My client would like to seal the gap between shell flange like this, is it ok? 1

[pv_mkk]

The reason is

1. The gasket at shell flange is broken and there is some vapor leakage when the media inside was heated.
2. It takes a long time to disconnect all piping and agitator on top of the vessel in order to replace a new gasket.

So my client would like to seal the gap between shell flange by welding plate inside of vessel around the shell flange gap as shown in the picture for temporary.

They will consider changing a new vessel in the future.

The vessel design condition is 25kPa@150C

Is the solution practical? or any advise would be appreciated.

 

[LittleInch]

Well that's a pretty low pressure and looks like they just want to weld on a plate over the hole?

I can't work out what that fitting is for the life of me.

There are also flange sealing kits you can get / use - things like this

https://www.teaminc.com/service-solutions/maintenance-repair/leak-sealing-repair

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

 

[r6155]

Gasket width is very small. Contact your gasket vendor to select new material and avoid welding.

Regards

 

[pv_mkk]

Unfortunately, the flange is quite big (OD~1800mm) and under operation platform. this solution might not practical in time-wise.

This is the same design of existing vessel which never leakage before.

Anyway, Thank you guys both.

 

[Dhurjati Sen]

Dear pv_mkk,

What is the service of the vessel?

These temporary boxes are okay for water / steam but not for hydro carbons.

Regards.

DHURJATI SEN
Kolkata, India

 

[r6155]

You should investigate the cause of leaks. Do you have any information?
Something is wrong with torque and sequence of bolts assembly.

Regards

 

[LittleInch]

Where did 1800mm come from?? Your drawing indicates about 60 or 70mm.

Which gasket is failing?

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

 

[r6155]

LittleInch: Please see the drawing again. The plate 65 x 10 mm is a cylinder aprox diam 1800 mm

Regards

 

[LittleInch]

Ah , Ok, but maybe you can see more of the drawing than I can.

All I see is

Even so, it's only an 1800 diam ring. you could split this into sections and weld up. what's the problem?

If they are going to weld the flange shut then why not just weld the gap? Still use the bolts but seal weld the gap. Especially at 0.25 bar

Or just fill the gap with some goo that goes solid like a 2 pack epoxy of some sort.



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

 

[r6155]

pv_mkk say “This is the same design of existing vessel which never leakage before”

Why leaks now??!!!. pv_mkk must investigate the cause of leaks

I suggest maintain actual design and avoid welds.

Regards

 

[r6155]

One more. Avoid welding in confined space.

Regards

 

[SnTMan]

Wouldn't be my first choice, but for a temporary repair in non-hazardous service it'd be acceptable, if all the other options were worse. And if all the involved parties agree.

BTW, that is kind of an odd flange(s) detail. The facings(s)/gasket surface(s) appear to be separate from and welded to the ring(s). New one on me.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[marty007]

BTW, that is kind of an odd flange(s) detail. The facings(s)/gasket surface(s) appear to be separate from and welded to the ring(s). New one on me.

This is quite common in high alloy clad construction. You can make the flange carbon steel, and the facing can be something exotic (hatelloy, inconel, etc...). It can save a lot of money in raw material. The steps in the facing are unusual though...

 

[chicopee]

If it is a seal weld it may not be a problem as long as it is not full penetration welding. Seal welds are normally used on leaking tube ends projecting out of tube sheets in steam and hot water boilers. Since we are not looking at steam and hot water as the media, I would double check on the construction code of the vessel and research if seal welds are acceptable.

 

[SnTMan]

marty007, yeah, I suppose that could be. Cylinders would presumably be hi-alloy as well. No clue as to metallurgy in any of the foregoing.

Steps in the facing seem to be consistent w/ confined joints.

I am more used to seeing forged CS weld neck flanges w/ weld overlay at ID and facings, cylinders either clad or WOL.

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[BJI]

It looks like your bolting is only 3/4", so likely under-bolted. The flanges look weak, essentially no hub with thin shell wall, so 40mm flange thickness is probably insufficient. The gasket is also too wide, looks to be at least an inch wide. So you would have insufficient gasket stress, compounded by inability to increase your bolt load sufficiently, due to the undersized bolts and risk of permanent flange deformation. If the flange strength is sufficiently low you might already have high flange rotation.

The most likely difference between this vessel and the sister vessel comes down to poorer joint assembly. Flatness may also be an issue depending on your gasket type. I would agree with r6155, work out why it is leaking and fix the problem.

 

[CuMo]

Wouldn't be my first choice, but for a temporary repair in non-hazardous service it'd be acceptable, if all the other options were worse. And if all the involved parties agree.

BTW, that is kind of an odd flange(s) detail. The facings(s)/gasket surface(s) appear to be separate from and welded to the ring(s). New one on me.

Regards,

Mike

I bet it is a stainless steel facing welded to a carbon steel flange.

 

[hacksaw]

Unsafe design regardless of the surface at a minimum it will not be a reliable "fix."

 

[DriveMeNuts]

With the very low pressure, buy a half dozen tubes of high temperature RTV sealant and smear it over the inside of the gasket joint. Sticks to and seals absolutely everything.

A bodgy temporary fix.