Temporary Repair Cracked Flange
Temporary Repair Cracked Flange
(OP)
Dear all,
I have a few heat exchanger flanges found cracked possibly due to over-torqued and victim of hydrogen sulfide stress cracking, the operating temperature is between 45 to 129 deg C.
I can't shutdown the line for replacement, is there any ways to temporary repair these flanges and hold them for at least 1 year until next shutdown? Flange repair clamp sounds like a solution but I'm afraid it will further damage the flange during fastening..
Wish I can have more suggestions...
I have a few heat exchanger flanges found cracked possibly due to over-torqued and victim of hydrogen sulfide stress cracking, the operating temperature is between 45 to 129 deg C.
I can't shutdown the line for replacement, is there any ways to temporary repair these flanges and hold them for at least 1 year until next shutdown? Flange repair clamp sounds like a solution but I'm afraid it will further damage the flange during fastening..
Wish I can have more suggestions...





RE: Temporary Repair Cracked Flange
Pressure, temperature, operating fluid, pipe metal, flange metal ... Are what?
RE: Temporary Repair Cracked Flange
I recall they have techniques, clamps and things to sort most things.. http://www.furmanite.com/
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Temporary Repair Cracked Flange
Furmanite is one of my consideration, they do offer repair clamps for flanges, but I just need to make sure if this is a good method. According to our corrosion engineers and also vendors, repair clamps are unable to assure a minimum warranty for "cracked" flanges, they can install it for such repair but couldn't guarantee the warranty period. I need something that can temporary reinforce it at least for 12 months until next shutdown, sorry I was unable to provide photo but the cracking is quite severe and extended to the bolt holes..
Has anyone having experience of repairing such cracked flanges?
RE: Temporary Repair Cracked Flange
RE: Temporary Repair Cracked Flange
Carbon steel is a ductile material...... and substitution of CS for CI is a common solution
MJCronin
Sr. Process Engineer
RE: Temporary Repair Cracked Flange
Managed to get some photo from my inspector from offshore, please see the attached.
Perhaps you guys can take a look and give some suggestion?
RE: Temporary Repair Cracked Flange
For me I would simply clamp it with two half shells around the flange outer circumference.
I don't know what the crack mechanism here is, but SCC seems unlikely in this location. That would require some force to split that unless there is a material fault.
Seems a thick flange for 10 psi(a?) - is this under vacuum?
how far does that crack go? Picture from underneath would be good.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Temporary Repair Cracked Flange
The crack goes quite deep and almost reaches the bolt..
If putting on 2-half-shell clamps or split sleeve repair clamps on the flanges, will it actually causing more stress to the cracks and eventually rupture the flange? My vendor could not give any better justification because not even them dare to give any warranty of at least 1 year.
Another concern is if putting on repair clamp, what will be the recommended tension/torque for the clamps' bolting? The clamp will be secured from outside the flange, over-torque will definitely causing more cracks on the flange, and insufficient torque will make no difference to the repair.. I don't prefer welding on the repair clamp because we need to frequently monitor the flange, and by bolting is able to tighten more flexibly..
RE: Temporary Repair Cracked Flange
There is very little circumferential force on the outside of a flange so any external ring clamp clamp is simply there to stop this crack getting any bigger.
how would the flange "rupture"? When you initially said crack I though this was in the shoulder of the weld or otherwise on the parts inside the bolt circle.
"warranty" will scare off most vendors for something like this. You can only try something and monitor the crack regularly for any changes.
You could just cut a channel in from the outside to the bolt and create a slot. This part of the flange is only really holding the bolts in place and providing a bit of metal for the bending moment caused by the bolt tension, but cutting slots in a flange has very little impact on the strength of a flange.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Temporary Repair Cracked Flange
You are right, when I am asking for warranty, all of them back-off from my request..
May I know what do you mean by cutting a channel in fro the outside to the bolt to create a slot? I am sorry I don't get what you mean...can you please kindly explain in more detail?
RE: Temporary Repair Cracked Flange
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Temporary Repair Cracked Flange
As it seems from the stamping on the flange at your pictures, this NPS 12" RTJ flange is made of 304 stainless.
I wouldn’t consider the austenitic stainless steel (300 series) as the best choice for offshore environment……
Cl-SCC usually occurs at above 60°C (and more likely under wet insulation).
RE: Temporary Repair Cracked Flange
Bro shmulik, it is not SS304, SS304 definitely not be suitable in offshore.
You had a point just like MJCronin, CI will be the victom for such cracking occured, and yes it is under wet insulation (it is HX). I will have to check with the inspector once again because the inspection report is presenting it as CS.
RE: Temporary Repair Cracked Flange
RE: Temporary Repair Cracked Flange
RE: Temporary Repair Cracked Flange
Nevertheless thank you very much for correcting me Bro Shmulik.
Trying to convince my boss of using the repair clamp right now..
RE: Temporary Repair Cracked Flange
Anything that you do will shift stresses and result in new cracks.
You could make new split rings to put on the outside of both faces, but what about where the flange attaches to the body? Are there any cracks there?
What is the damage/liability when one of these completely fails?
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Temporary Repair Cracked Flange
More significant than the grade stamped on the flange - what is the country of origin?
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"
RE: Temporary Repair Cracked Flange
There are no cracks at other part, but only on the flanges, double confirmed with inspector offshore. X-ray Fluorescence will be a good suggestion to be first conducted on the flange, then we will move to next step, eg using repair sleeve or etc..
RE: Temporary Repair Cracked Flange
What does country of origin matter ? - if it is faulty it is faulty no matter where it is from.
And it may not even be faulty, it may just be the totally wrong material in the wrong environment.
simonmagsucang,
I have to agree with edstainless - you have major cracking and you have no idea of the full extent.
Is it only cracked from the outer edge to the bolt hole or has the crack propagated further into the internals of the connection ?
It appears the "bean counters" have said it can't be shut down for 12 months - you need to get someone a lot higher up the food chain than yourself involved (your companies Welding Engineer for a start).
You should not be looking for "fixes" on an internet forum - I am pretty sure there will be serious consequences if these flanges fail, just to save a few dollars in lost production.
Good luck with what you are trying to do but remember rule number 1 - CYA
Cheers,
DD
RE: Temporary Repair Cracked Flange
So far the cracks only be seen outside thw flange, the agenda is we might probably temporary shutdown the Glycol HX for a while in the next few days to have a full inspection, if it has cracks at the internal connection we will have to go for replacement of the flange which we have to go for higher authority to urge for pausing the production before worse thing happens.
If it doesn't crack at the internal connection, we might go for flange split repair clamp, and then find a suitable window to have it replaced in 3~6 months time rather than wait for the next shutdown (12 months).
I had repeatedly highlighting this issue to the production team and finally HSE and the facilities engineers will be conducting riSK assessment soon.
RE: Temporary Repair Cracked Flange
RE: Temporary Repair Cracked Flange
Don't worry, it will survive, but they can't write down warranty, since the current situation is pretty bad, and any upset will jeopardise their warranty. You need to replace the flange and propbably whole manifold as soon as possible.