultrasonic and heaps of other flow measurement devices. The energy savings normally justify the use of a more expensive flow measurement device.
Cheers
Steve McKenzie
-----Original Message-----
From: alwyn KAYE [mailto:altecheng@primus.ca]
Sent: Sunday, May 11, 2003 7:05 AM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Orifice Flange
i dont understand this answer. Are you saying the orifice is in the pipe in bigger sizes. This is not right. Orifice flanges have the orifice sandwiched between them, I dont beleive it has anything to do with instrumentation or tappings in the pipe (you said ......."because the tappings are not from flanges but from the connected pipes").
The orifice still has to be mounted into some rigid conmector whatever size the flange or pipe is.
Hello!
Orifice flanges (flanges with tappings for instrumentation connection) are usually bought only for sizes up to 12" (16" is mostly the upper limit). Beyond this size, the flanges are normal ones (B-16.5 or B-16.47A/B) because
the tappings are not from flanges but from the connected pipes (i.e. the hub
part need not be thicker to compensate for the tapping hole/holes...and hence ordinary flanges).
We may ask why are tappings from pipes and not the flanges. For this, we would need to go back to basics, to hydraulics, to bernouli's theorem, to "vena contracta" and the distance at which it is formed after the orifice, the accompanying change in velocity and drop in pressure. In fact, orifice has its demerits too, due to which other measuring alternates are used by Instrumentation at times.
Mahavir
-----Original Message-----
From: Sree Vardhana P.G. - [mailto:s_vardhana@yahoo.co.uk]
Sent: 10 May, 2003 1:37 AM
To: PipingDesign@yahoogroups.com
Subject: Re: [PipingDesign] Orifice Flange
well ansi B16.5 shows upto 24" only for the flanges
As per my knowledge if you wanted to have flanges
above 24" then u need to see ASME B16.47 class A which
includes MSS SP44 standards.
if you wanted in API 605, then now it is covered in
ASME B16.47 class B for above 24" flanges.
with regards
sree vardhana p.g.
--- virgilio balbuena <virgiliobalbuena@yahoo.com>
wrote: > Friend,
> Well ansi B16.36 show up to 24" only ..but if
> you
> will notice the flanges mention about 24" will be
> the
> same to MSS Sp 44 standard and by the way ,Do you
> know
> what is orifice flanges ? okay the flanges is
> standard
> and holes on the flanges upsteam and dowstream will
> measure the differencial pressure and will be
> converted to Flow.So the important part of this
> assembly is the orifice between the flange.
>
> Regards,
>
> gil
> --- lmathew@technip-coflexip.com wrote:
> > Dear friends,
> >
> > I am a new Member.
> >
> > Can any body tell me is any standard for orifice
> > flange assembly for sizes
> > 26" and above.
> > ( ASME B16.36 covers sizes up to 24")
> >
> >
> > Regards
> > Liju Mathew
> >
> >
> > ----------
> >
> > This e-mail and any files transmitted with it (ë
> > Message û) are confidential and may contain
> > privileged information.
> > This Message is intended solely for the
> > addressee(s). If you have received this Message in
> > error, please inform us promptly by reply e-mail
> > then delete the Message and destroy any printed
> copy
> > of it.
> > Any unauthorized use, review, retransmission,
> > dissemination, distribution, printing or copying
> of
> > this Message or any part thereof is strictly
> > prohibited.
> > E-mails are susceptible to alteration. Neither
> > Technip-Coflexip nor any of its subsidiaries and
> > affiliates shall be liable for the Message if
> > altered, changed or falsified
> >
> > [Non-text portions of this message have been
> > removed]
> >
> >
> >
>
>
> __________________________________
> Do you Yahoo!?
> The New Yahoo! Search - Faster. Easier. Bingo.
> http://search.yahoo.com
>
> ------------------------ Yahoo! Groups Sponsor
>
>
=====================================================
> Discussion List sponsor: The fluid flow calculations
> website - www.LMNOeng.com - LMNO Engineering,
> Research, and Software, Ltd.
>
=====================================================
> unsubscribe:
> PipingDesign-unsubscribe@yahoogroups.com
>
=====================================================
>
>
> Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
>
>
__________________________________________________
Yahoo! Plus
For a better Internet experience
http://www.yahoo.co.uk/btoffer
Yahoo! Groups Sponsor
=====================================================
Discussion List sponsor: The fluid flow calculations website -
www.LMNOeng.com - LMNO Engineering,
Research, and Software, Ltd.
=====================================================
unsubscribe: PipingDesign-unsubscribe@yahoogroups.com
=====================================================
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
----------
-------------Disclaimer-------------
The contents of this E-mail (including the contents of the enclosure/(s)
or attachment/(s) if any) are privileged and confidential material of
ENGINEERS INDIA LIMITED (EIL) and should not be disclosed to, used by or
copied in any manner by anyone other than the intended addressee/(s). If
this E-mail (including the enclosure/(s) or attachment/(s)if any ) has
been received in error, please advise the sender immediately and delete
it from your system.
-------------Disclaimer-------------
[Non-text portions of this message have been removed]
Yahoo! Groups Sponsor
Research, and Software, Ltd.
Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
[Non-text portions of this message have been removed]
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Sat May 10 19:08:00 2003
This archive was generated by hypermail 2.1.8 : Mon Oct 27 2008 - 20:24:00 EDT