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- - By qaqcmpm (*) Date 10-02-2008 08:24
#150 flange required 30bar- hydrotest & #600 flange required 110bar-hydrotest; if both are connected in a same piping spools have i to test at lower or higher pressure (code of construction B31.3)
Parent - By jon20013 (*****) Date 10-02-2008 08:44
In my opinion you would be required to test to the greater pressure.  You may want to discuss with system engineer to determine whether any special precautions may be necessary.  If these parts one the same line, your design should indicate a designated pressure?
Parent - By 3.2 Inspector (***) Date 10-02-2008 09:47
The pressure should be calculated according to flange rating since the flange is more likely to fail due to the geometrical shape of the flange, where the pipe is straight and uniform in its shape.

3.2
Parent - By CWI555 (*****) Date 10-02-2008 12:23
Unless I am sadely mistaken, The system/spool itself is what your pressure should be based on. The flanges themselves should have been (and as you have stated) rated from the manufacture. If someone put a flange in the system that is not rated for that system, you have bigger fish to fry than worrying about the individual flange ratings.
Parent - - By TimGary (****) Date 10-02-2008 12:29
You should hydrotest to 1.5 times the design pressure of the system, unless the scope of work says differently.
The only reason to worry about the individual flange ratings is if they fall below this sum.

Tim
Parent - By 3.2 Inspector (***) Date 10-02-2008 14:14
Someone rated your reply with 3 stars.
But IMO (and ASME's opinion, you are wrong)

3.2
Parent - - By new tito (***) Date 10-02-2008 12:43
This may be a situation where the OP may not have access to an engineer, or even possibly no engineering involvement at all.  This had been my case many times, however, we do have a company spec that states process piping shall be hydrotested 1.5 times the working pressure of the weakest link, which is usually the flanges.  In the cases of 1 spool piece with 2 different flange ratings, we test to the lower flange rating.
Parent - - By jeffww88 (*) Date 10-02-2008 13:02
So, can someone please educate me on this.  What code are you working to that has you testing based on flange ratings rather than system design?  I have never came across this and am always looking for a learning opportunity.

Thanks,
Jeff
Parent - - By Shane Feder (****) Date 10-02-2008 13:24
Hello guys,
As noted previously the flange ratings are irrelevant to the hydrotest pressure.
It is based on testing 1.5 times the design pressure of the system.
Hypothetically, an engineer may (with a serious drink/drug problem) nominate 150#, 300#, 600# and 900# flanges in the same piping system but that has no bearing on what the design pressure is and therefore no bearing on the hydrotest pressure,
Regards,
Shane
Parent - By 3.2 Inspector (***) Date 10-02-2008 13:49
It is based on testing 1.5 times the design pressure of the system.......oh really?

Hypothetically, an engineer may (with a serious drink/drug problem) nominate 150#, 300#, 600# and 900# flanges in the same piping system but that has no bearing on what the design pressure is and therefore no bearing on the hydrotest pressure,

But ofcourse when he determine the test pressure his drinking/drug habbit has no influence?

3.2
Parent - - By NDTIII (***) Date 10-02-2008 13:51 Edited 10-02-2008 14:05
B31.3 Paragraph 345.2.1 and 345.4.2(c) state, "If the test pressure would produce a nominal pressure stress or longitudinal stress in excess of yield strength at test temperature, the test pressure may be reduced to the maximum pressure that will not exceed the yield strength at test temperature".

What I would recommend is test the pipe first, if it wasn't already tested at the mill. Then test it after welding each flange at the flange rating. Alternativley you could get the client's permission to test the spool at 30bar and do 100% RT or UT.
Parent - - By 3.2 Inspector (***) Date 10-02-2008 13:55
That tells me you would test the spool at 30bar......For the part with the 150 flange, yes I agree.
Then I would do another hydro for the part with the 600 flange.

Then I would perform 100% radiography or UT......For which reason?

3.2
Parent - - By NDTIII (***) Date 10-02-2008 14:02 Edited 10-02-2008 14:07
OK Why would you do the 30 bar test first and then test then 600# flange? That defeats the purpose. You would do the lowest test last.

Why 100% RT or UT. Because it would give the owner a bit more confidence in your work. That's all. Only a suggestion. Why do you have to quote everything verbatim and question everything? What is it with you 3.x guys?
Parent - By 3.2 Inspector (***) Date 10-02-2008 14:12
It's a bit easier, people can actually see what I question or answer to.... in this post I will try not to.

I dont understand what you mean

One of the reasons to do a hydro test is also to see if the material can withstand pressure.

I don't know, since you are a 3.x guy yourself, you can answer that as well as me.

