45 degree reinforcement ring

[peipei]

Hallo guys,

I am a new fish here and also for the pipe stress analysis.

I am busy with a new project which contains lots of 45 degree reinforcement connections. The transport medium is HC Gas. We use Ple4win for the pipe analysis but it's impossible in the program to give a more than 5 degree tee connection.

there is also no equation in ASME B31.8. Is there a way to get the stress in those connections?

Regards
peipei

 

[C2it]

Pressure stress is dealt with in all B31 Codes by definition of the required reinforcement area.

I guess it's the stress intensification factor for a lateral tee that you are looking for. The only Code I know of that addresses this is the French Codeti, which takes the sif for a 90 degree connection and increases it by dividing it by {sin(angle)}^(3/2).

 

[peipei]

Hi,

thans for your information, i will try to figure out firstly how SIF works in Ple4win for tees, then i will try the french code.

 

[peipei]

another question,

for tee stuk, SIF has out-plane and in-plane, how are these two factors influence the stress?

For example,

SEOT=Sqr(SXIT^2+SFIT^2-SXIT*SFIT+3TZUT^2), just multiply the factor with the detail stress?

Regards
peipei

 

[Duwe6]

Are your branch connections too large for Laterl-O'Lets?? Integrally reinforced fittings are slightly over-reinforced and don't require further calculation.

 

[pennpiper]

Wow! so much missing information about your question. You asked for help but you only told us two things (45 degree reinforcement connections. The transport medium is HC Gas.)

What is the Operating Pressure?
What is the Operating Temperature?
Is this a Flare Heater?
Is this a sustained temperature or only an occasional excursion?
What is the Material?
What is the Header Size?
What is the Branch Size?
Where is the Anchor on the main Header relative to the Branch line?
What is the distance on the Branch lines before a lateral restraint?

You see, there is more to the question than you have shared with us.

 

[peipei]

hehe, sorry sorry, i am a bad questioner!

Yes, the configuration for the gas statio is really big. And we don't use fine element program.So i guess the calculation is quite concept in the program i use.

the operating pressure is 7 bar, operating temprature is different from mainleiding and branch leiding. The material is also specific according to the drawing. So i just pick one 45 degree tee as an example.

Run: 24'' ASTM A106 GR B SMLESS SCH.40
Branch: 8'' ASTM A106 GRB SMLESS SCH.40
Pressure: 7 bar
Temperature:
Run: -65/+38
Branch: -20/+50

By the way, how to combine SIF-in plane and SIF-out plane if only i have to input only one SIF?

 

[Duwe6]

Buy Weld-O'Lets for your 45° laterals. No calc's required, as their inherent reinforcement is greater than required at the bursting pressure of the pipe.

Second best method is to have oval repads made to fully reinforce the holes. The calculation on this is straightforward -- the area of the repad has to 'replace' the missing area of the pipe caused by the hole you cut.

 

[peipei]

hi, Duwe6,

Which standard has this regulation? Could you tell me?

 

[Duwe6]

It is from ASME B31.3 -- Process Piping, by way of ASME Sect VIII Div. 1. Either method will give you a fully reinforced opening, thus no further calcs are required.

I do not know of any 'middle ground' between these two methods, and a full FEA.

I'll bet that your pipe stress analysis program only looks at the external [bending] stresses and is missing the internal pressure stress. Pressure is the 'main event'. If your line splits open during hydro, nothing else matters. External stress can be dealt with using good supports and properly located pipe-guides and pipe-anchors.

 

[peipei]

Thanks Duwe6.

I am really not familiar with American codes, most of the cases we use Nederlandse Code. And the program is also according to NEN.

So it is the first time that i search the ASME B31.3....

Anyway i will take a look.

The program has a combination calculation with and without pressure.

 

[Duwe6]

I am reluctant to announce it too loudly in this multinational forum, but the USA codes, especially ASME seem to be more mature than the EU stuff. By mature, I mean that discrepancies and omissions have [mostly] been fixed, and that there are fewer areas that are not covered, do not have specified direction.

Just my opinion from where I stand. Please feel free to chime in with your observations.

 

[Duwe6]

Just occured to me that you probably not familiar with O-Lets. Here is a link to a catalog.

http://www.bonneyforge.com/resources/BC.pdf

 

[europipe]

Peipei, just curious, what Dutch code are you talking about?
I don´t know any.
There is a code EN13480, but Dutch?
You don´t have to do everything acc. codes,
there is something like mechanical calc.s too.
Greetings from a countryman.

 

[peipei]

Thanks Duwe6, we shift the codes according to client's design. Different clients also use different codes.

In this case, i will take a deep look at ASME, in previous case i only search the material specification.

To europipe,
we do have the EN13480(English) but i do not use too often.

The NL code is NEN serie, for example NEN-3650 & 3651.

 

[peipei]

best all, the problem is solved partly for the 45 degree Y-stuk. Here is the attachment of the study, unfortunately, it is in Dutch.

 

[waterpipe]

make sure that you've read ASME B31.8 para 841.23. there are many conditions that the deflection angle is limited considering the design hoop stress, deflection angle and pipe diameter. You are talking about 45 degree connection ...

 

[peipei]

hi, waterpipe,

I only calculate the stress according to the given configuration. It's our client who design the pipe.

and I am also worry about that the 45 degree connection will give me a lot of trouble.

 

[waterpipe]

Important: Check that you are using the same code as your client has used for his design. I'm thinking about how your client designed the connection without knowing the stresses (the most primary and important factor) and then asked you to check the stresses?

IMO, if you are trying to pick a code and then control the stresses, you should inform your client about your code and if your client's designed connection is (is not) as per this code requirements. It is not only about the physic of this connection but the consistency of the design and more important the liabilities.

 

[peipei]

hehe, cause it was designed 1971 and the pipe is already there. The code is ASME B31.8.

But when it was designed the temp is -20 degree but now they are going to lower it to -65 degree, that's why we have to control.