Hydrotesting Boiler 1

[BenjaminM]

Good evening everyone.

As time has progressed our 100 HP boiler is having a harder and harder time keeping up. We have purchased a used 200 HP boiler and are planning on installing it this summer. Our 100 HP boiler will be shut down and primarily serve as backup.

We will need to hydrotest the boiler. We have the option of doing it ourselves or having the boiler service company do it for us. I have never done this before and I am looking for some advice.

I understand the general idea.
1)Open up the boiler.
2)Fill the boiler up with water getting out as much air as possible.
3)Button it up and slowly increase the pressure.
4) Hold at said pressure and check for leaks.

I believe the boiler's MAWP is 125 PSI. We plan to run the boiler at 100 PSI though.

I have heard in the past you should pressurize a vessel to 1.5x design pressure. Is this accurate? Should it be the MAWP instead?

After we have reached our intended pressure with no leaks, how long should we hold at that pressure? Is an hour sufficient?

What is the best way to pressurize the boiler? I have heard of using some type of hand pump. My boss intends for us to hook a pressure washer up to it, with a couple of cut off valves though. Is this reasonable?

From a legal point of view can I, an untrained guy with only a BS in Chem Eng and no PE certification, even do this? One of my personal goals in life is to be competent in all the things I do, and I do not want to neglect any regulations. I intend to document our procedure and results well.

Are there any major safety concerns with the test itself? Yes we will have substantial amount of pressure on this boiler, but it is all water. Should a seam crack or a tube sheet rupture is there any danger of projectiles flying at us, or would it merely be the equivalent of a leaky water hose?

Any advice or even a finger pointing in the right direction would be GREATLY appreciated.

Thankyou all for the help.

 

[ChiefengO]

Hi Myrdale

Boiler's are tested when they are new by certified personel to 1,5 x MAWP and not the design pressure. I guess you are pressure testing this boiler for your own interest and not to get it certified, as it's only approved companies or persons who can do that.
You can pressurte test what ever you want, but it will not be valid for any certification. So if something happens with the boiler afterwards, you have no warranty.

Your idea for how to do it, is quit good. Just remember that anything under pressure can be dangrous and you should take precautions when doing this. Would recommend you to get in done by certified personel, however if the testing is only for your own interest it can be done by your self.

I would not recommend you to use a pressure washer for this job, use a hand pump that can reach your desired pressure. Be shure not to stand to close when you test it, use a pipe or hose that can take the pressure between the pump and boiler. I know RIDGID has hand pumps for pressure testing, they are ok.

I would hold the pressure for minimum an hour.

I would again recommend you to get this done by certified people, then you would be the one blamed if something goes wrong.

 

[metengr]

We will need to hydrotest the boiler. We have the option of doing it ourselves or having the boiler service company do it for us. I have never done this before and I am looking for some advice.

Have the boiler service company perform this activity.

 

[1464649]

myrdale,

Depending upon your location you may be required to have a State Boiler Inspector witness the hydro of a new boiler. This is the case in MN and I assume other states as well. This is typically based on 1.5 x MAWP.

You should have the boiler completely full of water (no air at all), all valves should be closed and all valves should be verified that they can handle the test pressure. Sometimes water column and other small valves are not rated for much beyond the boiler MAWP and may leak or be damaged so verify these device ratings. You'll also need to blind off or gag your safety valve(s).

We have used pressure washers with success but be ready to shut them off or isolate them as the pressure can climb very fast.

I would recommend having an experienced person perform the hydro as there are dangers involved, especially if you have any air pockets.

 

[MAPower]

myrdale,

Definately have the boiler manufacturer perform the hydrotest.

After they have performed the test and as years pass, you and your team can perform the test. I've seen this done routinely to test tube leak repairs. It is not uncommon. But for a new boiler it needs to be the boiler manufacturer.

 

[Unotec]

You've never done it before, but for a couple grand, I'd go the safe way and have the boiler company do it.

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[BenjaminM]

Thankyou all for the advice and responces!

The boiler company quoted us $700 for the hydrotest, assuming we had everything buttoned up and ready to go. My boss has decided we will be doing the hydrotest ourselves though.