3.2
Parent - - By raftergwelding (*****) Date 10-04-2008 04:35
you have a 150# and a 600# flange on the same sool why not test it to 750#s and be done with it i'm not an inspector but makes sense to me
Parent - By 3.2 Inspector (***) Date 10-04-2008 07:06
If - some some reason - you have different flanges in the piping system, you test according to the lower rating, as the piping system later on will not be allowed to exceed the MAWP for the lowest rated fitting/flange.

3.2
Parent - - By TimGary (****) Date 10-04-2008 15:11
Hey Shad,

Think about it man.
If you hydro a 150# rated part to 750#, don't you think it will fail before you get to 750#?

Drinking and posting is dangerous!  :-)

Tim
Parent - By raftergwelding (*****) Date 10-04-2008 19:12
1st i was drinking 2nd the og said he had a 150 and a 700 on the same spool so it made sence to me in the past i have seen 600# flanges on spools that were tested at 1,000 psi and they passed so yes it made sense to me but i'm not an inspector or tester
Parent - - By 3.2 Inspector (***) Date 10-02-2008 13:47
It happends every day - all over the world.
It has several benefits, such as the owner can use the piping systems for other applications later on, which has a different working pressure.

What code are you working to that has you testing based on flange ratings rather than system design?

I dont think there is any codes that require it, however many owners choose to do it.

Keep in mind that the ASME B31.3 requirement of 1.5 times design pressure, is a minimum.
In case the design temperature is above test temperature the test pressure has to be calculated.

3.2
Parent - - By NDTIII (***) Date 10-02-2008 14:12
No it only happens in your little world.
Parent - - By NDTIII (***) Date 10-02-2008 14:16
I am finished talking to you. You are unbearable. Don't speak to me or reply to my posts anymore. Doesn't the fact that you were banned once tell you a little something about yourself? How may times did you have to take the test to pass your 3.2?
Parent - By 3.2 Inspector (***) Date 10-02-2008 14:27
I passed the first time, hell, I have passed all my tests the first time, which is irrelevant as theese test basicly only test your short time memory.
Am I unbearable because I has different oppinions than you?

3.2
Parent - - By 3.2 Inspector (***) Date 10-02-2008 14:16
I have very recently done jobs in Statoil Hydro and ExxonMobil plants.
Both places tested at full flange rating.

3.2
Parent - - By NDTIII (***) Date 10-02-2008 14:18
Yes but you don't test a 150# flange with a 600# flange at the 600# flange rating. ou would either reduce the test pressure to 30 bar or test them seperately.
Parent - - By 3.2 Inspector (***) Date 10-02-2008 14:23
I said that I would do ANOTHER hydro for the spool with the 600 flange.
I did not think that could be misunderstood.....Guess I was wrong :)

I will first do a hydro on the spool with the 150 flange at 30 bar, then I will take the spool (separated from the spool with the 150 flange) with the 600 flange and do a hydro at full test pressure.

3.2
Parent - - By NDTIII (***) Date 10-02-2008 14:26
You raise my blood pressure above my yield strength. Why don't you just speak to the guy who posed the queston directly and answer him straight. He is probably confused now. He only wants to know what he should do. That is the purpose of this forum., Not  arguing.
Parent - By 3.2 Inspector (***) Date 10-02-2008 14:34
Then you has become plastic deform :)
I did answer the guy straight, and my answer was: Do a hydro according to flange ratings. Understand this: That was MY opinion.
Other people has different oppinions, some is right, but others are wrong.

In most cases the pressure has to be calculated, and not just 1.5 x design pressure, if you test at full flange rating you dont need to worry about all that, AND you can use thi piping system for other applications as well, granted the material is suitable for the application.

If that makes me unbearable, oh well.

3.2
Parent - By Joey (***) Date 10-02-2008 15:08 Edited 10-02-2008 15:22
3.2

you did mention the places you've worked, are you referring to the following?

Hydrostatic leak test pressure shall be determined per the applicable code but shall be at least 100 psig (690 kPa), except as follows:

1)  For ASME B16.5 material groups 1.1 through 2.5, the test pressure for Class 150 piping systems up through size NPS 24 shall be equal to 1.5 times the working pressure of Class 150 flanges at 100degF (37degC).

2)  Test pressure for Class 300 piping systems for ASME B16.5 material groups 1.1 through 2.5 and up through size NPS 24 shall be set equal to the lower of:
a)  1.5 times the working pressure of Class 300 flanges at 100degF (37degC)
b)  1.5 times the maximum pressure rating of the limiting system component at 100degF (37degC).  Where a system component limits the maximum working pressure of the piping system, consideration shall be given to isolating the limiting component from the test circuit so as to allow for an increase in the test pressure.

*******
however, as inspector, it will be much easier for me to apply the test pressure stated on isometric drawing which has been approved / endorsed by the piping engineer.

