Hot Tap

[OilGasMan]

Has anyone ever done/seen a hot top done on a weld cap before? Not a typical procedure, but I am looking for examples from someone who has done on through the weld cap.

 

[unclesyd]

We made 2 hot taps on a 300 psi steam line through a 12" weld cap. The line was CS Sch 80 and it was treated the same as it was in the run of the pipe.

One was a 3" and one was a 4".

Can you comeback with some more details as to sizes , temperature, and pressure?

 

[OilGasMan]

The line we are tapping into is 40# Steam, 12" Std Pipe. We are looking at using a weld-o-let with a 10"x12" tap.

 

[unclesyd]

The 40# steam is no problem. The only problem I see as you are approaching 1:1 with the 10x12 Weld-O-Let. Depending on the exact shape of the cap you may run into welding problems. You may have trouble getting the required weld profile for the Weld-O-Let.

I would run this by the people that are going to do the actual hot tap.
They can also help with the details on testing the nozzle prior the the actual tapping.

 

[DaEarl]

I can confirm UncleSyd's concern from my own observations of the same thing done on a 150# steam 12" Weld Cap at my refinery.

The Hot Tap guys were concerned about a proper weld profile with a 8" on 12" tap.

Like Syd said, talk it over with the experts who specialize in hot taps, plugging, etc.

 

[jte]

If I understand this question correctly, you are trying to basically extend a 12" pipe with a cap in the longitudinal direction. In this case a 10x12" Weldolet would be an incorrect application - the profile will be all wrong on the fitup to the cap. If you're determined to use an 'olet use a "flat-olet" or basically one which is 10x(inifinity) which will be essentially flat on the run pipe side and thus will mate up to the cap smoothly.

But... Would you consider using a 12" x 10" reducer, pushed up against the cap and welded out to provide a continuous outside profile / wall thickiness from the 12" line to the reducer. Or, a 12" long weld neck flange - same thing, butt it up against the cap and weld it out. You'll basically wind up with a solid 12" pipe by the time you're done cutting the coupon out of the cap.

jt

 

[jistre]

Just to play all of the options, can't you wait till scheduled downtime to cut the cap off and add a reducer/pipe run the traditional way?

I assume that since you asked about hot tapping you either don't have any downtime on the line to make use of, management doesn't want you to wait for that downtime, or some other good reason not to wait and do a standard pipe run.

 

[HotTapper]

Hot Tapping into end caps is a somewhat specialized area, but they are performed if it is the best option available. Occasionally the material can become hardended due through the forging or extrusion process, so additional care needs to be taken when choosing a cutting method.

Approaching size on size presents different considerations, ie, curvature and depth of cutting heads needs to be considered.

An experienced hot tap service company can assist in the design and guide you through the process. It should help eliminate any pitfalls.

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