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Up Topic Welding Industry / Inspection & Qualification / Hydrostatic test of pressure vessel
- - By Joey (***) Date 10-04-2008 08:23
we done hydrotest on pressure vessel designed in accordance with ASME VIII Div 1 2007. The old guys in the workshop applied the pressure based on x1.5 of design pressure instead of x1.3 of the current requirement. If the hydrostatic test procedure didn't state the max test pressure allowed, then what would be the max limit? what is your opinion? I could not find the answer in ASME VIII.

Best Regards
Joey
Parent - By Ariel D C (**) Date 10-06-2008 13:09
Hello Joey

you may want to raise this issue to the PV Engineer for advice. API 510 states.........At ambient temperatures, carbon, low-alloy, and other ferritic
steels may be susceptible to brittle failure. A number of failures have been attributed to brittle fracture of steels that were exposed to temperatures below their transition temperature and to pressures greater than 20 percent of the required hydrostatic test pressure.

Ariel D C
Parent - - By G.S.Crisi (****) Date 10-06-2008 23:46
The current requirement of ASME VIII for hydrostatic test is 1.3 times the design pressure. The "good old guys" ran the test at 1.5 times the design pressure, because they've made like that their whole life. The vessel passed the test. Fine !
I can't understand what your problem is.
Giovanni S. Crisi
Sao Paulo - Brazil
Parent - By michael kniolek (***) Date 10-07-2008 00:08
Crisi
Is there anymore the the calculation to find the test presure? If i have my max allowable workin pressure is it 1.3 times with no other considerations?
vessels designed for internal pressures shall be subject to a hydro test pressure which every point in the vessel is at least 1.3 times the maximum allowable working pressure to be marked on the vessel (crisi could you explaine the following) to me.............
multiplied by the lowest ratio (for the materials being used) of the stress value S for the test temp on the vessel to the stress value S for the desighn temp.
Where would i find the latter infomation? (stress value) and is that part of the calculation?

i was told to Write down S test (at the test temperature) and Sservice (at the service temperature). Divide them, so you get a number >=1. Do it for each detail of pressurised stuff. Choose the smallest number. Multiply this number by your MAWP and by 1.3. That's your (minimum!) test pressure value
MDK
Parent - - By Joey (***) Date 10-07-2008 01:16
If the hydrostatic test procedure didn't state the max test pressure allowed, then what would be the max limit? I could not find the answer in ASME VIII.

my problem is the max limit, which you didn't answer. Unlike Ariel D C who at least highlighted the 20 percent of test pressure.

Best Regards
Joey
Parent - By RANDER (***) Date 10-07-2008 02:08
Joey,
Read thru UG-99 with attention to para (d).
This division (section VIII) does not specify an upper limit to hydrostatic testing pressures however if over pressurization occurred which resulted in visible permanent distortion the Inspector has the right to reject the vessel
Parent - - By Noel Tan (**) Date 10-07-2008 03:34
Joey,

I think something is not right, since we are not going to do any pressure testing at temperature below or even close to transition temperature.
Brittle failure at 20% of test pressure might not be a concerned on new PV. Unless old PV had gone through temper embirttlement.

As highlighted by RANDER. When the PV having permenant distorsion after pressure testing, the AI has the right to reject the PV.
Considering maximum allowable stress "S" used in the calculation is about 2/3 of the material's minimum yield strength. it means when we tested it to 1.5times the
design maximum allowable pressure, it should not produce any permanant distortion.
(Just considering material always having actual yield strength higher than the required, and the formula for maximum allowable pressure/ minimum required thickness "-0.6P" is another kind of safety factor, also we might sometime having some corrosion allowance)

When tested somewhere above 1.5times or exceed the yield strength of the construction material, it might have a chance to produce permenant distortion.
that is why it is not the same for different PV.

Please correct me if i'm wrong.

Regards,
Noel Tan

  
Parent - - By Joey (***) Date 10-07-2008 05:49
Thanks for your reminder on deformation issue during hydro test. All I need to know is your "opinion" on the max limit as precautionary measure.

Best Regards
Joey
Parent - - By Noel Tan (**) Date 10-07-2008 07:43
Joey,

I think you do not understand my reply, i means the code does not allow the PV to have permanant deformation after hydro testing it means the test pressure shall not produce any stress level above PV material's yield strength. if you know how to calculate that, please do it. otherwise use your eyes to visually inspect it after hydrotesting whether the PV is permanantly deform or not.