Best Regards
Joey
Parent - - By raptor34 (**) Date 10-03-2008 01:03
How would you test it if the 150# flange was welded directly to the 600#?
Parent - - By 3.2 Inspector (***) Date 10-04-2008 07:09
According to the 150 flange.

3.2
Parent - By raptor34 (**) Date 10-04-2008 22:59
So doesnt that answer your question about how you say it should be done?
Parent - By cremx (*) Date 11-29-2009 04:58
3.2 the drugs destroy you
Parent - By 3.2 Inspector (***) Date 10-03-2008 05:12
It looks like RANDER is living in the same little world as me.

It's a small world as they say....

3.2
Parent - - By dbigkahunna (****) Date 10-02-2008 15:49 Edited 10-02-2008 15:52
This is an answer based on API 570 for Pressure Piping
I am guessing this is has a 150# on one end of the spool and a 300 or 600# on the other. Such as as at a 300# control valve going into a 150# system.
First you will need to know the pressure rating of the system. Then you will need to know if there has been any de-ratings due to corrosion. While you test for the piping system, you cannot exceed the hydrotest ratings of the flanges. While the pipe may hold 2800 psi, you would not test it to 2800 with 150# flanges on the end. Loss of containment may result
My call on it would be to hydro test to the 150# flange if it is attached to a 150# system. If it is attached to a 300# system, a piping engineer would have to make the call. If there are different flange series in the system, the the AI will need to make the call. Not the contractor
BABRT's
Parent - - By Shane Feder (****) Date 10-03-2008 01:07
Hello guys,
My apologies for my earlier posting, I had consumed a few too many rums.
However, I am still confused over what a flange rating has to do with the hydrotest pressure.
If a design pressure is less than 1035 kpa then the system falls into Category D piping and as such does not need a hydrotest (at the owners discretion). If the designer/s have decided to put 300# flanges in the system for whatever reason (maybe for a 300# valve) would you have to test to 300# rating ?, No.
The designer designs his system to a certain pressure ensuring that the piping materials, fittings, valves all meet the minimum pressure requirement. Then the piping system is tested to 1.5 times the design pressure (minimum) irrespective of what fittings have been installed in the system.
Am I missing something here ?
Regards,
Shane
Parent - - By RANDER (***) Date 10-03-2008 01:17
Shane,
Drinking and posting is almost as dangerous as drinking and driving!
That being said Ive had a few 7&7 myself so take this for what its worth. ....... . .... ...
I have worked for refineries in North America who routinely hydrotest piping systems built to B31.3 to full flange rating instead of 1.5 X design pressure.  Why you ask?   I dont know.....I wasn't in those meetings and never asked....but it is done everyday. 
Parent - - By dbigkahunna (****) Date 10-03-2008 02:51
The piping design should take into account the flange rating. On pipelines the hydrotest can be up to 100% of the SMYS. In this case the flanges must be able to withstand this pressure.
BABRT's
Parent - - By Nanjing Date 10-04-2008 03:00
It can be either. If you pressure test using the flange rating you are just testing at the maximum allowable pressure for that flange and this does not take into account the actual service conditions of the line (which will be lower as the designer selects a flange at the correct rating).If you have for some reason flanges with two different pressure temperature ratings then you would have to test as per the lower class.
Parent - - By NDTIII (***) Date 10-04-2008 03:53 Edited 10-04-2008 04:08
I'm sorry gentlemen but I think we were getting a little confused and off track here. Seems to be the norm lately.
Nanjing, bdickkahunna and Rander are all correct, I believe.  And Shane is right in having a drink before entering this site these days.
The test pressure has nothing to do with the operating pressure or service conditions of the piping system per B31.3. It is based on the yield strength of the piping system. However when flanges are designed into the system, the flange rating becomes the limiting factor in pressure testing.
Therefore, if the designers use A106 Gr B pipe, for example, which let's say, for the sake of not arguing, has a yield strength of about 60,000 psi. I'm not sure if that is correct or not, and let's say they design 150# flanges into the system, which have a lower rating than the pipe, then the flanges become the limiting factor of that system for pressure testing. Same applies to valves.
If you have a 150# flange in a system and the test pressure is 30 bar per ANSI, then you test that system at 30 bar and not 90% of the yield strength of the pipe. The pipe can be tested seperately if so desired. Should be done at the mill anyway. Depends on the purchase order.
Now if you are installing API-6A or 6B flanges or valves then you have to consider the working pressure and base it on that.
However, the original question references B31.3, so ANSI would apply and not API, and if the 150# flange is welded on the spool piece the the test pressure would be 30bar, no matter what other flanges are installed. The intent of B31.3 is to test the pipe at 1.5x the design pressure, but they understand you can't overpressurize any part of the system and if 150# flanges are designed into it then the 1.5x the design pressure becomes useless.
Someone please correct me if I'm wrong. I'll be at the bar. Just have me paged.
Parent - - By ctacker (****) Date 10-04-2008 04:21

>bdickkahunna


hope that was a typo, or you know something we dont? :) :) :)
Parent - - By Joey (***) Date 10-04-2008 07:52
forgive me but some responses are not easy to understand, my simple understanding will be ""the hydrostatic test pressure at any point in a metallic piping system shall not less than 1.5 times the design pressure"".

