-
First of all you should aware of the system which you are going to
be tie-in.if it is process line veriety of precaution to be take
care.if it is a fuel gas line,flare line each should be as seperate
safety measure.
- Reduce the line pressure below working pressure.
- Isolate the system according the line precaution.
3.provide hose from the drain point away from the tie in point.
4.The hose to be put in the water tank.
5.If possible provide wright size gas plug.
6.Normaly the tie-in flange is welded,even it is u/g or a/g
7.Welding operator should be very competant.
8.The SUPERVISOR SHOUD BE STRICTLY FOLLOW THE OUT GOING.
- In PipingDesign@yahoogroups.com, MAIL MUG <melvin_magbanua@...>
wrote:
>
> The pipelines 10" and 16" (bare, no coating protection) are all
above ground installation.
>
> thank you for the info regarding the PIPE FREEZING
method/technique. I will communicate with that company to get their
qoutation/proposal (details) and to include the cost involved.
>
> Melvin
>
> ----- Original Message ----
> From: elie altawil <eliealtawil@...>
> To: <a href="/group/PipingDesign/post?postID=eXapa-uB_8lfCjotxSUzh7925Os71WOZq13tCZ5u02IEfy2VkvyL7Gre6CLHfg2xONPBe0x5F9Xpr-tBh6Z-fw0EjQo">PipingDesign@yahoogroups.com</a>
> Sent: Thursday, January 25, 2007 3:57:13 AM
> Subject: Re: [PipingDesign] TIE-IN JOINTS - FLANGED OR WELDED?
>
> You did not say if the tie-ins are above or below ground. Burried
flanges is not prefered, but it could be done by using ceramic
coated stud bolts and nuts and FBE coated flanges and welds.
>
> Leaks from below ground flange gaskets are hard to monitor and
detect early and very likely it will happen on of the 11 tie-ins.
>
> I have been involved with many tie in 12" to 30", we typically
maintain constant air flow from the upstream and downstream vents
toward the tie-in point with continuos LEL monitoring.
>
> For best in class operations, you can use the Pipe freeze plugging
method see http://www.pipefree zing.com/ for more information.
>
> Pipe Freezing
>
> Pipe freeze plugging is a simple, cost-effective method to perform
pipe maintenance or line modification without shutting down your
plant process. Using liquid nitrogen, Freeze Service, Inc., a
division of T.D. Williamson, Inc., can isolate the problem area in
the line with SOLID freeze plugs of the fluid within the line. This
allows the job to be done with very little draindown or refill, no
loss of expensive process fluids, and in many cases, no system
downtime. Once the work is completed, the plugs are thawed and the
line is back in operation. Standard freeze plugs range in size from
1/2" to 48" OD.
>
> Successful pipe freezing is accomplished by establishing solid
freeze plugs and maintaining them during the duration of the
project. Freeze Service's freeze plugs are constantly monitored and
designed to withstand up to 8,000 psig line pressure or 225,000
pounds force. Independent laboratory tests have documented that no
physical change in the structural matrix of the pipe occurs due to
the controlled freezing process.
>
>
> melvin_magbanua <melvin_magbanua@ yahoo.com> wrote:
> I would like to solicit your opinion and advice gentlemen
regarding
> our tie-in joints (11 joints) in our upcoming pipeline
> repair/replacement (ASTM
> A106 PIPE Std thickness) activities for our crude oil transmission
> line 16" and 10", both are 50 km long, 50 yr old lines.
>
> Can we use a flange joint for the tie-ins instead of welded
joints?
> I proposed flange joints since we can not insert pipeline balloons
or
> Pipe plugs during tie-in if we don't have a flange connection.
>
> My question is. if flange connection acceptable for line like this?
>
> The line will be drained before it will be handed over to the
> contractor but for sure, flammable gases would still be emitted by
> the remaining sludge inside the line.
>
> One incident similar to this tie-in in Kuwait National Petroleum
> Company –KNPC which they are going to do a tie-in welding in a 30"
> line about 1.5km long between isolating valves, at the beginning
teh
> LEL readings was zero, but after sometime when during tie-in
welding
> was goin on, the flammable fumes emitted by the remaining sludge
> inside the pipe was ignited and the welder was thrown 6 meters
away
> due to the explosion and was hospitalized due to 3rd degree burns.
>
> It was a good lesson learned and don't want it to happen in our
tie-
> in project. Please I need your input gentlemen so I can consider
it
> in our scope of work (constructability issue and safety will be
> considered).
>
> ------------ --------- --------- ---
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Received on Sun Jan 28 02:18:00 2007