It's an odd situation but we were reciently purchased by another chemical manufacture here in town. I've talked it over with their engineer, he's done hydrotest before and has offered to help out. Our maintenance guy and myself are much relieved.

I will let you all know how it goes.

 

[BenjaminM]

We completed the hydrotest this morning. It went very well.

After evacuating all the air, we initially pressurized the boiler to 70 PSI with a hose connected to a city water tap.

We then continued increasing the pressure to 190 PSI (1.5xMAWP) with a simple pressure washer. We had three 3/4" ball valves set up as a double block and bleed. Slightly opening, then closing the valves allowed us to step up to 190 PSI with out issue.

After several minutes we dropped the pressure down to 125 and held for an hour.

Seven of the tube sheets did have some minor leaking around where they were rolled. This weeping disappeared completely when we dropped the pressure to 125 PSI.

Once running and up to temperature, at our lower pressure we are doubting there will be any leaks at all. We are planning to consult with the boiler serivce company as to if we need to have these tubes re-rolled though.

Is there any amount of leaks that are considered typical or acceptable in general? We've had to replace refactory and tubes from a previous leak in our current boiler before.

 

[unclesyd]

I'm going to throw this out here and may get hammered, but it concerns me that you took the pressure to 1.5 MAWP (190 psig) on an old boiler.
It is our policy with concurrence of all concerned parties that any boiler that has been in service be pressured tested to no more than 110% of the MAWP. We adhere to this procedure on our power boilers (6) and all Therminol vaporizers (8) just to prevent occurrences such as the weepers you experienced and other bad things.

 

[MJCronin]

I am very much interested in "unclesyd's" comments and his 110% rule

Considering that there are so many boilers out there and that "secondary hydros" are a quick and complete way to check the work done.......does someone have a code, guideline or standard on this issue ?

What should be the pressure setpoint for the hydrotesting of equipment that has been put into service ?

100% of MAWP...110% of MAWP or what ??????

I am sure that this question has come up many, many times before..

-MJC

 

[1464649]

I wouldn't be concerned about a few weeping tube to tubesheet connections, especially at 150% MAWP. We regularly hydro boilers at around 80% MAWP after repair work and sometimes see weepers that will disappear as soon as the boiler is fired up and the tubes are allowed to further expand into the tube sheet holes.

With regard to the 110% rule, in my experience it's always been a group decision including the operator/owner, insurance inspector, possibly the state boiler inspector, and repair contractor as to what a safe test pressure should be.

We recently re-tubed an economizer with a MAWP around 975 psig. The engineer's specification called for a 150% hydro, which we were prepared to do, but the owner wouldn't allow it...the valves wouldn't have held and who knows what leaks we might have created. It was tested at 500 psig instead.

 

[2CRUDE]

to the OP, for future reference....
when in doubt, follow the code.
Section VII, C2.270.
check with your local AI to determine whether he has to witness the test and sign off on any documents pertaining to the hydro. it's a good idea to remove any fixtures that may be damaged by the hydro pressure and to use a hydro gauge that has been calibrated by a vendor with an acceptable QA program.
as for the 1.5X hydro, it probably isn't necessary. i have been involved in B31.1 repairs and only a few times have we gone up to 1.5X due to question of the integrity of the boiler as a whole or it's history.
weeping tubes are not good. if there is any leakage it should be a slight damp ring at most. anything more and i'd recommend a re-roll or roll and weld.
for a hydro pump, i recommend a low volume PD pump with an adjustable pressure relief device to recirc. you can find these at most rental stores.
cheers.

 

[metengr]

Hydrotesting an aged boiler to 1.5 X MAWP is not something I advocate, and in fact, we will not do not do it on large Power Boilers. Most parties view the hydrotest as some type of belt and suspenders approach to assuring a boiler can continue to operate for another "x" years.

This is absolute false thinking on aged equipment. All the hydrotest will do is to confirm you have a leak at this moment in time, it does nothing to assure long term boiler reliability and will not provide any benefit as one would obtain for new material - for example local strain hardening that is done on a new boiler hydrotest. Once a hydrostatic test has been performed, a second test at some point down the road does nothing for redistribution of stresses.

So, if you want to check for leaks perform a static fill or low pressure squeeze and that is it. To assure long term boiler reliability rely on condition assessment activities during scheduled major boiler outages.