High Temp Line Stop Types 2

[Krausen]

I have to hot tap & line stop/stopple 3 different steam lines in near future (15#, 90#, & 400# steam lines). My only line stop experience is with low temp stopples from TDW using the standard pivoting stopple head with elastomer cups/seals. The last time my site attempted a line stop on a similar 400# steam line, it was a train wreck requiring multiple contractors to finally complete successfully.

Does the forum have any particular line stop type recommendations for steam lines with design temps up to 700F? In these cases, the lines will have no flow through them during the line stop operation. I understand there are metal-seated “across the line” type line stops (e.g. TEAM Hi Stop) marketed for these types of applications, but was curious of forum’s experience with any of these?

 

[LittleInch]

I would normally use the word stopple to describe what you seem to be talking about?

Line stop is usually something which stops a line moving physically.

400 psi steam isn't easy for sure and a lot will depend on the inner surface condition. Do you have information on that?

You might need two stoples to be honest and vent the gap. Or stick a bag in d/s the stople and vent the gap.

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[mk3223]

There is a potential risk of the hot tap/stopple operation on the high pressure & temperature steam line. Consider the alternative option or safety measures such as:
- have a new branch off from the existing line connection
- perform hot tap during the plant low operation demand period
- possibly reduce the steam header pressure for performing the hot tap
- prepare a contingency plan to block the line with stopple if the hot tap failed

 

[Krausen]

My understanding is the term “stopple” is the trademark name for a type of line stop by TDW. But either way, yes we’re talking the same general thing.

I don’t have any info on the ID conditions on the existing pipe, but I will be getting UT readings to measure current wall thickness at location of hot tap fitting install.

The “across the line” type stopple for high temp applications does not seal on the ID of pipe it appears either, instead cutting through the top & bottom of existing pipe & inserting a tapered plug vertically only to seat into the two cut-out holes. This results is a metal-seated type plug that can withstand the high temps as I understand

 

[LittleInch]

Actually, why are you doing this?

Hot tap doesn't need a stopple.

That's to cut out a section and replace.

Hot tap you do under operating conditions

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[Krausen]

All lines will be in operation, thus will require hot taps & stopples in order to replace existing block valves & modify existing piping in sections that are not isolatable. These are all steam supply or steam return (condensate) lines feeding or returning to/from units in a refinery. There will be no flow during the stopple operation since we are able to isolate one side of each supply/return line section with block valves, but not both sides. Thus the lines to be stoppled will still be under pressure but without flow. When we weld on the new hot tap fittings prior to stoppling, we will likely do this with flow in these lines still to help cool the hot tap fitting welds.

 

[LittleInch]

I think you're into very rare territory at 370C & 27 bar for a stopple type operation.

Have you tried Furmanite ipsco?

Oh and yes it seems "line stopping" is a term used generically, but is also used in piping...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[LittleInch]

Or

http://www.steamandprocess.com/linestopping.htm

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Krausen]

LittleInch - Thank you for suggestions. I am not familiar with either, but will investigate. Currently I’m working with TEAM on getting a quote for their “Hi Stop” type stopple purported to be rated for over 1000F using a metal-to-metal seat concept.

Yes, agreed, hot tapping & stoppling a line at these pressures & temperatures is not to be taken lightly. Wish me luck. I’ll report back in case any are interested

 

[LittleInch]

The posts stay open for 6 months and a conclusion is always welcome.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[saplanti]

Just be careful with hot tap application. Almost all the hot top equipment may not be allowing the piping to work at all operating conditions, they have limitations. You need to check with them/their catalogue/brochures.