Regards,
Noel
Parent - - By Joey (***) Date 10-07-2008 12:29
Noel,

deformation is not the issue I want to know. I do not want to calculate as well. All I need to know is opinion on max limit, which at least I got some good info about the 20% based on API510, which may or may not be applicable to my current job and which doesn't matter to me.

since you are hot in deformation, can I ask you? do you think visual inspection alone is enough to determine the deformation? why don't you advise other method if you're very concern on deformation. And why you didn't consider to advise me to review the design calculation and to check how much the corrosion allowance or manufacturer thickness allowance given., and whether the nominal thickness of PV can withstand the exceeded pressure.

Best Regards
Joey
Parent - By RANDER (***) Date 10-07-2008 14:27 Edited 10-07-2008 16:34
If opinion is what you want then you need to bring the issue to your engineer or client and get their opinion.  The code states no Max limit.  That is the codes stance. 
Parent - - By G.S.Crisi (****) Date 10-07-2008 21:17
What I don't understand is this: if your vessel has already passed the hydro test with a test pressure of 1.5 the design pressure, what are you bothering about?
Giovanni S. Crisi
Parent - - By Joey (***) Date 10-08-2008 01:14
Giovanni, our safety auditor is not happy on why the 1.3 requirement was not followed and still using the 1.5. It's a non compliance and the hydro test procedure requested to be revised to reflect the max limit.

RANDER, Thanks for confirming code states no max limit. 

Best Regards
Joey
Parent - - By G.S.Crisi (****) Date 10-08-2008 20:19
If the tank passed the test at 1.5 times the design pressure, it's more than obvious that it would have passed also at 1.3. The test has been already carried out and it's impossible now to come back in time to cancel it and make another one. 
What you may do is to beg the safety auditor pardon and swear before him (nor forgetting to put your right hand onto the Bible) that never again you'll run a test at 1.5 the design pressure. That will make him happy (I hope)
Giovanni S. Crisi
Parent - - By Joey (***) Date 10-09-2008 08:15
Giovanni S. Crisi - if you want to make fun, please don't use the "Bible".

Parent - - By G.S.Crisi (****) Date 10-09-2008 19:37
You see, Joey, we're from different countries and therefore different customs. It often happens that something that is an innocent comment in one country is regarded as very offensive in another one.  
Although not a Christian, I'm a religious person and I would never allow myself to make offensive jokes on somebody's else religious beliefs.
Here in Brazil, the expression "to swear with the right hand onto the Bible" is by no means offensive. It's used also by devote catholics. It means that you're telling the sincere and absolute truth.
In any case, I beg your pardon if I made you to feel uncomfortable with my posting above; it wasn't my intention.
Giovanni S. Crisi 
Parent - - By johnnyh (***) Date 10-09-2008 19:57
No one was offended by that comment except Joey.  He woke up on the wrong side of the bed this morning and decided to get on the forum and aggravate some folks.  He tried to get me fired up but I was in too good of a mood.
Parent - - By Joey (***) Date 10-10-2008 02:04
Mr John H

I hope you are not representing the mentality of all people involved in this forum.

Anyway, I have nothing to prove to impress you. If you think that it's common practice in Texas to swear with the right hand onto the Bible in your profession as CWI with API 510 cert at the time of your work, then that's fine. My suggestion to you (if your are a Christian) is to handle with care the bible, provide a good cover for protection so that the Bible wont get wet & dirty while you carrying it at the worksite for swearing purposes. 

Best regards

Joey
Parent - By RANDER (***) Date 10-10-2008 02:23
Joey,
I believe Mr. Crisi was not speaking literally when he said to place ones hand on the Bible.  Also as a safety precaution and to avoid over pressurization of your vessel you might consider installing a pressure relief valve set to pop at no more than 10% over your test pressure when hydrotesting.  I realize this will not prevent your shop guys from testing to 1.5X MAWP if they believe that to be the correct pressure however it is common practice and may lower your safety guys blood pressure. 
Regards,
RANDER
Parent - By johnnyh (***) Date 10-12-2008 04:32
You're right, there is no need to impress me.  It was a figure of speech.  As Christians we tell the truth.
Parent - By Joey (***) Date 10-10-2008 02:13
Professor Giovanni S. Crisi

Since it's a common practice in Brazil, then I'm okay with your above posting.

