Tube plugging 5

[niteshgargeck]

Hello

My question is there any standard or reference which gives exact guideline that whether we have to puncher a tube before plugging. This is the case of boiler where we have leak in a bend.
now can i remove the bend and plug the tube or i have to puncher the tube then plug it.

 

[chicopee]

What type of a boiler is it and where is the tube located within the boiler?

 

[niteshgargeck]

Its a FD type gas fired boiler.
tube is in economizer panel.

 

[Christine74]

You should ALWAYS puncture/vent tubes prior to plugging them in order to protect workers from being injured by tube plugs that can spontaneously eject:

http://www.tandfonline.com/doi/abs/10.1080/01457630252800377?journalCode=uhte20

-Christine

 

[niteshgargeck]

thanks cristine but i m looking for some code or firm reference on same subject.

 

[r6155]

Try with "plugging of tubes" in TEMA

Regards
r6155

 

[EdStainless]

You don't need a std to tell you to do what is proper practice.

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P.E. Metallurgy, Plymouth Tube

 

[niteshgargeck]

@r6155 in tema they did not mention anything about puncturing the tube.

 

[r6155]

Sorry, I agree with EdStainless

Regards
r6155

 

[Aconnell]

See ASME PCC-2-2015 Article 3.12 Para 4.2 (a) on Page 133.

 

[niteshgargeck]

hey Aconnell i do not have copy of tht standard. can you upload it for me,

 

[jte]

niteshgargeck-

You can get PCC-2 from ASME.

https://www.asme.org/products/codes-standards/pcc2-2015-repair-pressure-equipment-piping-(1)

It is also available on IHS provided that your subscription covers it or you purchase thru them.

I do not condone theft of intellectual property, and as copyrighted material it would be illegal and unethical for anybody to share a copy with you or anybody else. If the $139 price is too much, then I suppose the heat exchanger you are working with is not particularly valuable to the plant either...

 

[Aconnell]

Hello niteshgargeck

I thought about posting an excerpt of the paragraph, however for the reasons jte mentioned I decided against it. As jte mentioned it doesn't cost that much and if your company owns and maintains pressure equipment it is a good reference to have on hand anyways.

 

[niteshgargeck]

thnx Aconnell

 

[jte]

Good move, Aconnell. For clarity, I do not oppose quoting a paragraph or two, properly cited, where it makes sense in a post. When it is a clear attempt to avoid payment for a product, it crosses the line for me. In the case of PCC-2, a paragraph or two would be ok in my mind, an entire Article, and certainly the entire standard, would not.

 

[EdStainless]

I appreciate the honest and open discussion of the issues around copyright.
Ethics matter. Thanks guys

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P.E. Metallurgy, Plymouth Tube

 

[niteshgargeck]

I hope guy who invented wheel shud also have patented it. I was not asking for whole document just wasted to hav knowledge of particular topic.
But i appreciate efforts put by respected members

 

[chicopee]

I'll tell one of the practices that I read when a tube leak on older model fire tube boilers and no tube replacement can be done at the time. Wood plugs with a slight taper would be driven thru both tube sheet ( rear and front) holes, then, refractory cement would be covering the ends of the wood plugs exposed to the fire side. Apparently this has been done with success since on the water side the wood would further expand and prevent the wood plugs from being ejected from the steam pressure. On the fireside the refractory would protect the wood from being consumed by the hot gases. In your case, such practice may work depending on the pressure of the feed water flowing thru the economizer.

 

[crshears]

An old book I have describes how to temporarily plug a fire-tube boiler tube leak partway along the tube; a wooden dowel is lathed down to a clearance fit, then halfway along the dowel a waist is machined into it so it somewhat resembles a sewing bobbin.

The dowel is then pushed down the leaking tube until one of the clearance halves has passed the leak, at which point the efflux of water will cause the wood to expand tightly against the ID of the tube, sealing the leak and allowing the boiler to be returned to service.

Since there is no gas flow through the tube, there is little danger of the wooden plug ever charring unless it is very close to the "hot end" tube sheet, in which case it may be necessary to parge over the end of the tube with a bit of refractory cement.

Hope this helps someone.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[numberfive]

Plugging of tubes in fire tube boilers should never be done unless the plugs are secured with a "calculated" strength weld.

Tapered tube plugs simply driven into the ends of the tubes can fail and be ejected with deadly force.

I have seen a couple of procedures from boiler manufacturers that use a stay rod through the length of the tube to hold the plugs in place so they cannot be ejected.

A tapered plug should only be used when it is in an application where the pressure of the boiler will be acting to drive the plug securely into the tube (i.e.: plugging of generating tubes in the drums of a water tube boiler).

We've also removed tubes from service by capping with the use of a butt weld or socket weld cap sized to fit the tube. This would be like for removing a superheater or economizer element from service. Cut the tube stubs near the header and install the caps to remove the leaking or wasted tubes from service.

Caution should always be used when using this method as well. A capped tube stub that is exposed to radiant or convection heat can overheat and fail because the steam or water flow has been cut off.

If you're going to cap a tube stub make sure it's out of the gas path. If this is not possible, hire an engineer to design a plug that can be installed directly into the header.

As always, make sure your AI is on board with the repair plan.

numberfive