Best Regards
Joey
Parent - By 3.2 Inspector (***) Date 10-04-2008 08:34
Joey,
Forgive me for being part of the confusion.
You are right "the hydrostatic test pressure at any point in a metallic piping system shall not less than 1.5 times the design pressure"
The keyword here is "less" depending on the operating temperature, you might have to test it a greater pressure than 1.5 x design.

To my understanding you wont have all that hasle if you test it at full flange rating as you test to the maximum your chosen material can withstand.

I am not saying its the only way to do it, but it does have several advanteges as I see it.

3.2
Parent - By NDTIII (***) Date 10-04-2008 12:23
Yea sorry about that.
Parent - By 3.2 Inspector (***) Date 10-04-2008 08:12
Be carefull you dont confuse yield and tensile strength...

Yield strength is when the material has become plastic deform, typical with an 0.2% permanent elongation.
However, cracks can initiate even though the yield strength has not been exeeded - at notches, etc - the material yields locally, I think the english term is "fatigue"

Tensile strength is the maximum force you can apply before it breaks (UTS)

3.2
Parent - By 3.2 Inspector (***) Date 10-04-2008 09:03
Shane,

Sometimes you actually test piping systems with an operating pressure of 10 bar at 79 bar(LOL?)
One of the reasons to test according to flange rating is due to the shape of the flange, you install a fitting with a geometric "defect" which is not allowed as there is plenty of stress risers on a flange.

To my knowledge most codes dont take that into account.

3.2
Parent - - By 3.2 Inspector (***) Date 10-04-2008 08:41
As I am sure you know.....hydro testing can - at the inspectors discretion - be left out :)

3.2
Parent - - By Shane Feder (****) Date 10-04-2008 10:55
3.2,
I will stand by my original statement, flange ratings do not have anything to do with hydrotest pressure as per B31.3 (as the original poster asked), however, individual companies may require it as per their specifications.
A piping design engineer will design a piping system and he will decide what # flanges are required based on his calculations. The flanges / fittings nominated will be the minimum allowed as per the code so if he has 150# flanges nominated that is what the line will be rated as. If he has 300, 600, 900 or even 1500# flanges added in the line it doesn't change the fact that the system is only rated to 150# and therefore you will test it to that.
A piping system is only as strong as it's weakest link (eg. 150# flange) so why would you consider testing it to 300 or 600# when it is not designed for those pressures ?
Regards,
Shane
Parent - - By 3.2 Inspector (***) Date 10-04-2008 11:07
Shane,
I agree 100%, its not a code requirement
Well, actually I agree with your entire post.

I think I wrote somewhere, that if your have different flanges in the same system, you will either test the system seperatly or test it according to lowest flange rating, since the system cant be used at a greater pressure.

The original poster mentioned himself something about flange rating, thats why I keept on with that philosofi.

3.2
Parent - - By NDTIII (***) Date 10-04-2008 11:29
Please read para. 345.4.2(c) in B31.3. Although it doesn't specify flanges specifically, you can damage flanges by overpressurizing them.

"I think I wrote somewhere, that if your have different flanges in the same system, you will either test the system seperatly or test it according to lowest flange rating, since the system cant be used at a greater pressure."

That is a correct statement.

If a system is designed for a 150# flange thats all the pressure it needs. Pipe just comes with a higher yield strength. They cannot purchase pipe with the yield strength of a flange or valve.
Parent - By Shane Feder (****) Date 10-04-2008 12:34
#150 flange required 30bar- hydrotest & #600 flange required 110bar-hydrotest; if both are connected in a same piping spools have i to test at lower or higher pressure (code of construction B31.3)

Why oh why did it take so long to get around to a pretty basic answer to the poor guy who asked the original question ???
Even a dumbass CWI like myself knows you can put a 600# flange into a 150# line but you can't put a 150# flange into a 600# line !!!
If you have a 150# and 600# flange in the same system you would test to the lower pressure (the design engineer should already have ensured that the flanges nominated are rated over his/her design pressure)
On the current project I am on we have approximately 20,000 hydrotests to perform, if the design engineer says we test to xxxx psi/kpa I test to that whether he has added 300,600, or 900 # flanges into a 150# system, it is totally irrelevant.
It is his role to design it, mine to perform/supervise or witness the test (not to be pulling out a calculator to decide if it complies with the flange rating).
Regards,
Shane
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