You're a Professor, hope your comments will serve good lesson to your students reading this forum.

Keep it up.

Joey
Parent - By jwright650 (*****) Date 10-10-2008 11:19
Giovanni, I agree with your comment, to say that someone would swear on a Bible or a stack of them, is to say that you mean what you say with the utmost sincerity and truthfullness. The court system here used to use a Bible for the plantiff, the defendant and any witnesses to swear on before giving testimony to tell the truth, the whole truth, and nothing but the truth so help me God......but they have strayed far away from that today.
Very well said. Nothing offensive to me in that statement at all. I believe the Bible is the "infallible" Word of God and I hold the utmost respect for what it is and stands for.

http://dictionary.reference.com/browse/infallible
Parent - - By Joseph P. Kane (****) Date 10-13-2008 14:16
Giovanni -Joey

I second the comment that no one was offended by that use of the word bible, except someone with a chip on his shoulders.

You should withdraw your apology.

Joey;  You owe everyone an apology for making that stupid insensitive phony comment!

Joe Kane
Parent - - By Joey (***) Date 10-14-2008 02:38 Edited 10-14-2008 04:42
Sir Joseph P Kane, your honor please let me explain, I did not know that Prof Giovanni is serious by mentioning to swear with the right hand onto the Bible. The topic of discussion is just a simple hydrotest issue and I felt uneasy that he included that sacred word and I thought that he is trying to be funny.

In your other profession as welding consultant, do you advise the use of bible at steel workshop to take oath? Do you suggest the same to you clients, especially when their welders used the wrong electrode? I have not read this practice in any code, standard or other recommended practices or in any contract specification. I have not seen anyone at fab shop or erection site that people using the bible and asking someone to take oath or swear.

That's the reason why I said " if you want to make fun, don't use the bible" do you think it's a stupid comment!!!!, your highness, there are many inspectors reading this forum, please conduct the trial impartially.

Adios

Joey
Parent - By hogan (****) Date 10-14-2008 14:00
Joey,
It is a common saying in America. You should not get bothered by American customs on an American forum.
Parent - By G.S.Crisi (****) Date 10-16-2008 21:04
Joey,
I'll tell you for the second time. You live in Asia, I live in South America. There are 180º of Earth globe between us. When in your place is mid day in mine is midnight. So, no surprise that there are quite different customs in our countries.
Here in Brazil, when one says "I can swear it with my hand onto the Bible", he's meaning that he's telling the absolute truth and no one feels offended because of it. It's just an expression and also devote catholics use it. Therefore, it wasn't my intention to be funny nor offensive, and even less to cheat a book that Christians consider sacred. (I'm a religious man, but not a Christian).
In English language there's an expression: "It's raining cats and dogs". Does someone think that there are actually cats and dogs falling from the sky and dropping on the heads of people?
Giovanni S. Crisi   
Parent - - By bert lee (**) Date 10-15-2008 12:33
Joe

Bible may not be suitable to others who have different religion. By using word bible for swear will be sensitve and offensive for our friends in middle east.

regards
bert lee

Parent - By 803056 (*****) Date 10-15-2008 14:34
Take a powder!

Al
Parent - By Joseph P. Kane (****) Date 10-17-2008 00:12
"Friends in the Middle East"??!!??!!??!!??!!??

Now, that is either  a subtle oxymoron, or  political propaganda newspeak!
Parent - - By tare Date 10-31-2008 20:10
Profesor Giovanni, podria ayudarme con un tema.

Como se puede estimar el volumen de Argon que se va utilizar para realizar una soldadura por proceso TIG. Sabemos cual es el díametro y el espesor y queremos estimar el volumen de argon necesario

Existe alguna relacion estimada entre el volumen de Argon consumido y el volumen o peso de material depositado

saludos
Parent - By G.S.Crisi (****) Date 11-03-2008 21:51
Sí, existe, pero no la tengo a mano en este momento.
Es una información que suele estar en los catálogos tanto de gases de protección cuanto en los de varillas para soldadura TIG y alambres para soldadura MIG.
Otra posibilidad es clicar en Search ahí arriba y donde dice Keywords escribir Argonium consumption para ver si sale algo (casi seguramente saldrá)
Buena suerte
Giovanni S. Crisi
Up Topic Welding Industry / Inspection & Qualification / Hydrostatic test of pressure vessel

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